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

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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: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Byungchul Park 2017-08-07 16:12:51 +09:00 committed by Ingo Molnar
parent 70911fdc95
commit ce07a9415f
1 changed files with 19 additions and 21 deletions
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38
kernel/locking/lockdep.c
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@ -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