[RFC v2 03/13] lockdep: Make check_prev_add can use a stack_trace of other context
From: Byungchul Park <hidden>
Date: 2016-07-07 09:32:00
Also in:
lkml
Subsystem:
locking primitives, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Linus Torvalds
Currently, check_prev_add() can only save its current context's stack trace. But it would be useful if a seperated stack_trace can be taken and used in check_prev_add(). Crossrelease feature can use check_prev_add() with another context's stack_trace. Signed-off-by: Byungchul Park <redacted> --- kernel/locking/lockdep.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4d51208..c596bef 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c@@ -1822,7 +1822,8 @@ 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, int *stack_saved, + struct stack_trace *own_trace) { struct lock_list *entry; int ret;
@@ -1883,7 +1884,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, } } - if (!*stack_saved) { + if (!own_trace && stack_saved && !*stack_saved) { if (!save_trace(&trace)) return 0; *stack_saved = 1;
@@ -1895,14 +1896,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, */ ret = add_lock_to_list(hlock_class(prev), hlock_class(next), &hlock_class(prev)->locks_after, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, own_trace ?: &trace); if (!ret) return 0; ret = add_lock_to_list(hlock_class(next), hlock_class(prev), &hlock_class(next)->locks_before, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, own_trace ?: &trace); if (!ret) return 0;
@@ -1911,7 +1912,8 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, */ if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { /* We drop graph lock, so another thread can overwrite trace. */ - *stack_saved = 0; + if (stack_saved) + *stack_saved = 0; graph_unlock(); printk("\n new dependency: "); print_lock_name(hlock_class(prev));
@@ -1960,8 +1962,8 @@ 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)) + if (!check_prev_add(curr, hlock, next, distance, + &stack_saved, NULL)) return 0; /* * Stop after the first non-trylock entry,
--
1.9.1
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