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locking/lockdep: Apply crossrelease to completions 

Although wait_for_completion() and its family can cause deadlock, the
lock correctness validator could not be applied to them until now,
because things like complete() are usually called in a different context
from the waiting context, which violates lockdep's assumption.

Thanks to CONFIG_LOCKDEP_CROSSRELEASE, we can now apply the lockdep
detector to those completion operations. Applied it.

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/1502089981-21272-10-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 16:12:56 +09:00 committed by Ingo Molnar
parent 383a4bc888
commit cd8084f91c
3 changed files with 64 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
include/linux/completion.h
View File

@ -9,6 +9,9 @@
*/
#include <linux/wait.h>
#ifdef CONFIG_LOCKDEP_COMPLETE
#include <linux/lockdep.h>
#endif
/*
* struct completion - structure used to maintain state for a "completion"
@ -25,10 +28,50 @@
struct completion {
unsigned int done;
wait_queue_head_t wait;
#ifdef CONFIG_LOCKDEP_COMPLETE
struct lockdep_map_cross map;
#endif
};
#ifdef CONFIG_LOCKDEP_COMPLETE
static inline void complete_acquire(struct completion *x)
{
lock_acquire_exclusive((struct lockdep_map *)&x->map, 0, 0, NULL, _RET_IP_);
}
static inline void complete_release(struct completion *x)
{
lock_release((struct lockdep_map *)&x->map, 0, _RET_IP_);
}
static inline void complete_release_commit(struct completion *x)
{
lock_commit_crosslock((struct lockdep_map *)&x->map);
}
#define init_completion(x) \
do { \
static struct lock_class_key __key; \
lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \
"(complete)" #x, \
&__key, 0); \
__init_completion(x); \
} while (0)
#else
#define init_completion(x) __init_completion(x)
static inline void complete_acquire(struct completion *x) {}
static inline void complete_release(struct completion *x) {}
static inline void complete_release_commit(struct completion *x) {}
#endif
#ifdef CONFIG_LOCKDEP_COMPLETE
#define COMPLETION_INITIALIZER(work) \
{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait), \
STATIC_CROSS_LOCKDEP_MAP_INIT("(complete)" #work, &(work)) }
#else
#define COMPLETION_INITIALIZER(work) \
{ 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
#endif
#define COMPLETION_INITIALIZER_ONSTACK(work) \
({ init_completion(&work); work; })
@ -70,7 +113,7 @@ struct completion {
* This inline function will initialize a dynamically created completion
* structure.
*/
static inline void init_completion(struct completion *x)
static inline void __init_completion(struct completion *x)
{
x->done = 0;
init_waitqueue_head(&x->wait);

11
kernel/sched/completion.c
View File

@ -32,6 +32,12 @@ void complete(struct completion *x)
unsigned long flags;
spin_lock_irqsave(&x->wait.lock, flags);
/*
* Perform commit of crossrelease here.
*/
complete_release_commit(x);
if (x->done != UINT_MAX)
x->done++;
__wake_up_locked(&x->wait, TASK_NORMAL, 1);
@ -92,9 +98,14 @@ __wait_for_common(struct completion *x,
{
might_sleep();
complete_acquire(x);
spin_lock_irq(&x->wait.lock);
timeout = do_wait_for_common(x, action, timeout, state);
spin_unlock_irq(&x->wait.lock);
complete_release(x);
return timeout;
}

9
lib/Kconfig.debug
View File

@ -1162,6 +1162,15 @@ config LOCKDEP_CROSSRELEASE
such as page locks or completions can use the lock correctness
detector, lockdep.
config LOCKDEP_COMPLETE
bool "Lock debugging: allow completions to use deadlock detector"
depends on PROVE_LOCKING
select LOCKDEP_CROSSRELEASE
default n
help
A deadlock caused by wait_for_completion() and complete() can be
detected by lockdep using crossrelease feature.
config DEBUG_LOCKDEP
bool "Lock dependency engine debugging"
depends on DEBUG_KERNEL && LOCKDEP