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Commit cb490d63 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 6a810945 8a5fd564

kernel/locking/lockdep.c

+10 −6
Original line number Diff line number Diff line
@@ -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))

	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: