[PATCH] Fix spinlock debugging delays to not time out too early
The spinlock-debug wait-loop was using loops_per_jiffy to detect too long spinlock waits - but on fast CPUs this led to a way too fast timeout and false messages. The fix is to include a __delay(1) call in the loop, to correctly approximate the intended delay timeout of 1 second. The code assumes that every architecture implements __delay(1) to last around 1/(loops_per_jiffy*HZ) seconds. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -72,9 +72,9 @@ static void __spin_lock_debug(spinlock_t *lock)
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_spin_trylock(&lock->raw_lock))
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return;
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__delay(1);
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}
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/* lockup suspected: */
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if (print_once) {
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@ -144,9 +144,9 @@ static void __read_lock_debug(rwlock_t *lock)
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_read_trylock(&lock->raw_lock))
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return;
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__delay(1);
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}
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/* lockup suspected: */
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if (print_once) {
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@ -217,9 +217,9 @@ static void __write_lock_debug(rwlock_t *lock)
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_write_trylock(&lock->raw_lock))
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return;
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__delay(1);
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}
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/* lockup suspected: */
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if (print_once) {
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