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[PATCH] disable debugging version of write_lock() 

We've confirmed that the debug version of write_lock() can get stuck for long
enough to cause NMI watchdog timeouts and hence a crash.

We don't know why, yet.   Disable it for now.

Also disable the similar read_lock() code.  Just in case.

Thanks to Dave Olson <olson@unixfolk.com> for reporting and testing.

Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andrew Morton 2006-08-05 12:13:47 -07:00 committed by Linus Torvalds
parent 927cbe8a3e
commit 72f0b4e213
1 changed files with 6 additions and 4 deletions
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10
lib/spinlock_debug.c
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@ -162,6 +162,7 @@ static void rwlock_bug(rwlock_t *lock, const char *msg)
#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
#if 0 /* __write_lock_debug() can lock up - maybe this can too? */
static void __read_lock_debug(rwlock_t *lock)
{
int print_once = 1;
@ -184,12 +185,12 @@ static void __read_lock_debug(rwlock_t *lock)
}
}
}
#endif
void _raw_read_lock(rwlock_t *lock)
{
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
if (unlikely(!__raw_read_trylock(&lock->raw_lock)))
__read_lock_debug(lock);
__raw_read_lock(&lock->raw_lock);
}
int _raw_read_trylock(rwlock_t *lock)
@ -235,6 +236,7 @@ static inline void debug_write_unlock(rwlock_t *lock)
lock->owner_cpu = -1;
}
#if 0 /* This can cause lockups */
static void __write_lock_debug(rwlock_t *lock)
{
int print_once = 1;
@ -257,12 +259,12 @@ static void __write_lock_debug(rwlock_t *lock)
}
}
}
#endif
void _raw_write_lock(rwlock_t *lock)
{
debug_write_lock_before(lock);
if (unlikely(!__raw_write_trylock(&lock->raw_lock)))
__write_lock_debug(lock);
__raw_write_lock(&lock->raw_lock);
debug_write_lock_after(lock);
}