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authorMatthew Wilcox (Oracle) <willy@infradead.org>2023-10-04 17:53:07 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-10-18 14:34:16 -0700
commit247dbcdbf790c52fc76cf8e327cd0a5778e41e66 (patch)
tree6c11950be173d9cb443f7553eaebf3d7913062b7 /kernel
parent7a4847e54cc1889d109ce2a6ebed19aafc4a4af8 (diff)
bitops: add xor_unlock_is_negative_byte()
Replace clear_bit_and_unlock_is_negative_byte() with xor_unlock_is_negative_byte(). We have a few places that like to lock a folio, set a flag and unlock it again. Allow for the possibility of combining the latter two operations for efficiency. We are guaranteed that the caller holds the lock, so it is safe to unlock it with the xor. The caller must guarantee that nobody else will set the flag without holding the lock; it is not safe to do this with the PG_dirty flag, for example. Link: https://lkml.kernel.org/r/20231004165317.1061855-8-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kcsan/kcsan_test.c8
-rw-r--r--kernel/kcsan/selftest.c8
2 files changed, 8 insertions, 8 deletions
diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c
index 0ddbdab5903d..1333d23ac4ef 100644
--- a/kernel/kcsan/kcsan_test.c
+++ b/kernel/kcsan/kcsan_test.c
@@ -700,10 +700,10 @@ static void test_barrier_nothreads(struct kunit *test)
KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true);
-#ifdef clear_bit_unlock_is_negative_byte
- KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
- KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
- KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
+#ifdef xor_unlock_is_negative_byte
+ KCSAN_EXPECT_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
+ KCSAN_EXPECT_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
+ KCSAN_EXPECT_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
#endif
kcsan_nestable_atomic_end();
}
diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c
index 8679322450f2..619be7417420 100644
--- a/kernel/kcsan/selftest.c
+++ b/kernel/kcsan/selftest.c
@@ -228,10 +228,10 @@ static bool __init test_barrier(void)
spin_lock(&test_spinlock);
KCSAN_CHECK_RW_BARRIER(spin_unlock(&test_spinlock));
-#ifdef clear_bit_unlock_is_negative_byte
- KCSAN_CHECK_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
- KCSAN_CHECK_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
- KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
+#ifdef xor_unlock_is_negative_byte
+ KCSAN_CHECK_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var));
+ KCSAN_CHECK_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var));
+ KCSAN_CHECK_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var));
#endif
kcsan_nestable_atomic_end();