summaryrefslogtreecommitdiff
path: root/kernel/rcu/rcutorture.c
blob: ab4215266ebee7484227094273ee170c11583a08 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
// SPDX-License-Identifier: GPL-2.0+
/*
 * Read-Copy Update module-based torture test facility
 *
 * Copyright (C) IBM Corporation, 2005, 2006
 *
 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
 *	  Josh Triplett <josh@joshtriplett.org>
 *
 * See also:  Documentation/RCU/torture.rst
 */

#define pr_fmt(fmt) fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/rcupdate_wait.h>
#include <linux/interrupt.h>
#include <linux/sched/signal.h>
#include <uapi/linux/sched/types.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/trace_clock.h>
#include <asm/byteorder.h>
#include <linux/torture.h>
#include <linux/vmalloc.h>
#include <linux/sched/debug.h>
#include <linux/sched/sysctl.h>
#include <linux/oom.h>
#include <linux/tick.h>
#include <linux/rcupdate_trace.h>

#include "rcu.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");

/* Bits for ->extendables field, extendables param, and related definitions. */
#define RCUTORTURE_RDR_SHIFT	 8	/* Put SRCU index in upper bits. */
#define RCUTORTURE_RDR_MASK	 ((1 << RCUTORTURE_RDR_SHIFT) - 1)
#define RCUTORTURE_RDR_BH	 0x01	/* Extend readers by disabling bh. */
#define RCUTORTURE_RDR_IRQ	 0x02	/*  ... disabling interrupts. */
#define RCUTORTURE_RDR_PREEMPT	 0x04	/*  ... disabling preemption. */
#define RCUTORTURE_RDR_RBH	 0x08	/*  ... rcu_read_lock_bh(). */
#define RCUTORTURE_RDR_SCHED	 0x10	/*  ... rcu_read_lock_sched(). */
#define RCUTORTURE_RDR_RCU	 0x20	/*  ... entering another RCU reader. */
#define RCUTORTURE_RDR_NBITS	 6	/* Number of bits defined above. */
#define RCUTORTURE_MAX_EXTEND	 \
	(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
	 RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
#define RCUTORTURE_RDR_MAX_LOOPS 0x7	/* Maximum reader extensions. */
					/* Must be power of two minus one. */
#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)

torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
	      "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
torture_param(int, fqs_duration, 0,
	      "Duration of fqs bursts (us), 0 to disable");
torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
torture_param(int, fwd_progress_holdoff, 60,
	      "Time between forward-progress tests (s)");
torture_param(bool, fwd_progress_need_resched, 1,
	      "Hide cond_resched() behind need_resched()");
torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(bool, gp_normal, false,
	     "Use normal (non-expedited) GP wait primitives");
torture_param(bool, gp_poll, false, "Use polling GP wait primitives");
torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
torture_param(int, n_barrier_cbs, 0,
	     "# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, object_debug, 0,
	     "Enable debug-object double call_rcu() testing");
torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
torture_param(int, onoff_interval, 0,
	     "Time between CPU hotplugs (jiffies), 0=disable");
torture_param(int, nocbs_nthreads, 0, "Number of NOCB toggle threads, 0 to disable");
torture_param(int, nocbs_toggle, 1000, "Time between toggling nocb state (ms)");
torture_param(int, read_exit_delay, 13,
	      "Delay between read-then-exit episodes (s)");
torture_param(int, read_exit_burst, 16,
	      "# of read-then-exit bursts per episode, zero to disable");
torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
torture_param(int, stall_cpu_holdoff, 10,
	     "Time to wait before starting stall (s).");
torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
torture_param(int, stall_gp_kthread, 0,
	      "Grace-period kthread stall duration (s).");
torture_param(int, stat_interval, 60,
	     "Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
torture_param(int, test_boost_duration, 4,
	     "Duration of each boost test, seconds.");
torture_param(int, test_boost_interval, 7,
	     "Interval between boost tests, seconds.");
torture_param(bool, test_no_idle_hz, true,
	     "Test support for tickless idle CPUs");
torture_param(int, verbose, 1,
	     "Enable verbose debugging printk()s");

static char *torture_type = "rcu";
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");

static int nrealnocbers;
static int nrealreaders;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
static struct task_struct **nocb_tasks;
static struct task_struct *stats_task;
static struct task_struct *fqs_task;
static struct task_struct *boost_tasks[NR_CPUS];
static struct task_struct *stall_task;
static struct task_struct *fwd_prog_task;
static struct task_struct **barrier_cbs_tasks;
static struct task_struct *barrier_task;
static struct task_struct *read_exit_task;

#define RCU_TORTURE_PIPE_LEN 10

// Mailbox-like structure to check RCU global memory ordering.
struct rcu_torture_reader_check {
	unsigned long rtc_myloops;
	int rtc_chkrdr;
	unsigned long rtc_chkloops;
	int rtc_ready;
	struct rcu_torture_reader_check *rtc_assigner;
} ____cacheline_internodealigned_in_smp;

// Update-side data structure used to check RCU readers.
struct rcu_torture {
	struct rcu_head rtort_rcu;
	int rtort_pipe_count;
	struct list_head rtort_free;
	int rtort_mbtest;
	struct rcu_torture_reader_check *rtort_chkp;
};

static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture __rcu *rcu_torture_current;
static unsigned long rcu_torture_current_version;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
static struct rcu_torture_reader_check *rcu_torture_reader_mbchk;
static atomic_t n_rcu_torture_alloc;
static atomic_t n_rcu_torture_alloc_fail;
static atomic_t n_rcu_torture_free;
static atomic_t n_rcu_torture_mberror;
static atomic_t n_rcu_torture_mbchk_fail;
static atomic_t n_rcu_torture_mbchk_tries;
static atomic_t n_rcu_torture_error;
static long n_rcu_torture_barrier_error;
static long n_rcu_torture_boost_ktrerror;
static long n_rcu_torture_boost_rterror;
static long n_rcu_torture_boost_failure;
static long n_rcu_torture_boosts;
static atomic_long_t n_rcu_torture_timers;
static long n_barrier_attempts;
static long n_barrier_successes; /* did rcu_barrier test succeed? */
static unsigned long n_read_exits;
static struct list_head rcu_torture_removed;
static unsigned long shutdown_jiffies;
static unsigned long start_gp_seq;
static atomic_long_t n_nocb_offload;
static atomic_long_t n_nocb_deoffload;

static int rcu_torture_writer_state;
#define RTWS_FIXED_DELAY	0
#define RTWS_DELAY		1
#define RTWS_REPLACE		2
#define RTWS_DEF_FREE		3
#define RTWS_EXP_SYNC		4
#define RTWS_COND_GET		5
#define RTWS_COND_SYNC		6
#define RTWS_POLL_GET		7
#define RTWS_POLL_WAIT		8
#define RTWS_SYNC		9
#define RTWS_STUTTER		10
#define RTWS_STOPPING		11
static const char * const rcu_torture_writer_state_names[] = {
	"RTWS_FIXED_DELAY",
	"RTWS_DELAY",
	"RTWS_REPLACE",
	"RTWS_DEF_FREE",
	"RTWS_EXP_SYNC",
	"RTWS_COND_GET",
	"RTWS_COND_SYNC",
	"RTWS_POLL_GET",
	"RTWS_POLL_WAIT",
	"RTWS_SYNC",
	"RTWS_STUTTER",
	"RTWS_STOPPING",
};

/* Record reader segment types and duration for first failing read. */
struct rt_read_seg {
	int rt_readstate;
	unsigned long rt_delay_jiffies;
	unsigned long rt_delay_ms;
	unsigned long rt_delay_us;
	bool rt_preempted;
};
static int err_segs_recorded;
static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
static int rt_read_nsegs;

static const char *rcu_torture_writer_state_getname(void)
{
	unsigned int i = READ_ONCE(rcu_torture_writer_state);

	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
		return "???";
	return rcu_torture_writer_state_names[i];
}

#ifdef CONFIG_RCU_TRACE
static u64 notrace rcu_trace_clock_local(void)
{
	u64 ts = trace_clock_local();

	(void)do_div(ts, NSEC_PER_USEC);
	return ts;
}
#else /* #ifdef CONFIG_RCU_TRACE */
static u64 notrace rcu_trace_clock_local(void)
{
	return 0ULL;
}
#endif /* #else #ifdef CONFIG_RCU_TRACE */

/*
 * Stop aggressive CPU-hog tests a bit before the end of the test in order
 * to avoid interfering with test shutdown.
 */
static bool shutdown_time_arrived(void)
{
	return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
}

static unsigned long boost_starttime;	/* jiffies of next boost test start. */
static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
					/*  and boost task create/destroy. */
static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
static bool barrier_phase;		/* Test phase. */
static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);

static bool rcu_fwd_cb_nodelay;		/* Short rcu_torture_delay() delays. */

/*
 * Allocate an element from the rcu_tortures pool.
 */
static struct rcu_torture *
rcu_torture_alloc(void)
{
	struct list_head *p;

	spin_lock_bh(&rcu_torture_lock);
	if (list_empty(&rcu_torture_freelist)) {
		atomic_inc(&n_rcu_torture_alloc_fail);
		spin_unlock_bh(&rcu_torture_lock);
		return NULL;
	}
	atomic_inc(&n_rcu_torture_alloc);
	p = rcu_torture_freelist.next;
	list_del_init(p);
	spin_unlock_bh(&rcu_torture_lock);
	return container_of(p, struct rcu_torture, rtort_free);
}

/*
 * Free an element to the rcu_tortures pool.
 */
static void
rcu_torture_free(struct rcu_torture *p)
{
	atomic_inc(&n_rcu_torture_free);
	spin_lock_bh(&rcu_torture_lock);
	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
	spin_unlock_bh(&rcu_torture_lock);
}

/*
 * Operations vector for selecting different types of tests.
 */

struct rcu_torture_ops {
	int ttype;
	void (*init)(void);
	void (*cleanup)(void);
	int (*readlock)(void);
	void (*read_delay)(struct torture_random_state *rrsp,
			   struct rt_read_seg *rtrsp);
	void (*readunlock)(int idx);
	int (*readlock_held)(void);
	unsigned long (*get_gp_seq)(void);
	unsigned long (*gp_diff)(unsigned long new, unsigned long old);
	void (*deferred_free)(struct rcu_torture *p);
	void (*sync)(void);
	void (*exp_sync)(void);
	unsigned long (*get_gp_state)(void);
	unsigned long (*start_gp_poll)(void);
	bool (*poll_gp_state)(unsigned long oldstate);
	void (*cond_sync)(unsigned long oldstate);
	call_rcu_func_t call;
	void (*cb_barrier)(void);
	void (*fqs)(void);
	void (*stats)(void);
	void (*gp_kthread_dbg)(void);
	bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
	int (*stall_dur)(void);
	int irq_capable;
	int can_boost;
	int extendables;
	int slow_gps;
	const char *name;
};

static struct rcu_torture_ops *cur_ops;

/*
 * Definitions for rcu torture testing.
 */

static int torture_readlock_not_held(void)
{
	return rcu_read_lock_bh_held() || rcu_read_lock_sched_held();
}

static int rcu_torture_read_lock(void) __acquires(RCU)
{
	rcu_read_lock();
	return 0;
}

static void
rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
	unsigned long started;
	unsigned long completed;
	const unsigned long shortdelay_us = 200;
	unsigned long longdelay_ms = 300;
	unsigned long long ts;

	/* We want a short delay sometimes to make a reader delay the grace
	 * period, and we want a long delay occasionally to trigger
	 * force_quiescent_state. */

	if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
	    !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
		started = cur_ops->get_gp_seq();
		ts = rcu_trace_clock_local();
		if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
			longdelay_ms = 5; /* Avoid triggering BH limits. */
		mdelay(longdelay_ms);
		rtrsp->rt_delay_ms = longdelay_ms;
		completed = cur_ops->get_gp_seq();
		do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
					  started, completed);
	}
	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
		udelay(shortdelay_us);
		rtrsp->rt_delay_us = shortdelay_us;
	}
	if (!preempt_count() &&
	    !(torture_random(rrsp) % (nrealreaders * 500))) {
		torture_preempt_schedule();  /* QS only if preemptible. */
		rtrsp->rt_preempted = true;
	}
}

static void rcu_torture_read_unlock(int idx) __releases(RCU)
{
	rcu_read_unlock();
}

/*
 * Update callback in the pipe.  This should be invoked after a grace period.
 */
static bool
rcu_torture_pipe_update_one(struct rcu_torture *rp)
{
	int i;
	struct rcu_torture_reader_check *rtrcp = READ_ONCE(rp->rtort_chkp);

	if (rtrcp) {
		WRITE_ONCE(rp->rtort_chkp, NULL);
		smp_store_release(&rtrcp->rtc_ready, 1); // Pair with smp_load_acquire().
	}
	i = READ_ONCE(rp->rtort_pipe_count);
	if (i > RCU_TORTURE_PIPE_LEN)
		i = RCU_TORTURE_PIPE_LEN;
	atomic_inc(&rcu_torture_wcount[i]);
	WRITE_ONCE(rp->rtort_pipe_count, i + 1);
	if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
		rp->rtort_mbtest = 0;
		return true;
	}
	return false;
}

/*
 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 * primitives.
 */
static void
rcu_torture_pipe_update(struct rcu_torture *old_rp)
{
	struct rcu_torture *rp;
	struct rcu_torture *rp1;

	if (old_rp)
		list_add(&old_rp->rtort_free, &rcu_torture_removed);
	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
		if (rcu_torture_pipe_update_one(rp)) {
			list_del(&rp->rtort_free);
			rcu_torture_free(rp);
		}
	}
}

static void
rcu_torture_cb(struct rcu_head *p)
{
	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);

	if (torture_must_stop_irq()) {
		/* Test is ending, just drop callbacks on the floor. */
		/* The next initialization will pick up the pieces. */
		return;
	}
	if (rcu_torture_pipe_update_one(rp))
		rcu_torture_free(rp);
	else
		cur_ops->deferred_free(rp);
}

static unsigned long rcu_no_completed(void)
{
	return 0;
}

static void rcu_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu(&p->rtort_rcu, rcu_torture_cb);
}

static void rcu_sync_torture_init(void)
{
	INIT_LIST_HEAD(&rcu_torture_removed);
}

static struct rcu_torture_ops rcu_ops = {
	.ttype			= RCU_FLAVOR,
	.init			= rcu_sync_torture_init,
	.readlock		= rcu_torture_read_lock,
	.read_delay		= rcu_read_delay,
	.readunlock		= rcu_torture_read_unlock,
	.readlock_held		= torture_readlock_not_held,
	.get_gp_seq		= rcu_get_gp_seq,
	.gp_diff		= rcu_seq_diff,
	.deferred_free		= rcu_torture_deferred_free,
	.sync			= synchronize_rcu,
	.exp_sync		= synchronize_rcu_expedited,
	.get_gp_state		= get_state_synchronize_rcu,
	.start_gp_poll		= start_poll_synchronize_rcu,
	.poll_gp_state		= poll_state_synchronize_rcu,
	.cond_sync		= cond_synchronize_rcu,
	.call			= call_rcu,
	.cb_barrier		= rcu_barrier,
	.fqs			= rcu_force_quiescent_state,
	.stats			= NULL,
	.gp_kthread_dbg		= show_rcu_gp_kthreads,
	.check_boost_failed	= rcu_check_boost_fail,
	.stall_dur		= rcu_jiffies_till_stall_check,
	.irq_capable		= 1,
	.can_boost		= IS_ENABLED(CONFIG_RCU_BOOST),
	.extendables		= RCUTORTURE_MAX_EXTEND,
	.name			= "rcu"
};

/*
 * Don't even think about trying any of these in real life!!!
 * The names includes "busted", and they really means it!
 * The only purpose of these functions is to provide a buggy RCU
 * implementation to make sure that rcutorture correctly emits
 * buggy-RCU error messages.
 */
static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
{
	/* This is a deliberate bug for testing purposes only! */
	rcu_torture_cb(&p->rtort_rcu);
}

static void synchronize_rcu_busted(void)
{
	/* This is a deliberate bug for testing purposes only! */
}

static void
call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
{
	/* This is a deliberate bug for testing purposes only! */
	func(head);
}

static struct rcu_torture_ops rcu_busted_ops = {
	.ttype		= INVALID_RCU_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= rcu_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= rcu_torture_read_unlock,
	.readlock_held	= torture_readlock_not_held,
	.get_gp_seq	= rcu_no_completed,
	.deferred_free	= rcu_busted_torture_deferred_free,
	.sync		= synchronize_rcu_busted,
	.exp_sync	= synchronize_rcu_busted,
	.call		= call_rcu_busted,
	.cb_barrier	= NULL,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "busted"
};

/*
 * Definitions for srcu torture testing.
 */

DEFINE_STATIC_SRCU(srcu_ctl);
static struct srcu_struct srcu_ctld;
static struct srcu_struct *srcu_ctlp = &srcu_ctl;

static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
{
	return srcu_read_lock(srcu_ctlp);
}

static void
srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
	long delay;
	const long uspertick = 1000000 / HZ;
	const long longdelay = 10;

	/* We want there to be long-running readers, but not all the time. */

	delay = torture_random(rrsp) %
		(nrealreaders * 2 * longdelay * uspertick);
	if (!delay && in_task()) {
		schedule_timeout_interruptible(longdelay);
		rtrsp->rt_delay_jiffies = longdelay;
	} else {
		rcu_read_delay(rrsp, rtrsp);
	}
}

static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
{
	srcu_read_unlock(srcu_ctlp, idx);
}

static int torture_srcu_read_lock_held(void)
{
	return srcu_read_lock_held(srcu_ctlp);
}

static unsigned long srcu_torture_completed(void)
{
	return srcu_batches_completed(srcu_ctlp);
}

static void srcu_torture_deferred_free(struct rcu_torture *rp)
{
	call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
}

static void srcu_torture_synchronize(void)
{
	synchronize_srcu(srcu_ctlp);
}

static unsigned long srcu_torture_get_gp_state(void)
{
	return get_state_synchronize_srcu(srcu_ctlp);
}

static unsigned long srcu_torture_start_gp_poll(void)
{
	return start_poll_synchronize_srcu(srcu_ctlp);
}

static bool srcu_torture_poll_gp_state(unsigned long oldstate)
{
	return poll_state_synchronize_srcu(srcu_ctlp, oldstate);
}

static void srcu_torture_call(struct rcu_head *head,
			      rcu_callback_t func)
{
	call_srcu(srcu_ctlp, head, func);
}

static void srcu_torture_barrier(void)
{
	srcu_barrier(srcu_ctlp);
}

static void srcu_torture_stats(void)
{
	srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
}

static void srcu_torture_synchronize_expedited(void)
{
	synchronize_srcu_expedited(srcu_ctlp);
}

static struct rcu_torture_ops srcu_ops = {
	.ttype		= SRCU_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= srcu_torture_read_lock,
	.read_delay	= srcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
	.readlock_held	= torture_srcu_read_lock_held,
	.get_gp_seq	= srcu_torture_completed,
	.deferred_free	= srcu_torture_deferred_free,
	.sync		= srcu_torture_synchronize,
	.exp_sync	= srcu_torture_synchronize_expedited,
	.get_gp_state	= srcu_torture_get_gp_state,
	.start_gp_poll	= srcu_torture_start_gp_poll,
	.poll_gp_state	= srcu_torture_poll_gp_state,
	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
	.stats		= srcu_torture_stats,
	.irq_capable	= 1,
	.name		= "srcu"
};

static void srcu_torture_init(void)
{
	rcu_sync_torture_init();
	WARN_ON(init_srcu_struct(&srcu_ctld));
	srcu_ctlp = &srcu_ctld;
}

static void srcu_torture_cleanup(void)
{
	cleanup_srcu_struct(&srcu_ctld);
	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
}

/* As above, but dynamically allocated. */
static struct rcu_torture_ops srcud_ops = {
	.ttype		= SRCU_FLAVOR,
	.init		= srcu_torture_init,
	.cleanup	= srcu_torture_cleanup,
	.readlock	= srcu_torture_read_lock,
	.read_delay	= srcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
	.readlock_held	= torture_srcu_read_lock_held,
	.get_gp_seq	= srcu_torture_completed,
	.deferred_free	= srcu_torture_deferred_free,
	.sync		= srcu_torture_synchronize,
	.exp_sync	= srcu_torture_synchronize_expedited,
	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
	.stats		= srcu_torture_stats,
	.irq_capable	= 1,
	.name		= "srcud"
};

/* As above, but broken due to inappropriate reader extension. */
static struct rcu_torture_ops busted_srcud_ops = {
	.ttype		= SRCU_FLAVOR,
	.init		= srcu_torture_init,
	.cleanup	= srcu_torture_cleanup,
	.readlock	= srcu_torture_read_lock,
	.read_delay	= rcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
	.readlock_held	= torture_srcu_read_lock_held,
	.get_gp_seq	= srcu_torture_completed,
	.deferred_free	= srcu_torture_deferred_free,
	.sync		= srcu_torture_synchronize,
	.exp_sync	= srcu_torture_synchronize_expedited,
	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
	.stats		= srcu_torture_stats,
	.irq_capable	= 1,
	.extendables	= RCUTORTURE_MAX_EXTEND,
	.name		= "busted_srcud"
};

/*
 * Definitions for RCU-tasks torture testing.
 */

static int tasks_torture_read_lock(void)
{
	return 0;
}

static void tasks_torture_read_unlock(int idx)
{
}

static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
}

static void synchronize_rcu_mult_test(void)
{
	synchronize_rcu_mult(call_rcu_tasks, call_rcu);
}

static struct rcu_torture_ops tasks_ops = {
	.ttype		= RCU_TASKS_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= tasks_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= tasks_torture_read_unlock,
	.get_gp_seq	= rcu_no_completed,
	.deferred_free	= rcu_tasks_torture_deferred_free,
	.sync		= synchronize_rcu_tasks,
	.exp_sync	= synchronize_rcu_mult_test,
	.call		= call_rcu_tasks,
	.cb_barrier	= rcu_barrier_tasks,
	.gp_kthread_dbg	= show_rcu_tasks_classic_gp_kthread,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.slow_gps	= 1,
	.name		= "tasks"
};

/*
 * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 * This implementation does not necessarily work well with CPU hotplug.
 */

static void synchronize_rcu_trivial(void)
{
	int cpu;

	for_each_online_cpu(cpu) {
		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
	}
}

static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
{
	preempt_disable();
	return 0;
}

static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
{
	preempt_enable();
}

static struct rcu_torture_ops trivial_ops = {
	.ttype		= RCU_TRIVIAL_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= rcu_torture_read_lock_trivial,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= rcu_torture_read_unlock_trivial,
	.readlock_held	= torture_readlock_not_held,
	.get_gp_seq	= rcu_no_completed,
	.sync		= synchronize_rcu_trivial,
	.exp_sync	= synchronize_rcu_trivial,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "trivial"
};

/*
 * Definitions for rude RCU-tasks torture testing.
 */

static void rcu_tasks_rude_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu_tasks_rude(&p->rtort_rcu, rcu_torture_cb);
}

static struct rcu_torture_ops tasks_rude_ops = {
	.ttype		= RCU_TASKS_RUDE_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= rcu_torture_read_lock_trivial,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= rcu_torture_read_unlock_trivial,
	.get_gp_seq	= rcu_no_completed,
	.deferred_free	= rcu_tasks_rude_torture_deferred_free,
	.sync		= synchronize_rcu_tasks_rude,
	.exp_sync	= synchronize_rcu_tasks_rude,
	.call		= call_rcu_tasks_rude,
	.cb_barrier	= rcu_barrier_tasks_rude,
	.gp_kthread_dbg	= show_rcu_tasks_rude_gp_kthread,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "tasks-rude"
};

/*
 * Definitions for tracing RCU-tasks torture testing.
 */

static int tasks_tracing_torture_read_lock(void)
{
	rcu_read_lock_trace();
	return 0;
}

static void tasks_tracing_torture_read_unlock(int idx)
{
	rcu_read_unlock_trace();
}

static void rcu_tasks_tracing_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu_tasks_trace(&p->rtort_rcu, rcu_torture_cb);
}

static struct rcu_torture_ops tasks_tracing_ops = {
	.ttype		= RCU_TASKS_TRACING_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= tasks_tracing_torture_read_lock,
	.read_delay	= srcu_read_delay,  /* just reuse srcu's version. */
	.readunlock	= tasks_tracing_torture_read_unlock,
	.readlock_held	= rcu_read_lock_trace_held,
	.get_gp_seq	= rcu_no_completed,
	.deferred_free	= rcu_tasks_tracing_torture_deferred_free,
	.sync		= synchronize_rcu_tasks_trace,
	.exp_sync	= synchronize_rcu_tasks_trace,
	.call		= call_rcu_tasks_trace,
	.cb_barrier	= rcu_barrier_tasks_trace,
	.gp_kthread_dbg	= show_rcu_tasks_trace_gp_kthread,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.slow_gps	= 1,
	.name		= "tasks-tracing"
};

static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
{
	if (!cur_ops->gp_diff)
		return new - old;
	return cur_ops->gp_diff(new, old);
}

/*
 * RCU torture priority-boost testing.  Runs one real-time thread per
 * CPU for moderate bursts, repeatedly starting grace periods and waiting
 * for them to complete.  If a given grace period takes too long, we assume
 * that priority inversion has occurred.
 */

static int old_rt_runtime = -1;

static void rcu_torture_disable_rt_throttle(void)
{
	/*
	 * Disable RT throttling so that rcutorture's boost threads don't get
	 * throttled. Only possible if rcutorture is built-in otherwise the
	 * user should manually do this by setting the sched_rt_period_us and
	 * sched_rt_runtime sysctls.
	 */
	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
		return;

	old_rt_runtime = sysctl_sched_rt_runtime;
	sysctl_sched_rt_runtime = -1;
}

static void rcu_torture_enable_rt_throttle(void)
{
	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
		return;

	sysctl_sched_rt_runtime = old_rt_runtime;
	old_rt_runtime = -1;
}

static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long *start)
{
	int cpu;
	static int dbg_done;
	unsigned long end = jiffies;
	bool gp_done;
	unsigned long j;
	static unsigned long last_persist;
	unsigned long lp;
	unsigned long mininterval = test_boost_duration * HZ - HZ / 2;

	if (end - *start > mininterval) {
		// Recheck after checking time to avoid false positives.
		smp_mb(); // Time check before grace-period check.
		if (cur_ops->poll_gp_state(gp_state))
			return false; // passed, though perhaps just barely
		if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, &cpu)) {
			// At most one persisted message per boost test.
			j = jiffies;
			lp = READ_ONCE(last_persist);
			if (time_after(j, lp + mininterval) && cmpxchg(&last_persist, lp, j) == lp)
				pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
			return false; // passed on a technicality
		}
		VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
		n_rcu_torture_boost_failure++;
		if (!xchg(&dbg_done, 1) && cur_ops->gp_kthread_dbg) {
			pr_info("Boost inversion thread ->rt_priority %u gp_state %lu jiffies %lu\n",
				current->rt_priority, gp_state, end - *start);
			cur_ops->gp_kthread_dbg();
			// Recheck after print to flag grace period ending during splat.
			gp_done = cur_ops->poll_gp_state(gp_state);
			pr_info("Boost inversion: GP %lu %s.\n", gp_state,
				gp_done ? "ended already" : "still pending");

		}

		return true; // failed
	} else if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, NULL)) {
		*start = jiffies;
	}

	return false; // passed
}

static int rcu_torture_boost(void *arg)
{
	unsigned long endtime;
	unsigned long gp_state;
	unsigned long gp_state_time;
	unsigned long oldstarttime;

	VERBOSE_TOROUT_STRING("rcu_torture_boost started");

	/* Set real-time priority. */
	sched_set_fifo_low(current);

	/* Each pass through the following loop does one boost-test cycle. */
	do {
		bool failed = false; // Test failed already in this test interval
		bool gp_initiated = false;

		if (kthread_should_stop())
			goto checkwait;

		/* Wait for the next test interval. */
		oldstarttime = boost_starttime;
		while (time_before(jiffies, oldstarttime)) {
			schedule_timeout_interruptible(oldstarttime - jiffies);
			if (stutter_wait("rcu_torture_boost"))
				sched_set_fifo_low(current);
			if (torture_must_stop())
				goto checkwait;
		}

		// Do one boost-test interval.
		endtime = oldstarttime + test_boost_duration * HZ;
		while (time_before(jiffies, endtime)) {
			// Has current GP gone too long?
			if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
				failed = rcu_torture_boost_failed(gp_state, &gp_state_time);
			// If we don't have a grace period in flight, start one.
			if (!gp_initiated || cur_ops->poll_gp_state(gp_state)) {
				gp_state = cur_ops->start_gp_poll();
				gp_initiated = true;
				gp_state_time = jiffies;
			}
			if (stutter_wait("rcu_torture_boost")) {
				sched_set_fifo_low(current);
				// If the grace period already ended,
				// we don't know when that happened, so
				// start over.
				if (cur_ops->poll_gp_state(gp_state))
					gp_initiated = false;
			}
			if (torture_must_stop())
				goto checkwait;
		}

		// In case the grace period extended beyond the end of the loop.
		if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
			rcu_torture_boost_failed(gp_state, &gp_state_time);

		/*
		 * Set the start time of the next test interval.
		 * Yes, this is vulnerable to long delays, but such
		 * delays simply cause a false negative for the next
		 * interval.  Besides, we are running at RT priority,
		 * so delays should be relatively rare.
		 */
		while (oldstarttime == boost_starttime && !kthread_should_stop()) {
			if (mutex_trylock(&boost_mutex)) {
				if (oldstarttime == boost_starttime) {
					boost_starttime = jiffies + test_boost_interval * HZ;
					n_rcu_torture_boosts++;
				}
				mutex_unlock(&boost_mutex);
				break;
			}
			schedule_timeout_uninterruptible(1);
		}

		/* Go do the stutter. */
checkwait:	if (stutter_wait("rcu_torture_boost"))
			sched_set_fifo_low(current);
	} while (!torture_must_stop());

	/* Clean up and exit. */
	while (!kthread_should_stop()) {
		torture_shutdown_absorb("rcu_torture_boost");
		schedule_timeout_uninterruptible(1);
	}
	torture_kthread_stopping("rcu_torture_boost");
	return 0;
}

/*
 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 * bursts of calls to force_quiescent_state(), increasing the probability
 * of occurrence of some important types of race conditions.
 */
static int
rcu_torture_fqs(void *arg)
{
	unsigned long fqs_resume_time;
	int fqs_burst_remaining;
	int oldnice = task_nice(current);

	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
	do {
		fqs_resume_time = jiffies + fqs_stutter * HZ;
		while (time_before(jiffies, fqs_resume_time) &&
		       !kthread_should_stop()) {
			schedule_timeout_interruptible(1);
		}
		fqs_burst_remaining = fqs_duration;
		while (fqs_burst_remaining > 0 &&
		       !kthread_should_stop()) {
			cur_ops->fqs();
			udelay(fqs_holdoff);
			fqs_burst_remaining -= fqs_holdoff;
		}
		if (stutter_wait("rcu_torture_fqs"))
			sched_set_normal(current, oldnice);
	} while (!torture_must_stop());
	torture_kthread_stopping("rcu_torture_fqs");
	return 0;
}

// Used by writers to randomly choose from the available grace-period
// primitives.  The only purpose of the initialization is to size the array.
static int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC, RTWS_COND_GET, RTWS_POLL_GET, RTWS_SYNC };
static int nsynctypes;

/*
 * Determine which grace-period primitives are available.
 */
static void rcu_torture_write_types(void)
{
	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
	bool gp_poll1 = gp_poll, gp_sync1 = gp_sync;

	/* Initialize synctype[] array.  If none set, take default. */
	if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_poll1 && !gp_sync1)
		gp_cond1 = gp_exp1 = gp_normal1 = gp_poll1 = gp_sync1 = true;
	if (gp_cond1 && cur_ops->get_gp_state && cur_ops->cond_sync) {
		synctype[nsynctypes++] = RTWS_COND_GET;
		pr_info("%s: Testing conditional GPs.\n", __func__);
	} else if (gp_cond && (!cur_ops->get_gp_state || !cur_ops->cond_sync)) {
		pr_alert("%s: gp_cond without primitives.\n", __func__);
	}
	if (gp_exp1 && cur_ops->exp_sync) {
		synctype[nsynctypes++] = RTWS_EXP_SYNC;
		pr_info("%s: Testing expedited GPs.\n", __func__);
	} else if (gp_exp && !cur_ops->exp_sync) {
		pr_alert("%s: gp_exp without primitives.\n", __func__);
	}
	if (gp_normal1 && cur_ops->deferred_free) {
		synctype[nsynctypes++] = RTWS_DEF_FREE;
		pr_info("%s: Testing asynchronous GPs.\n", __func__);
	} else if (gp_normal && !cur_ops->deferred_free) {
		pr_alert("%s: gp_normal without primitives.\n", __func__);
	}
	if (gp_poll1 && cur_ops->start_gp_poll && cur_ops->poll_gp_state) {
		synctype[nsynctypes++] = RTWS_POLL_GET;
		pr_info("%s: Testing polling GPs.\n", __func__);
	} else if (gp_poll && (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)) {
		pr_alert("%s: gp_poll without primitives.\n", __func__);
	}
	if (gp_sync1 && cur_ops->sync) {
		synctype[nsynctypes++] = RTWS_SYNC;
		pr_info("%s: Testing normal GPs.\n", __func__);
	} else if (gp_sync && !cur_ops->sync) {
		pr_alert("%s: gp_sync without primitives.\n", __func__);
	}
}

/*
 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 * for that pointed to by rcu_torture_current, freeing the old structure
 * after a series of grace periods (the "pipeline").
 */
static int
rcu_torture_writer(void *arg)
{
	bool boot_ended;
	bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
	unsigned long cookie;
	int expediting = 0;
	unsigned long gp_snap;
	int i;
	int idx;
	int oldnice = task_nice(current);
	struct rcu_torture *rp;
	struct rcu_torture *old_rp;
	static DEFINE_TORTURE_RANDOM(rand);
	bool stutter_waited;

	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
	if (!can_expedite)
		pr_alert("%s" TORTURE_FLAG
			 " GP expediting controlled from boot/sysfs for %s.\n",
			 torture_type, cur_ops->name);
	if (WARN_ONCE(nsynctypes == 0,
		      "rcu_torture_writer: No update-side primitives.\n")) {
		/*
		 * No updates primitives, so don't try updating.
		 * The resulting test won't be testing much, hence the
		 * above WARN_ONCE().
		 */
		rcu_torture_writer_state = RTWS_STOPPING;
		torture_kthread_stopping("rcu_torture_writer");
	}

	do {
		rcu_torture_writer_state = RTWS_FIXED_DELAY;
		torture_hrtimeout_us(500, 1000, &rand);
		rp = rcu_torture_alloc();
		if (rp == NULL)
			continue;
		rp->rtort_pipe_count = 0;
		rcu_torture_writer_state = RTWS_DELAY;
		udelay(torture_random(&rand) & 0x3ff);
		rcu_torture_writer_state = RTWS_REPLACE;
		old_rp = rcu_dereference_check(rcu_torture_current,
					       current == writer_task);
		rp->rtort_mbtest = 1;
		rcu_assign_pointer(rcu_torture_current, rp);
		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
		if (old_rp) {
			i = old_rp->rtort_pipe_count;
			if (i > RCU_TORTURE_PIPE_LEN)
				i = RCU_TORTURE_PIPE_LEN;
			atomic_inc(&rcu_torture_wcount[i]);
			WRITE_ONCE(old_rp->rtort_pipe_count,
				   old_rp->rtort_pipe_count + 1);
			if (cur_ops->get_gp_state && cur_ops->poll_gp_state) {
				idx = cur_ops->readlock();
				cookie = cur_ops->get_gp_state();
				WARN_ONCE(rcu_torture_writer_state != RTWS_DEF_FREE &&
					  cur_ops->poll_gp_state(cookie),
					  "%s: Cookie check 1 failed %s(%d) %lu->%lu\n",
					  __func__,
					  rcu_torture_writer_state_getname(),
					  rcu_torture_writer_state,
					  cookie, cur_ops->get_gp_state());
				cur_ops->readunlock(idx);
			}
			switch (synctype[torture_random(&rand) % nsynctypes]) {
			case RTWS_DEF_FREE:
				rcu_torture_writer_state = RTWS_DEF_FREE;
				cur_ops->deferred_free(old_rp);
				break;
			case RTWS_EXP_SYNC:
				rcu_torture_writer_state = RTWS_EXP_SYNC;
				cur_ops->exp_sync();
				rcu_torture_pipe_update(old_rp);
				break;
			case RTWS_COND_GET:
				rcu_torture_writer_state = RTWS_COND_GET;
				gp_snap = cur_ops->get_gp_state();
				torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
				rcu_torture_writer_state = RTWS_COND_SYNC;
				cur_ops->cond_sync(gp_snap);
				rcu_torture_pipe_update(old_rp);
				break;
			case RTWS_POLL_GET:
				rcu_torture_writer_state = RTWS_POLL_GET;
				gp_snap = cur_ops->start_gp_poll();
				rcu_torture_writer_state = RTWS_POLL_WAIT;
				while (!cur_ops->poll_gp_state(gp_snap))
					torture_hrtimeout_jiffies(torture_random(&rand) % 16,
								  &rand);
				rcu_torture_pipe_update(old_rp);
				break;
			case RTWS_SYNC:
				rcu_torture_writer_state = RTWS_SYNC;
				cur_ops->sync();
				rcu_torture_pipe_update(old_rp);
				break;
			default:
				WARN_ON_ONCE(1);
				break;
			}
		}
		WRITE_ONCE(rcu_torture_current_version,
			   rcu_torture_current_version + 1);
		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
		if (can_expedite &&
		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
			if (expediting >= 0)
				rcu_expedite_gp();
			else
				rcu_unexpedite_gp();
			if (++expediting > 3)
				expediting = -expediting;
		} else if (!can_expedite) { /* Disabled during boot, recheck. */
			can_expedite = !rcu_gp_is_expedited() &&
				       !rcu_gp_is_normal();
		}
		rcu_torture_writer_state = RTWS_STUTTER;
		boot_ended = rcu_inkernel_boot_has_ended();
		stutter_waited = stutter_wait("rcu_torture_writer");
		if (stutter_waited &&
		    !READ_ONCE(rcu_fwd_cb_nodelay) &&
		    !cur_ops->slow_gps &&
		    !torture_must_stop() &&
		    boot_ended)
			for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
				if (list_empty(&rcu_tortures[i].rtort_free) &&
				    rcu_access_pointer(rcu_torture_current) !=
				    &rcu_tortures[i]) {
					rcu_ftrace_dump(DUMP_ALL);
					WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
				}
		if (stutter_waited)
			sched_set_normal(current, oldnice);
	} while (!torture_must_stop());
	rcu_torture_current = NULL;  // Let stats task know that we are done.
	/* Reset expediting back to unexpedited. */
	if (expediting > 0)
		expediting = -expediting;
	while (can_expedite && expediting++ < 0)
		rcu_unexpedite_gp();
	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
	if (!can_expedite)
		pr_alert("%s" TORTURE_FLAG
			 " Dynamic grace-period expediting was disabled.\n",
			 torture_type);
	rcu_torture_writer_state = RTWS_STOPPING;
	torture_kthread_stopping("rcu_torture_writer");
	return 0;
}

/*
 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 * delay between calls.
 */
static int
rcu_torture_fakewriter(void *arg)
{
	unsigned long gp_snap;
	DEFINE_TORTURE_RANDOM(rand);

	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
	set_user_nice(current, MAX_NICE);

	do {
		torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
		if (cur_ops->cb_barrier != NULL &&
		    torture_random(&rand) % (nfakewriters * 8) == 0) {
			cur_ops->cb_barrier();
		} else {
			switch (synctype[torture_random(&rand) % nsynctypes]) {
			case RTWS_DEF_FREE:
				break;
			case RTWS_EXP_SYNC:
				cur_ops->exp_sync();
				break;
			case RTWS_COND_GET:
				gp_snap = cur_ops->get_gp_state();
				torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
				cur_ops->cond_sync(gp_snap);
				break;
			case RTWS_POLL_GET:
				gp_snap = cur_ops->start_gp_poll();
				while (!cur_ops->poll_gp_state(gp_snap)) {
					torture_hrtimeout_jiffies(torture_random(&rand) % 16,
								  &rand);
				}
				break;
			case RTWS_SYNC:
				cur_ops->sync();
				break;
			default:
				WARN_ON_ONCE(1);
				break;
			}
		}
		stutter_wait("rcu_torture_fakewriter");
	} while (!torture_must_stop());

	torture_kthread_stopping("rcu_torture_fakewriter");
	return 0;
}

static void rcu_torture_timer_cb(struct rcu_head *rhp)
{
	kfree(rhp);
}

// Set up and carry out testing of RCU's global memory ordering
static void rcu_torture_reader_do_mbchk(long myid, struct rcu_torture *rtp,
					struct torture_random_state *trsp)
{
	unsigned long loops;
	int noc = torture_num_online_cpus();
	int rdrchked;
	int rdrchker;
	struct rcu_torture_reader_check *rtrcp; // Me.
	struct rcu_torture_reader_check *rtrcp_assigner; // Assigned us to do checking.
	struct rcu_torture_reader_check *rtrcp_chked; // Reader being checked.
	struct rcu_torture_reader_check *rtrcp_chker; // Reader doing checking when not me.

	if (myid < 0)
		return; // Don't try this from timer handlers.

	// Increment my counter.
	rtrcp = &rcu_torture_reader_mbchk[myid];
	WRITE_ONCE(rtrcp->rtc_myloops, rtrcp->rtc_myloops + 1);

	// Attempt to assign someone else some checking work.
	rdrchked = torture_random(trsp) % nrealreaders;
	rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
	rdrchker = torture_random(trsp) % nrealreaders;
	rtrcp_chker = &rcu_torture_reader_mbchk[rdrchker];
	if (rdrchked != myid && rdrchked != rdrchker && noc >= rdrchked && noc >= rdrchker &&
	    smp_load_acquire(&rtrcp->rtc_chkrdr) < 0 && // Pairs with smp_store_release below.
	    !READ_ONCE(rtp->rtort_chkp) &&
	    !smp_load_acquire(&rtrcp_chker->rtc_assigner)) { // Pairs with smp_store_release below.
		rtrcp->rtc_chkloops = READ_ONCE(rtrcp_chked->rtc_myloops);
		WARN_ON_ONCE(rtrcp->rtc_chkrdr >= 0);
		rtrcp->rtc_chkrdr = rdrchked;
		WARN_ON_ONCE(rtrcp->rtc_ready); // This gets set after the grace period ends.
		if (cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, NULL, rtrcp) ||
		    cmpxchg_relaxed(&rtp->rtort_chkp, NULL, rtrcp))
			(void)cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, rtrcp, NULL); // Back out.
	}

	// If assigned some completed work, do it!
	rtrcp_assigner = READ_ONCE(rtrcp->rtc_assigner);
	if (!rtrcp_assigner || !smp_load_acquire(&rtrcp_assigner->rtc_ready))
		return; // No work or work not yet ready.
	rdrchked = rtrcp_assigner->rtc_chkrdr;
	if (WARN_ON_ONCE(rdrchked < 0))
		return;
	rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
	loops = READ_ONCE(rtrcp_chked->rtc_myloops);
	atomic_inc(&n_rcu_torture_mbchk_tries);
	if (ULONG_CMP_LT(loops, rtrcp_assigner->rtc_chkloops))
		atomic_inc(&n_rcu_torture_mbchk_fail);
	rtrcp_assigner->rtc_chkloops = loops + ULONG_MAX / 2;
	rtrcp_assigner->rtc_ready = 0;
	smp_store_release(&rtrcp->rtc_assigner, NULL); // Someone else can assign us work.
	smp_store_release(&rtrcp_assigner->rtc_chkrdr, -1); // Assigner can again assign.
}

/*
 * Do one extension of an RCU read-side critical section using the
 * current reader state in readstate (set to zero for initial entry
 * to extended critical section), set the new state as specified by
 * newstate (set to zero for final exit from extended critical section),
 * and random-number-generator state in trsp.  If this is neither the
 * beginning or end of the critical section and if there was actually a
 * change, do a ->read_delay().
 */
static void rcutorture_one_extend(int *readstate, int newstate,
				  struct torture_random_state *trsp,
				  struct rt_read_seg *rtrsp)
{
	unsigned long flags;
	int idxnew = -1;
	int idxold = *readstate;
	int statesnew = ~*readstate & newstate;
	int statesold = *readstate & ~newstate;

	WARN_ON_ONCE(idxold < 0);
	WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
	rtrsp->rt_readstate = newstate;

	/* First, put new protection in place to avoid critical-section gap. */
	if (statesnew & RCUTORTURE_RDR_BH)
		local_bh_disable();
	if (statesnew & RCUTORTURE_RDR_IRQ)
		local_irq_disable();
	if (statesnew & RCUTORTURE_RDR_PREEMPT)
		preempt_disable();
	if (statesnew & RCUTORTURE_RDR_RBH)
		rcu_read_lock_bh();
	if (statesnew & RCUTORTURE_RDR_SCHED)
		rcu_read_lock_sched();
	if (statesnew & RCUTORTURE_RDR_RCU)
		idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;

	/* Next, remove old protection, irq first due to bh conflict. */
	if (statesold & RCUTORTURE_RDR_IRQ)
		local_irq_enable();
	if (statesold & RCUTORTURE_RDR_BH)
		local_bh_enable();
	if (statesold & RCUTORTURE_RDR_PREEMPT)
		preempt_enable();
	if (statesold & RCUTORTURE_RDR_RBH)
		rcu_read_unlock_bh();
	if (statesold & RCUTORTURE_RDR_SCHED)
		rcu_read_unlock_sched();
	if (statesold & RCUTORTURE_RDR_RCU) {
		bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);

		if (lockit)
			raw_spin_lock_irqsave(&current->pi_lock, flags);
		cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
		if (lockit)
			raw_spin_unlock_irqrestore(&current->pi_lock, flags);
	}

	/* Delay if neither beginning nor end and there was a change. */
	if ((statesnew || statesold) && *readstate && newstate)
		cur_ops->read_delay(trsp, rtrsp);

	/* Update the reader state. */
	if (idxnew == -1)
		idxnew = idxold & ~RCUTORTURE_RDR_MASK;
	WARN_ON_ONCE(idxnew < 0);
	WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
	*readstate = idxnew | newstate;
	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
}

/* Return the biggest extendables mask given current RCU and boot parameters. */
static int rcutorture_extend_mask_max(void)
{
	int mask;

	WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
	mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
	mask = mask | RCUTORTURE_RDR_RCU;
	return mask;
}

/* Return a random protection state mask, but with at least one bit set. */
static int
rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
{
	int mask = rcutorture_extend_mask_max();
	unsigned long randmask1 = torture_random(trsp) >> 8;
	unsigned long randmask2 = randmask1 >> 3;

	WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
	/* Mostly only one bit (need preemption!), sometimes lots of bits. */
	if (!(randmask1 & 0x7))
		mask = mask & randmask2;
	else
		mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
	/* Can't enable bh w/irq disabled. */
	if ((mask & RCUTORTURE_RDR_IRQ) &&
	    ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
	     (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
		mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
	return mask ?: RCUTORTURE_RDR_RCU;
}

/*
 * Do a randomly selected number of extensions of an existing RCU read-side
 * critical section.
 */
static struct rt_read_seg *
rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
		       struct rt_read_seg *rtrsp)
{
	int i;
	int j;
	int mask = rcutorture_extend_mask_max();

	WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
	if (!((mask - 1) & mask))
		return rtrsp;  /* Current RCU reader not extendable. */
	/* Bias towards larger numbers of loops. */
	i = (torture_random(trsp) >> 3);
	i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
	for (j = 0; j < i; j++) {
		mask = rcutorture_extend_mask(*readstate, trsp);
		rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
	}
	return &rtrsp[j];
}

/*
 * Do one read-side critical section, returning false if there was
 * no data to read.  Can be invoked both from process context and
 * from a timer handler.
 */
static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
{
	unsigned long cookie;
	int i;
	unsigned long started;
	unsigned long completed;
	int newstate;
	struct rcu_torture *p;
	int pipe_count;
	int readstate = 0;
	struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
	struct rt_read_seg *rtrsp = &rtseg[0];
	struct rt_read_seg *rtrsp1;
	unsigned long long ts;

	WARN_ON_ONCE(!rcu_is_watching());
	newstate = rcutorture_extend_mask(readstate, trsp);
	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
		cookie = cur_ops->get_gp_state();
	started = cur_ops->get_gp_seq();
	ts = rcu_trace_clock_local();
	p = rcu_dereference_check(rcu_torture_current,
				  !cur_ops->readlock_held || cur_ops->readlock_held());
	if (p == NULL) {
		/* Wait for rcu_torture_writer to get underway */
		rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
		return false;
	}
	if (p->rtort_mbtest == 0)
		atomic_inc(&n_rcu_torture_mberror);
	rcu_torture_reader_do_mbchk(myid, p, trsp);
	rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
	preempt_disable();
	pipe_count = READ_ONCE(p->rtort_pipe_count);
	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
		/* Should not happen, but... */
		pipe_count = RCU_TORTURE_PIPE_LEN;
	}
	completed = cur_ops->get_gp_seq();
	if (pipe_count > 1) {
		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
					  ts, started, completed);
		rcu_ftrace_dump(DUMP_ALL);
	}
	__this_cpu_inc(rcu_torture_count[pipe_count]);
	completed = rcutorture_seq_diff(completed, started);
	if (completed > RCU_TORTURE_PIPE_LEN) {
		/* Should not happen, but... */
		completed = RCU_TORTURE_PIPE_LEN;
	}
	__this_cpu_inc(rcu_torture_batch[completed]);
	preempt_enable();
	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
		WARN_ONCE(cur_ops->poll_gp_state(cookie),
			  "%s: Cookie check 2 failed %s(%d) %lu->%lu\n",
			  __func__,
			  rcu_torture_writer_state_getname(),
			  rcu_torture_writer_state,
			  cookie, cur_ops->get_gp_state());
	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
	// This next splat is expected behavior if leakpointer, especially
	// for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
	WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);

	/* If error or close call, record the sequence of reader protections. */
	if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
		i = 0;
		for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
			err_segs[i++] = *rtrsp1;
		rt_read_nsegs = i;
	}

	return true;
}

static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);

/*
 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 * incrementing the corresponding element of the pipeline array.  The
 * counter in the element should never be greater than 1, otherwise, the
 * RCU implementation is broken.
 */
static void rcu_torture_timer(struct timer_list *unused)
{
	atomic_long_inc(&n_rcu_torture_timers);
	(void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand), -1);

	/* Test call_rcu() invocation from interrupt handler. */
	if (cur_ops->call) {
		struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);

		if (rhp)
			cur_ops->call(rhp, rcu_torture_timer_cb);
	}
}

/*
 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 * incrementing the corresponding element of the pipeline array.  The
 * counter in the element should never be greater than 1, otherwise, the
 * RCU implementation is broken.
 */
static int
rcu_torture_reader(void *arg)
{
	unsigned long lastsleep = jiffies;
	long myid = (long)arg;
	int mynumonline = myid;
	DEFINE_TORTURE_RANDOM(rand);
	struct timer_list t;

	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
	set_user_nice(current, MAX_NICE);
	if (irqreader && cur_ops->irq_capable)
		timer_setup_on_stack(&t, rcu_torture_timer, 0);
	tick_dep_set_task(current, TICK_DEP_BIT_RCU);
	do {
		if (irqreader && cur_ops->irq_capable) {
			if (!timer_pending(&t))
				mod_timer(&t, jiffies + 1);
		}
		if (!rcu_torture_one_read(&rand, myid) && !torture_must_stop())
			schedule_timeout_interruptible(HZ);
		if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
			torture_hrtimeout_us(500, 1000, &rand);
			lastsleep = jiffies + 10;
		}
		while (torture_num_online_cpus() < mynumonline && !torture_must_stop())
			schedule_timeout_interruptible(HZ / 5);
		stutter_wait("rcu_torture_reader");
	} while (!torture_must_stop());
	if (irqreader && cur_ops->irq_capable) {
		del_timer_sync(&t);
		destroy_timer_on_stack(&t);
	}
	tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
	torture_kthread_stopping("rcu_torture_reader");
	return 0;
}

/*
 * Randomly Toggle CPUs' callback-offload state.  This uses hrtimers to
 * increase race probabilities and fuzzes the interval between toggling.
 */
static int rcu_nocb_toggle(void *arg)
{
	int cpu;
	int maxcpu = -1;
	int oldnice = task_nice(current);
	long r;
	DEFINE_TORTURE_RANDOM(rand);
	ktime_t toggle_delay;
	unsigned long toggle_fuzz;
	ktime_t toggle_interval = ms_to_ktime(nocbs_toggle);

	VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started");
	while (!rcu_inkernel_boot_has_ended())
		schedule_timeout_interruptible(HZ / 10);
	for_each_online_cpu(cpu)
		maxcpu = cpu;
	WARN_ON(maxcpu < 0);
	if (toggle_interval > ULONG_MAX)
		toggle_fuzz = ULONG_MAX >> 3;
	else
		toggle_fuzz = toggle_interval >> 3;
	if (toggle_fuzz <= 0)
		toggle_fuzz = NSEC_PER_USEC;
	do {
		r = torture_random(&rand);
		cpu = (r >> 4) % (maxcpu + 1);
		if (r & 0x1) {
			rcu_nocb_cpu_offload(cpu);
			atomic_long_inc(&n_nocb_offload);
		} else {
			rcu_nocb_cpu_deoffload(cpu);
			atomic_long_inc(&n_nocb_deoffload);
		}
		toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
		set_current_state(TASK_INTERRUPTIBLE);
		schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
		if (stutter_wait("rcu_nocb_toggle"))
			sched_set_normal(current, oldnice);
	} while (!torture_must_stop());
	torture_kthread_stopping("rcu_nocb_toggle");
	return 0;
}

/*
 * Print torture statistics.  Caller must ensure that there is only
 * one call to this function at a given time!!!  This is normally
 * accomplished by relying on the module system to only have one copy
 * of the module loaded, and then by giving the rcu_torture_stats
 * kthread full control (or the init/cleanup functions when rcu_torture_stats
 * thread is not running).
 */
static void
rcu_torture_stats_print(void)
{
	int cpu;
	int i;
	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
	struct rcu_torture *rtcp;
	static unsigned long rtcv_snap = ULONG_MAX;
	static bool splatted;
	struct task_struct *wtp;

	for_each_possible_cpu(cpu) {
		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
			pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
			batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
		}
	}
	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
		if (pipesummary[i] != 0)
			break;
	}

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	rtcp = rcu_access_pointer(rcu_torture_current);
	pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
		rtcp,
		rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
		rcu_torture_current_version,
		list_empty(&rcu_torture_freelist),
		atomic_read(&n_rcu_torture_alloc),
		atomic_read(&n_rcu_torture_alloc_fail),
		atomic_read(&n_rcu_torture_free));
	pr_cont("rtmbe: %d rtmbkf: %d/%d rtbe: %ld rtbke: %ld rtbre: %ld ",
		atomic_read(&n_rcu_torture_mberror),
		atomic_read(&n_rcu_torture_mbchk_fail), atomic_read(&n_rcu_torture_mbchk_tries),
		n_rcu_torture_barrier_error,
		n_rcu_torture_boost_ktrerror,
		n_rcu_torture_boost_rterror);
	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
		n_rcu_torture_boost_failure,
		n_rcu_torture_boosts,
		atomic_long_read(&n_rcu_torture_timers));
	torture_onoff_stats();
	pr_cont("barrier: %ld/%ld:%ld ",
		data_race(n_barrier_successes),
		data_race(n_barrier_attempts),
		data_race(n_rcu_torture_barrier_error));
	pr_cont("read-exits: %ld ", data_race(n_read_exits)); // Statistic.
	pr_cont("nocb-toggles: %ld:%ld\n",
		atomic_long_read(&n_nocb_offload), atomic_long_read(&n_nocb_deoffload));

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	if (atomic_read(&n_rcu_torture_mberror) ||
	    atomic_read(&n_rcu_torture_mbchk_fail) ||
	    n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
	    n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
	    i > 1) {
		pr_cont("%s", "!!! ");
		atomic_inc(&n_rcu_torture_error);
		WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
		WARN_ON_ONCE(atomic_read(&n_rcu_torture_mbchk_fail));
		WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
		WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
		WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
		WARN_ON_ONCE(n_rcu_torture_boost_failure); // boost failed (TIMER_SOFTIRQ RT prio?)
		WARN_ON_ONCE(i > 1); // Too-short grace period
	}
	pr_cont("Reader Pipe: ");
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
		pr_cont(" %ld", pipesummary[i]);
	pr_cont("\n");

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	pr_cont("Reader Batch: ");
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
		pr_cont(" %ld", batchsummary[i]);
	pr_cont("\n");

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	pr_cont("Free-Block Circulation: ");
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
	}
	pr_cont("\n");

	if (cur_ops->stats)
		cur_ops->stats();
	if (rtcv_snap == rcu_torture_current_version &&
	    rcu_access_pointer(rcu_torture_current) &&
	    !rcu_stall_is_suppressed()) {
		int __maybe_unused flags = 0;
		unsigned long __maybe_unused gp_seq = 0;

		rcutorture_get_gp_data(cur_ops->ttype,
				       &flags, &gp_seq);
		srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
					&flags, &gp_seq);
		wtp = READ_ONCE(writer_task);
		pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
			 rcu_torture_writer_state_getname(),
			 rcu_torture_writer_state, gp_seq, flags,
			 wtp == NULL ? ~0U : wtp->__state,
			 wtp == NULL ? -1 : (int)task_cpu(wtp));
		if (!splatted && wtp) {
			sched_show_task(wtp);
			splatted = true;
		}
		if (cur_ops->gp_kthread_dbg)
			cur_ops->gp_kthread_dbg();
		rcu_ftrace_dump(DUMP_ALL);
	}
	rtcv_snap = rcu_torture_current_version;
}

/*
 * Periodically prints torture statistics, if periodic statistics printing
 * was specified via the stat_interval module parameter.
 */
static int
rcu_torture_stats(void *arg)
{
	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
	do {
		schedule_timeout_interruptible(stat_interval * HZ);
		rcu_torture_stats_print();
		torture_shutdown_absorb("rcu_torture_stats");
	} while (!torture_must_stop());
	torture_kthread_stopping("rcu_torture_stats");
	return 0;
}

/* Test mem_dump_obj() and friends.  */
static void rcu_torture_mem_dump_obj(void)
{
	struct rcu_head *rhp;
	struct kmem_cache *kcp;
	static int z;

	kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
	rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
	pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
	pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
	mem_dump_obj(ZERO_SIZE_PTR);
	pr_alert("mem_dump_obj(NULL):");
	mem_dump_obj(NULL);
	pr_alert("mem_dump_obj(%px):", &rhp);
	mem_dump_obj(&rhp);
	pr_alert("mem_dump_obj(%px):", rhp);
	mem_dump_obj(rhp);
	pr_alert("mem_dump_obj(%px):", &rhp->func);
	mem_dump_obj(&rhp->func);
	pr_alert("mem_dump_obj(%px):", &z);
	mem_dump_obj(&z);
	kmem_cache_free(kcp, rhp);
	kmem_cache_destroy(kcp);
	rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
	pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
	pr_alert("mem_dump_obj(kmalloc %px):", rhp);
	mem_dump_obj(rhp);
	pr_alert("mem_dump_obj(kmalloc %px):", &rhp->func);
	mem_dump_obj(&rhp->func);
	kfree(rhp);
	rhp = vmalloc(4096);
	pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
	pr_alert("mem_dump_obj(vmalloc %px):", rhp);
	mem_dump_obj(rhp);
	pr_alert("mem_dump_obj(vmalloc %px):", &rhp->func);
	mem_dump_obj(&rhp->func);
	vfree(rhp);
}

static void
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
{
	pr_alert("%s" TORTURE_FLAG
		 "--- %s: nreaders=%d nfakewriters=%d "
		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
		 "shuffle_interval=%d stutter=%d irqreader=%d "
		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
		 "test_boost=%d/%d test_boost_interval=%d "
		 "test_boost_duration=%d shutdown_secs=%d "
		 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
		 "stall_cpu_block=%d "
		 "n_barrier_cbs=%d "
		 "onoff_interval=%d onoff_holdoff=%d "
		 "read_exit_delay=%d read_exit_burst=%d "
		 "nocbs_nthreads=%d nocbs_toggle=%d\n",
		 torture_type, tag, nrealreaders, nfakewriters,
		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
		 test_boost, cur_ops->can_boost,
		 test_boost_interval, test_boost_duration, shutdown_secs,
		 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
		 stall_cpu_block,
		 n_barrier_cbs,
		 onoff_interval, onoff_holdoff,
		 read_exit_delay, read_exit_burst,
		 nocbs_nthreads, nocbs_toggle);
}

static int rcutorture_booster_cleanup(unsigned int cpu)
{
	struct task_struct *t;

	if (boost_tasks[cpu] == NULL)
		return 0;
	mutex_lock(&boost_mutex);
	t = boost_tasks[cpu];
	boost_tasks[cpu] = NULL;
	rcu_torture_enable_rt_throttle();
	mutex_unlock(&boost_mutex);

	/* This must be outside of the mutex, otherwise deadlock! */
	torture_stop_kthread(rcu_torture_boost, t);
	return 0;
}

static int rcutorture_booster_init(unsigned int cpu)
{
	int retval;

	if (boost_tasks[cpu] != NULL)
		return 0;  /* Already created, nothing more to do. */

	/* Don't allow time recalculation while creating a new task. */
	mutex_lock(&boost_mutex);
	rcu_torture_disable_rt_throttle();
	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
						  cpu_to_node(cpu),
						  "rcu_torture_boost");
	if (IS_ERR(boost_tasks[cpu])) {
		retval = PTR_ERR(boost_tasks[cpu]);
		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
		n_rcu_torture_boost_ktrerror++;
		boost_tasks[cpu] = NULL;
		mutex_unlock(&boost_mutex);
		return retval;
	}
	kthread_bind(boost_tasks[cpu], cpu);
	wake_up_process(boost_tasks[cpu]);
	mutex_unlock(&boost_mutex);
	return 0;
}

/*
 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
 * induces a CPU stall for the time specified by stall_cpu.
 */
static int rcu_torture_stall(void *args)
{
	int idx;
	unsigned long stop_at;

	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
	if (stall_cpu_holdoff > 0) {
		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
	}
	if (!kthread_should_stop() && stall_gp_kthread > 0) {
		VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
		rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
		for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
			if (kthread_should_stop())
				break;
			schedule_timeout_uninterruptible(HZ);
		}
	}
	if (!kthread_should_stop() && stall_cpu > 0) {
		VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
		stop_at = ktime_get_seconds() + stall_cpu;
		/* RCU CPU stall is expected behavior in following code. */
		idx = cur_ops->readlock();
		if (stall_cpu_irqsoff)
			local_irq_disable();
		else if (!stall_cpu_block)
			preempt_disable();
		pr_alert("%s start on CPU %d.\n",
			  __func__, raw_smp_processor_id());
		while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
				    stop_at))
			if (stall_cpu_block) {
#ifdef CONFIG_PREEMPTION
				preempt_schedule();
#else
				schedule_timeout_uninterruptible(HZ);
#endif
			}
		if (stall_cpu_irqsoff)
			local_irq_enable();
		else if (!stall_cpu_block)
			preempt_enable();
		cur_ops->readunlock(idx);
	}
	pr_alert("%s end.\n", __func__);
	torture_shutdown_absorb("rcu_torture_stall");
	while (!kthread_should_stop())
		schedule_timeout_interruptible(10 * HZ);
	return 0;
}

/* Spawn CPU-stall kthread, if stall_cpu specified. */
static int __init rcu_torture_stall_init(void)
{
	if (stall_cpu <= 0 && stall_gp_kthread <= 0)
		return 0;
	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
}

/* State structure for forward-progress self-propagating RCU callback. */
struct fwd_cb_state {
	struct rcu_head rh;
	int stop;
};

/*
 * Forward-progress self-propagating RCU callback function.  Because
 * callbacks run from softirq, this function is an implicit RCU read-side
 * critical section.
 */
static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
{
	struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);

	if (READ_ONCE(fcsp->stop)) {
		WRITE_ONCE(fcsp->stop, 2);
		return;
	}
	cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
}

/* State for continuous-flood RCU callbacks. */
struct rcu_fwd_cb {
	struct rcu_head rh;
	struct rcu_fwd_cb *rfc_next;
	struct rcu_fwd *rfc_rfp;
	int rfc_gps;
};

#define MAX_FWD_CB_JIFFIES	(8 * HZ) /* Maximum CB test duration. */
#define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */
#define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */
#define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */
#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))

struct rcu_launder_hist {
	long n_launders;
	unsigned long launder_gp_seq;
};

struct rcu_fwd {
	spinlock_t rcu_fwd_lock;
	struct rcu_fwd_cb *rcu_fwd_cb_head;
	struct rcu_fwd_cb **rcu_fwd_cb_tail;
	long n_launders_cb;
	unsigned long rcu_fwd_startat;
	struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
	unsigned long rcu_launder_gp_seq_start;
};

static DEFINE_MUTEX(rcu_fwd_mutex);
static struct rcu_fwd *rcu_fwds;
static bool rcu_fwd_emergency_stop;

static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
{
	unsigned long gps;
	unsigned long gps_old;
	int i;
	int j;

	for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
		if (rfp->n_launders_hist[i].n_launders > 0)
			break;
	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
		 __func__, jiffies - rfp->rcu_fwd_startat);
	gps_old = rfp->rcu_launder_gp_seq_start;
	for (j = 0; j <= i; j++) {
		gps = rfp->n_launders_hist[j].launder_gp_seq;
		pr_cont(" %ds/%d: %ld:%ld",
			j + 1, FWD_CBS_HIST_DIV,
			rfp->n_launders_hist[j].n_launders,
			rcutorture_seq_diff(gps, gps_old));
		gps_old = gps;
	}
	pr_cont("\n");
}

/* Callback function for continuous-flood RCU callbacks. */
static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
{
	unsigned long flags;
	int i;
	struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
	struct rcu_fwd_cb **rfcpp;
	struct rcu_fwd *rfp = rfcp->rfc_rfp;

	rfcp->rfc_next = NULL;
	rfcp->rfc_gps++;
	spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
	rfcpp = rfp->rcu_fwd_cb_tail;
	rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
	WRITE_ONCE(*rfcpp, rfcp);
	WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
	i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
	if (i >= ARRAY_SIZE(rfp->n_launders_hist))
		i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
	rfp->n_launders_hist[i].n_launders++;
	rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
	spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
}

// Give the scheduler a chance, even on nohz_full CPUs.
static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
{
	if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
		// Real call_rcu() floods hit userspace, so emulate that.
		if (need_resched() || (iter & 0xfff))
			schedule();
		return;
	}
	// No userspace emulation: CB invocation throttles call_rcu()
	cond_resched();
}

/*
 * Free all callbacks on the rcu_fwd_cb_head list, either because the
 * test is over or because we hit an OOM event.
 */
static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
{
	unsigned long flags;
	unsigned long freed = 0;
	struct rcu_fwd_cb *rfcp;

	for (;;) {
		spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
		rfcp = rfp->rcu_fwd_cb_head;
		if (!rfcp) {
			spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
			break;
		}
		rfp->rcu_fwd_cb_head = rfcp->rfc_next;
		if (!rfp->rcu_fwd_cb_head)
			rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
		spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
		kfree(rfcp);
		freed++;
		rcu_torture_fwd_prog_cond_resched(freed);
		if (tick_nohz_full_enabled()) {
			local_irq_save(flags);
			rcu_momentary_dyntick_idle();
			local_irq_restore(flags);
		}
	}
	return freed;
}

/* Carry out need_resched()/cond_resched() forward-progress testing. */
static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
				    int *tested, int *tested_tries)
{
	unsigned long cver;
	unsigned long dur;
	struct fwd_cb_state fcs;
	unsigned long gps;
	int idx;
	int sd;
	int sd4;
	bool selfpropcb = false;
	unsigned long stopat;
	static DEFINE_TORTURE_RANDOM(trs);

	if (!cur_ops->sync)
		return; // Cannot do need_resched() forward progress testing without ->sync.
	if (cur_ops->call && cur_ops->cb_barrier) {
		init_rcu_head_on_stack(&fcs.rh);
		selfpropcb = true;
	}

	/* Tight loop containing cond_resched(). */
	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
	cur_ops->sync(); /* Later readers see above write. */
	if  (selfpropcb) {
		WRITE_ONCE(fcs.stop, 0);
		cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
	}
	cver = READ_ONCE(rcu_torture_current_version);
	gps = cur_ops->get_gp_seq();
	sd = cur_ops->stall_dur() + 1;
	sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
	dur = sd4 + torture_random(&trs) % (sd - sd4);
	WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
	stopat = rfp->rcu_fwd_startat + dur;
	while (time_before(jiffies, stopat) &&
	       !shutdown_time_arrived() &&
	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
		idx = cur_ops->readlock();
		udelay(10);
		cur_ops->readunlock(idx);
		if (!fwd_progress_need_resched || need_resched())
			cond_resched();
	}
	(*tested_tries)++;
	if (!time_before(jiffies, stopat) &&
	    !shutdown_time_arrived() &&
	    !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
		(*tested)++;
		cver = READ_ONCE(rcu_torture_current_version) - cver;
		gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
		WARN_ON(!cver && gps < 2);
		pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
	}
	if (selfpropcb) {
		WRITE_ONCE(fcs.stop, 1);
		cur_ops->sync(); /* Wait for running CB to complete. */
		cur_ops->cb_barrier(); /* Wait for queued callbacks. */
	}

	if (selfpropcb) {
		WARN_ON(READ_ONCE(fcs.stop) != 2);
		destroy_rcu_head_on_stack(&fcs.rh);
	}
	schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
}

/* Carry out call_rcu() forward-progress testing. */
static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
{
	unsigned long cver;
	unsigned long flags;
	unsigned long gps;
	int i;
	long n_launders;
	long n_launders_cb_snap;
	long n_launders_sa;
	long n_max_cbs;
	long n_max_gps;
	struct rcu_fwd_cb *rfcp;
	struct rcu_fwd_cb *rfcpn;
	unsigned long stopat;
	unsigned long stoppedat;

	if (READ_ONCE(rcu_fwd_emergency_stop))
		return; /* Get out of the way quickly, no GP wait! */
	if (!cur_ops->call)
		return; /* Can't do call_rcu() fwd prog without ->call. */

	/* Loop continuously posting RCU callbacks. */
	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
	cur_ops->sync(); /* Later readers see above write. */
	WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
	stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
	n_launders = 0;
	rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
	n_launders_sa = 0;
	n_max_cbs = 0;
	n_max_gps = 0;
	for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
		rfp->n_launders_hist[i].n_launders = 0;
	cver = READ_ONCE(rcu_torture_current_version);
	gps = cur_ops->get_gp_seq();
	rfp->rcu_launder_gp_seq_start = gps;
	tick_dep_set_task(current, TICK_DEP_BIT_RCU);
	while (time_before(jiffies, stopat) &&
	       !shutdown_time_arrived() &&
	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
		rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
		rfcpn = NULL;
		if (rfcp)
			rfcpn = READ_ONCE(rfcp->rfc_next);
		if (rfcpn) {
			if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
			    ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
				break;
			rfp->rcu_fwd_cb_head = rfcpn;
			n_launders++;
			n_launders_sa++;
		} else {
			rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
			if (WARN_ON_ONCE(!rfcp)) {
				schedule_timeout_interruptible(1);
				continue;
			}
			n_max_cbs++;
			n_launders_sa = 0;
			rfcp->rfc_gps = 0;
			rfcp->rfc_rfp = rfp;
		}
		cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
		rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
		if (tick_nohz_full_enabled()) {
			local_irq_save(flags);
			rcu_momentary_dyntick_idle();
			local_irq_restore(flags);
		}
	}
	stoppedat = jiffies;
	n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
	cver = READ_ONCE(rcu_torture_current_version) - cver;
	gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
	cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
	(void)rcu_torture_fwd_prog_cbfree(rfp);

	if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
	    !shutdown_time_arrived()) {
		WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
		pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
			 __func__,
			 stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
			 n_launders + n_max_cbs - n_launders_cb_snap,
			 n_launders, n_launders_sa,
			 n_max_gps, n_max_cbs, cver, gps);
		rcu_torture_fwd_cb_hist(rfp);
	}
	schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
	tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
}


/*
 * OOM notifier, but this only prints diagnostic information for the
 * current forward-progress test.
 */
static int rcutorture_oom_notify(struct notifier_block *self,
				 unsigned long notused, void *nfreed)
{
	struct rcu_fwd *rfp;

	mutex_lock(&rcu_fwd_mutex);
	rfp = rcu_fwds;
	if (!rfp) {
		mutex_unlock(&rcu_fwd_mutex);
		return NOTIFY_OK;
	}
	WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
	     __func__);
	rcu_torture_fwd_cb_hist(rfp);
	rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
	WRITE_ONCE(rcu_fwd_emergency_stop, true);
	smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
	pr_info("%s: Freed %lu RCU callbacks.\n",
		__func__, rcu_torture_fwd_prog_cbfree(rfp));
	rcu_barrier();
	pr_info("%s: Freed %lu RCU callbacks.\n",
		__func__, rcu_torture_fwd_prog_cbfree(rfp));
	rcu_barrier();
	pr_info("%s: Freed %lu RCU callbacks.\n",
		__func__, rcu_torture_fwd_prog_cbfree(rfp));
	smp_mb(); /* Frees before return to avoid redoing OOM. */
	(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
	pr_info("%s returning after OOM processing.\n", __func__);
	mutex_unlock(&rcu_fwd_mutex);
	return NOTIFY_OK;
}

static struct notifier_block rcutorture_oom_nb = {
	.notifier_call = rcutorture_oom_notify
};

/* Carry out grace-period forward-progress testing. */
static int rcu_torture_fwd_prog(void *args)
{
	int oldnice = task_nice(current);
	struct rcu_fwd *rfp = args;
	int tested = 0;
	int tested_tries = 0;

	VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
	rcu_bind_current_to_nocb();
	if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
		set_user_nice(current, MAX_NICE);
	do {
		schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
		WRITE_ONCE(rcu_fwd_emergency_stop, false);
		if (!IS_ENABLED(CONFIG_TINY_RCU) ||
		    rcu_inkernel_boot_has_ended())
			rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
		if (rcu_inkernel_boot_has_ended())
			rcu_torture_fwd_prog_cr(rfp);

		/* Avoid slow periods, better to test when busy. */
		if (stutter_wait("rcu_torture_fwd_prog"))
			sched_set_normal(current, oldnice);
	} while (!torture_must_stop());
	/* Short runs might not contain a valid forward-progress attempt. */
	WARN_ON(!tested && tested_tries >= 5);
	pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
	torture_kthread_stopping("rcu_torture_fwd_prog");
	return 0;
}

/* If forward-progress checking is requested and feasible, spawn the thread. */
static int __init rcu_torture_fwd_prog_init(void)
{
	struct rcu_fwd *rfp;

	if (!fwd_progress)
		return 0; /* Not requested, so don't do it. */
	if ((!cur_ops->sync && !cur_ops->call) ||
	    !cur_ops->stall_dur || cur_ops->stall_dur() <= 0 || cur_ops == &rcu_busted_ops) {
		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
		return 0;
	}
	if (stall_cpu > 0) {
		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
		if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
			return -EINVAL; /* In module, can fail back to user. */
		WARN_ON(1); /* Make sure rcutorture notices conflict. */
		return 0;
	}
	if (fwd_progress_holdoff <= 0)
		fwd_progress_holdoff = 1;
	if (fwd_progress_div <= 0)
		fwd_progress_div = 4;
	rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
	if (!rfp)
		return -ENOMEM;
	spin_lock_init(&rfp->rcu_fwd_lock);
	rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
	mutex_lock(&rcu_fwd_mutex);
	rcu_fwds = rfp;
	mutex_unlock(&rcu_fwd_mutex);
	register_oom_notifier(&rcutorture_oom_nb);
	return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
}

static void rcu_torture_fwd_prog_cleanup(void)
{
	struct rcu_fwd *rfp;

	torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
	rfp = rcu_fwds;
	mutex_lock(&rcu_fwd_mutex);
	rcu_fwds = NULL;
	mutex_unlock(&rcu_fwd_mutex);
	unregister_oom_notifier(&rcutorture_oom_nb);
	kfree(rfp);
}

/* Callback function for RCU barrier testing. */
static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
{
	atomic_inc(&barrier_cbs_invoked);
}

/* IPI handler to get callback posted on desired CPU, if online. */
static void rcu_torture_barrier1cb(void *rcu_void)
{
	struct rcu_head *rhp = rcu_void;

	cur_ops->call(rhp, rcu_torture_barrier_cbf);
}

/* kthread function to register callbacks used to test RCU barriers. */
static int rcu_torture_barrier_cbs(void *arg)
{
	long myid = (long)arg;
	bool lastphase = false;
	bool newphase;
	struct rcu_head rcu;

	init_rcu_head_on_stack(&rcu);
	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
	set_user_nice(current, MAX_NICE);
	do {
		wait_event(barrier_cbs_wq[myid],
			   (newphase =
			    smp_load_acquire(&barrier_phase)) != lastphase ||
			   torture_must_stop());
		lastphase = newphase;
		if (torture_must_stop())
			break;
		/*
		 * The above smp_load_acquire() ensures barrier_phase load
		 * is ordered before the following ->call().
		 */
		if (smp_call_function_single(myid, rcu_torture_barrier1cb,
					     &rcu, 1)) {
			// IPI failed, so use direct call from current CPU.
			cur_ops->call(&rcu, rcu_torture_barrier_cbf);
		}
		if (atomic_dec_and_test(&barrier_cbs_count))
			wake_up(&barrier_wq);
	} while (!torture_must_stop());
	if (cur_ops->cb_barrier != NULL)
		cur_ops->cb_barrier();
	destroy_rcu_head_on_stack(&rcu);
	torture_kthread_stopping("rcu_torture_barrier_cbs");
	return 0;
}

/* kthread function to drive and coordinate RCU barrier testing. */
static int rcu_torture_barrier(void *arg)
{
	int i;

	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
	do {
		atomic_set(&barrier_cbs_invoked, 0);
		atomic_set(&barrier_cbs_count, n_barrier_cbs);
		/* Ensure barrier_phase ordered after prior assignments. */
		smp_store_release(&barrier_phase, !barrier_phase);
		for (i = 0; i < n_barrier_cbs; i++)
			wake_up(&barrier_cbs_wq[i]);
		wait_event(barrier_wq,
			   atomic_read(&barrier_cbs_count) == 0 ||
			   torture_must_stop());
		if (torture_must_stop())
			break;
		n_barrier_attempts++;
		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
			n_rcu_torture_barrier_error++;
			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
			       atomic_read(&barrier_cbs_invoked),
			       n_barrier_cbs);
			WARN_ON(1);
			// Wait manually for the remaining callbacks
			i = 0;
			do {
				if (WARN_ON(i++ > HZ))
					i = INT_MIN;
				schedule_timeout_interruptible(1);
				cur_ops->cb_barrier();
			} while (atomic_read(&barrier_cbs_invoked) !=
				 n_barrier_cbs &&
				 !torture_must_stop());
			smp_mb(); // Can't trust ordering if broken.
			if (!torture_must_stop())
				pr_err("Recovered: barrier_cbs_invoked = %d\n",
				       atomic_read(&barrier_cbs_invoked));
		} else {
			n_barrier_successes++;
		}
		schedule_timeout_interruptible(HZ / 10);
	} while (!torture_must_stop());
	torture_kthread_stopping("rcu_torture_barrier");
	return 0;
}

/* Initialize RCU barrier testing. */
static int rcu_torture_barrier_init(void)
{
	int i;
	int ret;

	if (n_barrier_cbs <= 0)
		return 0;
	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
		pr_alert("%s" TORTURE_FLAG
			 " Call or barrier ops missing for %s,\n",
			 torture_type, cur_ops->name);
		pr_alert("%s" TORTURE_FLAG
			 " RCU barrier testing omitted from run.\n",
			 torture_type);
		return 0;
	}
	atomic_set(&barrier_cbs_count, 0);
	atomic_set(&barrier_cbs_invoked, 0);
	barrier_cbs_tasks =
		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
			GFP_KERNEL);
	barrier_cbs_wq =
		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
		return -ENOMEM;
	for (i = 0; i < n_barrier_cbs; i++) {
		init_waitqueue_head(&barrier_cbs_wq[i]);
		ret = torture_create_kthread(rcu_torture_barrier_cbs,
					     (void *)(long)i,
					     barrier_cbs_tasks[i]);
		if (ret)
			return ret;
	}
	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
}

/* Clean up after RCU barrier testing. */
static void rcu_torture_barrier_cleanup(void)
{
	int i;

	torture_stop_kthread(rcu_torture_barrier, barrier_task);
	if (barrier_cbs_tasks != NULL) {
		for (i = 0; i < n_barrier_cbs; i++)
			torture_stop_kthread(rcu_torture_barrier_cbs,
					     barrier_cbs_tasks[i]);
		kfree(barrier_cbs_tasks);
		barrier_cbs_tasks = NULL;
	}
	if (barrier_cbs_wq != NULL) {
		kfree(barrier_cbs_wq);
		barrier_cbs_wq = NULL;
	}
}

static bool rcu_torture_can_boost(void)
{
	static int boost_warn_once;
	int prio;

	if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
		return false;
	if (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)
		return false;

	prio = rcu_get_gp_kthreads_prio();
	if (!prio)
		return false;

	if (prio < 2) {
		if (boost_warn_once == 1)
			return false;

		pr_alert("%s: WARN: RCU kthread priority too low to test boosting.  Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
		boost_warn_once = 1;
		return false;
	}

	return true;
}

static bool read_exit_child_stop;
static bool read_exit_child_stopped;
static wait_queue_head_t read_exit_wq;

// Child kthread which just does an rcutorture reader and exits.
static int rcu_torture_read_exit_child(void *trsp_in)
{
	struct torture_random_state *trsp = trsp_in;

	set_user_nice(current, MAX_NICE);
	// Minimize time between reading and exiting.
	while (!kthread_should_stop())
		schedule_timeout_uninterruptible(1);
	(void)rcu_torture_one_read(trsp, -1);
	return 0;
}

// Parent kthread which creates and destroys read-exit child kthreads.
static int rcu_torture_read_exit(void *unused)
{
	int count = 0;
	bool errexit = false;
	int i;
	struct task_struct *tsp;
	DEFINE_TORTURE_RANDOM(trs);

	// Allocate and initialize.
	set_user_nice(current, MAX_NICE);
	VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of test");

	// Each pass through this loop does one read-exit episode.
	do {
		if (++count > read_exit_burst) {
			VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
			rcu_barrier(); // Wait for task_struct free, avoid OOM.
			for (i = 0; i < read_exit_delay; i++) {
				schedule_timeout_uninterruptible(HZ);
				if (READ_ONCE(read_exit_child_stop))
					break;
			}
			if (!READ_ONCE(read_exit_child_stop))
				VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
			count = 0;
		}
		if (READ_ONCE(read_exit_child_stop))
			break;
		// Spawn child.
		tsp = kthread_run(rcu_torture_read_exit_child,
				     &trs, "%s",
				     "rcu_torture_read_exit_child");
		if (IS_ERR(tsp)) {
			VERBOSE_TOROUT_ERRSTRING("out of memory");
			errexit = true;
			tsp = NULL;
			break;
		}
		cond_resched();
		kthread_stop(tsp);
		n_read_exits ++;
		stutter_wait("rcu_torture_read_exit");
	} while (!errexit && !READ_ONCE(read_exit_child_stop));

	// Clean up and exit.
	smp_store_release(&read_exit_child_stopped, true); // After reaping.
	smp_mb(); // Store before wakeup.
	wake_up(&read_exit_wq);
	while (!torture_must_stop())
		schedule_timeout_uninterruptible(1);
	torture_kthread_stopping("rcu_torture_read_exit");
	return 0;
}

static int rcu_torture_read_exit_init(void)
{
	if (read_exit_burst <= 0)
		return -EINVAL;
	init_waitqueue_head(&read_exit_wq);
	read_exit_child_stop = false;
	read_exit_child_stopped = false;
	return torture_create_kthread(rcu_torture_read_exit, NULL,
				      read_exit_task);
}

static void rcu_torture_read_exit_cleanup(void)
{
	if (!read_exit_task)
		return;
	WRITE_ONCE(read_exit_child_stop, true);
	smp_mb(); // Above write before wait.
	wait_event(read_exit_wq, smp_load_acquire(&read_exit_child_stopped));
	torture_stop_kthread(rcutorture_read_exit, read_exit_task);
}

static enum cpuhp_state rcutor_hp;

static void
rcu_torture_cleanup(void)
{
	int firsttime;
	int flags = 0;
	unsigned long gp_seq = 0;
	int i;

	if (torture_cleanup_begin()) {
		if (cur_ops->cb_barrier != NULL)
			cur_ops->cb_barrier();
		return;
	}
	if (!cur_ops) {
		torture_cleanup_end();
		return;
	}

	if (cur_ops->gp_kthread_dbg)
		cur_ops->gp_kthread_dbg();
	rcu_torture_read_exit_cleanup();
	rcu_torture_barrier_cleanup();
	rcu_torture_fwd_prog_cleanup();
	torture_stop_kthread(rcu_torture_stall, stall_task);
	torture_stop_kthread(rcu_torture_writer, writer_task);

	if (nocb_tasks) {
		for (i = 0; i < nrealnocbers; i++)
			torture_stop_kthread(rcu_nocb_toggle, nocb_tasks[i]);
		kfree(nocb_tasks);
		nocb_tasks = NULL;
	}

	if (reader_tasks) {
		for (i = 0; i < nrealreaders; i++)
			torture_stop_kthread(rcu_torture_reader,
					     reader_tasks[i]);
		kfree(reader_tasks);
		reader_tasks = NULL;
	}
	kfree(rcu_torture_reader_mbchk);
	rcu_torture_reader_mbchk = NULL;

	if (fakewriter_tasks) {
		for (i = 0; i < nfakewriters; i++)
			torture_stop_kthread(rcu_torture_fakewriter,
					     fakewriter_tasks[i]);
		kfree(fakewriter_tasks);
		fakewriter_tasks = NULL;
	}

	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
	pr_alert("%s:  End-test grace-period state: g%ld f%#x total-gps=%ld\n",
		 cur_ops->name, (long)gp_seq, flags,
		 rcutorture_seq_diff(gp_seq, start_gp_seq));
	torture_stop_kthread(rcu_torture_stats, stats_task);
	torture_stop_kthread(rcu_torture_fqs, fqs_task);
	if (rcu_torture_can_boost())
		cpuhp_remove_state(rcutor_hp);

	/*
	 * Wait for all RCU callbacks to fire, then do torture-type-specific
	 * cleanup operations.
	 */
	if (cur_ops->cb_barrier != NULL)
		cur_ops->cb_barrier();
	if (cur_ops->cleanup != NULL)
		cur_ops->cleanup();

	rcu_torture_mem_dump_obj();

	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */

	if (err_segs_recorded) {
		pr_alert("Failure/close-call rcutorture reader segments:\n");
		if (rt_read_nsegs == 0)
			pr_alert("\t: No segments recorded!!!\n");
		firsttime = 1;
		for (i = 0; i < rt_read_nsegs; i++) {
			pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
			if (err_segs[i].rt_delay_jiffies != 0) {
				pr_cont("%s%ldjiffies", firsttime ? "" : "+",
					err_segs[i].rt_delay_jiffies);
				firsttime = 0;
			}
			if (err_segs[i].rt_delay_ms != 0) {
				pr_cont("%s%ldms", firsttime ? "" : "+",
					err_segs[i].rt_delay_ms);
				firsttime = 0;
			}
			if (err_segs[i].rt_delay_us != 0) {
				pr_cont("%s%ldus", firsttime ? "" : "+",
					err_segs[i].rt_delay_us);
				firsttime = 0;
			}
			pr_cont("%s\n",
				err_segs[i].rt_preempted ? "preempted" : "");

		}
	}
	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
	else if (torture_onoff_failures())
		rcu_torture_print_module_parms(cur_ops,
					       "End of test: RCU_HOTPLUG");
	else
		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
	torture_cleanup_end();
}

#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
static void rcu_torture_leak_cb(struct rcu_head *rhp)
{
}

static void rcu_torture_err_cb(struct rcu_head *rhp)
{
	/*
	 * This -might- happen due to race conditions, but is unlikely.
	 * The scenario that leads to this happening is that the
	 * first of the pair of duplicate callbacks is queued,
	 * someone else starts a grace period that includes that
	 * callback, then the second of the pair must wait for the
	 * next grace period.  Unlikely, but can happen.  If it
	 * does happen, the debug-objects subsystem won't have splatted.
	 */
	pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
}
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */

/*
 * Verify that double-free causes debug-objects to complain, but only
 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
 * cannot be carried out.
 */
static void rcu_test_debug_objects(void)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
	struct rcu_head rh1;
	struct rcu_head rh2;
	struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);

	init_rcu_head_on_stack(&rh1);
	init_rcu_head_on_stack(&rh2);
	pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);

	/* Try to queue the rh2 pair of callbacks for the same grace period. */
	preempt_disable(); /* Prevent preemption from interrupting test. */
	rcu_read_lock(); /* Make it impossible to finish a grace period. */
	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
	local_irq_disable(); /* Make it harder to start a new grace period. */
	call_rcu(&rh2, rcu_torture_leak_cb);
	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
	if (rhp) {
		call_rcu(rhp, rcu_torture_leak_cb);
		call_rcu(rhp, rcu_torture_err_cb); /* Another duplicate callback. */
	}
	local_irq_enable();
	rcu_read_unlock();
	preempt_enable();

	/* Wait for them all to get done so we can safely return. */
	rcu_barrier();
	pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
	destroy_rcu_head_on_stack(&rh1);
	destroy_rcu_head_on_stack(&rh2);
#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
	pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
}

static void rcutorture_sync(void)
{
	static unsigned long n;

	if (cur_ops->sync && !(++n & 0xfff))
		cur_ops->sync();
}

static int __init
rcu_torture_init(void)
{
	long i;
	int cpu;
	int firsterr = 0;
	int flags = 0;
	unsigned long gp_seq = 0;
	static struct rcu_torture_ops *torture_ops[] = {
		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
		&busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
		&tasks_tracing_ops, &trivial_ops,
	};

	if (!torture_init_begin(torture_type, verbose))
		return -EBUSY;

	/* Process args and tell the world that the torturer is on the job. */
	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
		cur_ops = torture_ops[i];
		if (strcmp(torture_type, cur_ops->name) == 0)
			break;
	}
	if (i == ARRAY_SIZE(torture_ops)) {
		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
			 torture_type);
		pr_alert("rcu-torture types:");
		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
			pr_cont(" %s", torture_ops[i]->name);
		pr_cont("\n");
		firsterr = -EINVAL;
		cur_ops = NULL;
		goto unwind;
	}
	if (cur_ops->fqs == NULL && fqs_duration != 0) {
		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
		fqs_duration = 0;
	}
	if (cur_ops->init)
		cur_ops->init();

	if (nreaders >= 0) {
		nrealreaders = nreaders;
	} else {
		nrealreaders = num_online_cpus() - 2 - nreaders;
		if (nrealreaders <= 0)
			nrealreaders = 1;
	}
	rcu_torture_print_module_parms(cur_ops, "Start of test");
	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
	start_gp_seq = gp_seq;
	pr_alert("%s:  Start-test grace-period state: g%ld f%#x\n",
		 cur_ops->name, (long)gp_seq, flags);

	/* Set up the freelist. */

	INIT_LIST_HEAD(&rcu_torture_freelist);
	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
		rcu_tortures[i].rtort_mbtest = 0;
		list_add_tail(&rcu_tortures[i].rtort_free,
			      &rcu_torture_freelist);
	}

	/* Initialize the statistics so that each run gets its own numbers. */

	rcu_torture_current = NULL;
	rcu_torture_current_version = 0;
	atomic_set(&n_rcu_torture_alloc, 0);
	atomic_set(&n_rcu_torture_alloc_fail, 0);
	atomic_set(&n_rcu_torture_free, 0);
	atomic_set(&n_rcu_torture_mberror, 0);
	atomic_set(&n_rcu_torture_mbchk_fail, 0);
	atomic_set(&n_rcu_torture_mbchk_tries, 0);
	atomic_set(&n_rcu_torture_error, 0);
	n_rcu_torture_barrier_error = 0;
	n_rcu_torture_boost_ktrerror = 0;
	n_rcu_torture_boost_rterror = 0;
	n_rcu_torture_boost_failure = 0;
	n_rcu_torture_boosts = 0;
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
		atomic_set(&rcu_torture_wcount[i], 0);
	for_each_possible_cpu(cpu) {
		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
			per_cpu(rcu_torture_count, cpu)[i] = 0;
			per_cpu(rcu_torture_batch, cpu)[i] = 0;
		}
	}
	err_segs_recorded = 0;
	rt_read_nsegs = 0;

	/* Start up the kthreads. */

	rcu_torture_write_types();
	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
					  writer_task);
	if (firsterr)
		goto unwind;
	if (nfakewriters > 0) {
		fakewriter_tasks = kcalloc(nfakewriters,
					   sizeof(fakewriter_tasks[0]),
					   GFP_KERNEL);
		if (fakewriter_tasks == NULL) {
			VERBOSE_TOROUT_ERRSTRING("out of memory");
			firsterr = -ENOMEM;
			goto unwind;
		}
	}
	for (i = 0; i < nfakewriters; i++) {
		firsterr = torture_create_kthread(rcu_torture_fakewriter,
						  NULL, fakewriter_tasks[i]);
		if (firsterr)
			goto unwind;
	}
	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
			       GFP_KERNEL);
	rcu_torture_reader_mbchk = kcalloc(nrealreaders, sizeof(*rcu_torture_reader_mbchk),
					   GFP_KERNEL);
	if (!reader_tasks || !rcu_torture_reader_mbchk) {
		VERBOSE_TOROUT_ERRSTRING("out of memory");
		firsterr = -ENOMEM;
		goto unwind;
	}
	for (i = 0; i < nrealreaders; i++) {
		rcu_torture_reader_mbchk[i].rtc_chkrdr = -1;
		firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
						  reader_tasks[i]);
		if (firsterr)
			goto unwind;
	}
	nrealnocbers = nocbs_nthreads;
	if (WARN_ON(nrealnocbers < 0))
		nrealnocbers = 1;
	if (WARN_ON(nocbs_toggle < 0))
		nocbs_toggle = HZ;
	if (nrealnocbers > 0) {
		nocb_tasks = kcalloc(nrealnocbers, sizeof(nocb_tasks[0]), GFP_KERNEL);
		if (nocb_tasks == NULL) {
			VERBOSE_TOROUT_ERRSTRING("out of memory");
			firsterr = -ENOMEM;
			goto unwind;
		}
	} else {
		nocb_tasks = NULL;
	}
	for (i = 0; i < nrealnocbers; i++) {
		firsterr = torture_create_kthread(rcu_nocb_toggle, NULL, nocb_tasks[i]);
		if (firsterr)
			goto unwind;
	}
	if (stat_interval > 0) {
		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
						  stats_task);
		if (firsterr)
			goto unwind;
	}
	if (test_no_idle_hz && shuffle_interval > 0) {
		firsterr = torture_shuffle_init(shuffle_interval * HZ);
		if (firsterr)
			goto unwind;
	}
	if (stutter < 0)
		stutter = 0;
	if (stutter) {
		int t;

		t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
		firsterr = torture_stutter_init(stutter * HZ, t);
		if (firsterr)
			goto unwind;
	}
	if (fqs_duration < 0)
		fqs_duration = 0;
	if (fqs_duration) {
		/* Create the fqs thread */
		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
						  fqs_task);
		if (firsterr)
			goto unwind;
	}
	if (test_boost_interval < 1)
		test_boost_interval = 1;
	if (test_boost_duration < 2)
		test_boost_duration = 2;
	if (rcu_torture_can_boost()) {

		boost_starttime = jiffies + test_boost_interval * HZ;

		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
					     rcutorture_booster_init,
					     rcutorture_booster_cleanup);
		if (firsterr < 0)
			goto unwind;
		rcutor_hp = firsterr;

		// Testing RCU priority boosting requires rcutorture do
		// some serious abuse.  Counter this by running ksoftirqd
		// at higher priority.
		if (IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)) {
			for_each_online_cpu(cpu) {
				struct sched_param sp;
				struct task_struct *t;

				t = per_cpu(ksoftirqd, cpu);
				WARN_ON_ONCE(!t);
				sp.sched_priority = 2;
				sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
			}
		}
	}
	shutdown_jiffies = jiffies + shutdown_secs * HZ;
	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
	if (firsterr)
		goto unwind;
	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
				      rcutorture_sync);
	if (firsterr)
		goto unwind;
	firsterr = rcu_torture_stall_init();
	if (firsterr)
		goto unwind;
	firsterr = rcu_torture_fwd_prog_init();
	if (firsterr)
		goto unwind;
	firsterr = rcu_torture_barrier_init();
	if (firsterr)
		goto unwind;
	firsterr = rcu_torture_read_exit_init();
	if (firsterr)
		goto unwind;
	if (object_debug)
		rcu_test_debug_objects();
	torture_init_end();
	return 0;

unwind:
	torture_init_end();
	rcu_torture_cleanup();
	if (shutdown_secs) {
		WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
		kernel_power_off();
	}
	return firsterr;
}

module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);