Commit ce07a941 authored by Byungchul Park's avatar Byungchul Park Committed by Ingo Molnar
Browse files

locking/lockdep: Make check_prev_add() able to handle external stack_trace 



Currently, a space for stack_trace is pinned in check_prev_add(), that
makes us not able to use external stack_trace. The simplest way to
achieve it is to pass an external stack_trace as an argument.

A more suitable solution is to pass a callback additionally along with
a stack_trace so that callers can decide the way to save or whether to
save. Actually crossrelease needs to do other than saving a stack_trace.
So pass a stack_trace and callback to handle it, to check_prev_add().

Signed-off-by: default avatarByungchul Park <byungchul.park@lge.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-5-git-send-email-byungchul.park@lge.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 70911fdc

kernel/locking/lockdep.c

+19 −21
Original line number Diff line number Diff line
@@ -1824,20 +1824,13 @@ 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 *stack_saved)

	       struct held_lock *next, int distance, struct stack_trace *trace,

	       int (*save)(struct stack_trace *trace))

{

	struct lock_list *entry;

	int ret;

	struct lock_list this;

	struct lock_list *uninitialized_var(target_entry);

	/*

	 * Static variable, serialized by the graph_lock().

	 *

	 * We use this static variable to save the stack trace in case

	 * we call into this function multiple times due to encountering

	 * trylocks in the held lock stack.

	 */

	static struct stack_trace trace;



	/*

	 * Prove that the new <prev> -> <next> dependency would not
@@ -1899,11 +1892,8 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
		return print_bfs_bug(ret);





	if (!*stack_saved) {

		if (!save_trace(&trace))

	if (save && !save(trace))

		return 0;

		*stack_saved = 1;

	}



	/*

	 * Ok, all validations passed, add the new lock
@@ -1911,14 +1901,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
	 */

	ret = add_lock_to_list(hlock_class(next),

			       &hlock_class(prev)->locks_after,

			       next->acquire_ip, distance, &trace);

			       next->acquire_ip, distance, trace);



	if (!ret)

		return 0;



	ret = add_lock_to_list(hlock_class(prev),

			       &hlock_class(next)->locks_before,

			       next->acquire_ip, distance, &trace);

			       next->acquire_ip, distance, trace);

	if (!ret)

		return 0;
@@ -1926,8 +1916,6 @@ 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));
@@ -1951,8 +1939,9 @@ static int 
check_prevs_add(struct task_struct *curr, struct held_lock *next)

{

	int depth = curr->lockdep_depth;

	int stack_saved = 0;

	struct held_lock *hlock;

	struct stack_trace trace;

	int (*save)(struct stack_trace *trace) = save_trace;



	/*

	 * Debugging checks.
@@ -1977,9 +1966,18 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) 
		 * added:

		 */

		if (hlock->read != 2 && hlock->check) {

			if (!check_prev_add(curr, hlock, next,

						distance, &stack_saved))

			int ret = check_prev_add(curr, hlock, next,

						distance, &trace, save);

			if (!ret)

				return 0;



			/*

			 * Stop saving stack_trace if save_trace() was

			 * called at least once:

			 */

			if (save && ret == 2)

				save = NULL;



			/*

			 * Stop after the first non-trylock entry,

			 * as non-trylock entries have added their

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