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authorLinus Torvalds <torvalds@linux-foundation.org>2018-01-30 10:15:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-01-30 10:15:30 -0800
commitd772794637451c424729dd71690d7ac158523108 (patch)
tree1ac5db7ba0a237e519e6d123e1f95d79dc4baa34 /kernel/locking
parentc1488798adaf71461c5b679e5b54c2963be5e61c (diff)
parent475c5ee193fd682c6383b5e418e65e46a477d176 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar: "The main RCU changes in this cycle were: - Updates to use cond_resched() instead of cond_resched_rcu_qs() where feasible (currently everywhere except in kernel/rcu and in kernel/torture.c). Also a couple of fixes to avoid sending IPIs to offline CPUs. - Updates to simplify RCU's dyntick-idle handling. - Updates to remove almost all uses of smp_read_barrier_depends() and read_barrier_depends(). - Torture-test updates. - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits) torture: Save a line in stutter_wait(): while -> for torture: Eliminate torture_runnable and perf_runnable torture: Make stutter less vulnerable to compilers and races locking/locktorture: Fix num reader/writer corner cases locking/locktorture: Fix rwsem reader_delay torture: Place all torture-test modules in one MAINTAINERS group rcutorture/kvm-build.sh: Skip build directory check rcutorture: Simplify functions.sh include path rcutorture: Simplify logging rcutorture/kvm-recheck-*: Improve result directory readability check rcutorture/kvm.sh: Support execution from any directory rcutorture/kvm.sh: Use consistent help text for --qemu-args rcutorture/kvm.sh: Remove unused variable, `alldone` rcutorture: Remove unused script, config2frag.sh rcutorture/configinit: Fix build directory error message rcutorture: Preempt RCU-preempt readers more vigorously torture: Reduce #ifdefs for preempt_schedule() rcu: Remove have_rcu_nocb_mask from tree_plugin.h rcu: Add comment giving debug strategy for double call_rcu() tracing, rcu: Hide trace event rcu_nocb_wake when not used ...
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/locktorture.c108
-rw-r--r--kernel/locking/qspinlock.c12
2 files changed, 57 insertions, 63 deletions
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index f24582d4dad3..6850ffd69125 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -77,10 +77,6 @@ struct lock_stress_stats {
long n_lock_acquired;
};
-int torture_runnable = IS_ENABLED(MODULE);
-module_param(torture_runnable, int, 0444);
-MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init");
-
/* Forward reference. */
static void lock_torture_cleanup(void);
@@ -130,10 +126,8 @@ static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2000 * longdelay_ms)))
mdelay(longdelay_ms);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_lock_busted_write_unlock(void)
@@ -179,10 +173,8 @@ static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2 * shortdelay_us)))
udelay(shortdelay_us);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
@@ -352,10 +344,8 @@ static void torture_mutex_delay(struct torture_random_state *trsp)
mdelay(longdelay_ms * 5);
else
mdelay(longdelay_ms / 5);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_mutex_unlock(void) __releases(torture_mutex)
@@ -507,10 +497,8 @@ static void torture_rtmutex_delay(struct torture_random_state *trsp)
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2 * shortdelay_us)))
udelay(shortdelay_us);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
@@ -547,10 +535,8 @@ static void torture_rwsem_write_delay(struct torture_random_state *trsp)
mdelay(longdelay_ms * 10);
else
mdelay(longdelay_ms / 10);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_rwsem_up_write(void) __releases(torture_rwsem)
@@ -570,14 +556,12 @@ static void torture_rwsem_read_delay(struct torture_random_state *trsp)
/* We want a long delay occasionally to force massive contention. */
if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+ (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
mdelay(longdelay_ms * 2);
else
mdelay(longdelay_ms / 2);
-#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
- preempt_schedule(); /* Allow test to be preempted. */
-#endif
+ torture_preempt_schedule(); /* Allow test to be preempted. */
}
static void torture_rwsem_up_read(void) __releases(torture_rwsem)
@@ -715,8 +699,7 @@ static void __torture_print_stats(char *page,
{
bool fail = 0;
int i, n_stress;
- long max = 0;
- long min = statp[0].n_lock_acquired;
+ long max = 0, min = statp ? statp[0].n_lock_acquired : 0;
long long sum = 0;
n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
@@ -823,7 +806,7 @@ static void lock_torture_cleanup(void)
* such, only perform the underlying torture-specific cleanups,
* and avoid anything related to locktorture.
*/
- if (!cxt.lwsa)
+ if (!cxt.lwsa && !cxt.lrsa)
goto end;
if (writer_tasks) {
@@ -879,7 +862,7 @@ static int __init lock_torture_init(void)
&percpu_rwsem_lock_ops,
};
- if (!torture_init_begin(torture_type, verbose, &torture_runnable))
+ if (!torture_init_begin(torture_type, verbose))
return -EBUSY;
/* Process args and tell the world that the torturer is on the job. */
@@ -898,6 +881,13 @@ static int __init lock_torture_init(void)
firsterr = -EINVAL;
goto unwind;
}
+
+ if (nwriters_stress == 0 && nreaders_stress == 0) {
+ pr_alert("lock-torture: must run at least one locking thread\n");
+ firsterr = -EINVAL;
+ goto unwind;
+ }
+
if (cxt.cur_ops->init)
cxt.cur_ops->init();
@@ -921,17 +911,19 @@ static int __init lock_torture_init(void)
#endif
/* Initialize the statistics so that each run gets its own numbers. */
+ if (nwriters_stress) {
+ lock_is_write_held = 0;
+ cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL);
+ if (cxt.lwsa == NULL) {
+ VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory");
+ firsterr = -ENOMEM;
+ goto unwind;
+ }
- lock_is_write_held = 0;
- cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL);
- if (cxt.lwsa == NULL) {
- VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory");
- firsterr = -ENOMEM;
- goto unwind;
- }
- for (i = 0; i < cxt.nrealwriters_stress; i++) {
- cxt.lwsa[i].n_lock_fail = 0;
- cxt.lwsa[i].n_lock_acquired = 0;
+ for (i = 0; i < cxt.nrealwriters_stress; i++) {
+ cxt.lwsa[i].n_lock_fail = 0;
+ cxt.lwsa[i].n_lock_acquired = 0;
+ }
}
if (cxt.cur_ops->readlock) {
@@ -948,19 +940,21 @@ static int __init lock_torture_init(void)
cxt.nrealreaders_stress = cxt.nrealwriters_stress;
}
- lock_is_read_held = 0;
- cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL);
- if (cxt.lrsa == NULL) {
- VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
- firsterr = -ENOMEM;
- kfree(cxt.lwsa);
- cxt.lwsa = NULL;
- goto unwind;
- }
-
- for (i = 0; i < cxt.nrealreaders_stress; i++) {
- cxt.lrsa[i].n_lock_fail = 0;
- cxt.lrsa[i].n_lock_acquired = 0;
+ if (nreaders_stress) {
+ lock_is_read_held = 0;
+ cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL);
+ if (cxt.lrsa == NULL) {
+ VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
+ firsterr = -ENOMEM;
+ kfree(cxt.lwsa);
+ cxt.lwsa = NULL;
+ goto unwind;
+ }
+
+ for (i = 0; i < cxt.nrealreaders_stress; i++) {
+ cxt.lrsa[i].n_lock_fail = 0;
+ cxt.lrsa[i].n_lock_acquired = 0;
+ }
}
}
@@ -990,12 +984,14 @@ static int __init lock_torture_init(void)
goto unwind;
}
- writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]),
- GFP_KERNEL);
- if (writer_tasks == NULL) {
- VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
- firsterr = -ENOMEM;
- goto unwind;
+ if (nwriters_stress) {
+ writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]),
+ GFP_KERNEL);
+ if (writer_tasks == NULL) {
+ VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
+ firsterr = -ENOMEM;
+ goto unwind;
+ }
}
if (cxt.cur_ops->readlock) {
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 294294c71ba4..38ece035039e 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -170,7 +170,7 @@ static __always_inline void clear_pending_set_locked(struct qspinlock *lock)
* @tail : The new queue tail code word
* Return: The previous queue tail code word
*
- * xchg(lock, tail)
+ * xchg(lock, tail), which heads an address dependency
*
* p,*,* -> n,*,* ; prev = xchg(lock, node)
*/
@@ -409,13 +409,11 @@ queue:
if (old & _Q_TAIL_MASK) {
prev = decode_tail(old);
/*
- * The above xchg_tail() is also a load of @lock which generates,
- * through decode_tail(), a pointer.
- *
- * The address dependency matches the RELEASE of xchg_tail()
- * such that the access to @prev must happen after.
+ * The above xchg_tail() is also a load of @lock which
+ * generates, through decode_tail(), a pointer. The address
+ * dependency matches the RELEASE of xchg_tail() such that
+ * the subsequent access to @prev happens after.
*/
- smp_read_barrier_depends();
WRITE_ONCE(prev->next, node);