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authorByungchul Park <byungchul.park@lge.com>2017-08-07 16:12:51 +0900
committerIngo Molnar <mingo@kernel.org>2017-08-10 12:29:06 +0200
commitce07a9415f266e181a0a33033a5f7138760240a4 (patch)
tree29cb6ed4f40bd89847c0884c2178766704a68fdc /kernel/locking
parent70911fdc9576f4eeb3986689a1c9a778a4a4aacb (diff)
downloadlinux-ce07a9415f266e181a0a33033a5f7138760240a4.tar.bz2
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: 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>
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/lockdep.c40
1 files changed, 19 insertions, 21 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 7cf02fab1725..841828ba35b9 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -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))
- return 0;
- *stack_saved = 1;
- }
+ if (save && !save(trace))
+ return 0;
/*
* 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