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authorLinus Torvalds <torvalds@linux-foundation.org>2016-02-14 12:02:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-14 12:02:05 -0800
commitcb490d632b9c7a3f08a9c73b88956132b6ad299c (patch)
tree33de4871fe6ecbd3f5ed6084169484ff0a1b81be
parent6a810945ed23554aa71634ff0bf976da41de9045 (diff)
parent8a5fd56431fe1682e870bd6ab0c276e74befbeb9 (diff)
downloadlinux-sh-cb490d632b9c7a3f08a9c73b88956132b6ad299c.tar.gz
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull lockdep fix from Thomas Gleixner: "A single fix for the stack trace caching logic in lockdep, where the duplicate avoidance managed to store no back trace at all" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/lockdep: Fix stack trace caching logic
-rw-r--r--kernel/locking/lockdep.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 7537e568dabe..716547fdb873 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1822,7 +1822,7 @@ check_deadlock(struct task_struct *curr, struct held_lock *next,
*/
static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, int distance, int trylock_loop)
+ struct held_lock *next, int distance, int *stack_saved)
{
struct lock_list *entry;
int ret;
@@ -1883,8 +1883,11 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
}
}
- if (!trylock_loop && !save_trace(&trace))
- return 0;
+ if (!*stack_saved) {
+ if (!save_trace(&trace))
+ return 0;
+ *stack_saved = 1;
+ }
/*
* Ok, all validations passed, add the new lock
@@ -1907,6 +1910,8 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
* Debugging printouts:
*/
if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
+ /* We drop graph lock, so another thread can overwrite trace. */
+ *stack_saved = 0;
graph_unlock();
printk("\n new dependency: ");
print_lock_name(hlock_class(prev));
@@ -1929,7 +1934,7 @@ static int
check_prevs_add(struct task_struct *curr, struct held_lock *next)
{
int depth = curr->lockdep_depth;
- int trylock_loop = 0;
+ int stack_saved = 0;
struct held_lock *hlock;
/*
@@ -1956,7 +1961,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
*/
if (hlock->read != 2 && hlock->check) {
if (!check_prev_add(curr, hlock, next,
- distance, trylock_loop))
+ distance, &stack_saved))
return 0;
/*
* Stop after the first non-trylock entry,
@@ -1979,7 +1984,6 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
if (curr->held_locks[depth].irq_context !=
curr->held_locks[depth-1].irq_context)
break;
- trylock_loop = 1;
}
return 1;
out_bug: