[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>
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index c8bb8cc..d8b6bb4 100644
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -72,9 +72,9 @@
for (;;) {
for (i = 0; i < loops_per_jiffy * HZ; i++) {
- cpu_relax();
if (__raw_spin_trylock(&lock->raw_lock))
return;
+ __delay(1);
}
/* lockup suspected: */
if (print_once) {
@@ -144,9 +144,9 @@
for (;;) {
for (i = 0; i < loops_per_jiffy * HZ; i++) {
- cpu_relax();
if (__raw_read_trylock(&lock->raw_lock))
return;
+ __delay(1);
}
/* lockup suspected: */
if (print_once) {
@@ -217,9 +217,9 @@
for (;;) {
for (i = 0; i < loops_per_jiffy * HZ; i++) {
- cpu_relax();
if (__raw_write_trylock(&lock->raw_lock))
return;
+ __delay(1);
}
/* lockup suspected: */
if (print_once) {
