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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-02-14 12:02:05 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-02-14 12:02:05 -0800 |
| commit | cb490d632b9c7a3f08a9c73b88956132b6ad299c (patch) | |
| tree | 33de4871fe6ecbd3f5ed6084169484ff0a1b81be | |
| parent | 6a810945ed23554aa71634ff0bf976da41de9045 (diff) | |
| parent | 8a5fd56431fe1682e870bd6ab0c276e74befbeb9 (diff) | |
| download | linux-cb490d632b9c7a3f08a9c73b88956132b6ad299c.tar.bz2 | |
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.c | 16 |
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: |