From: Chuck Ebbert <76306.1226@compuserve.com> In spinlock_debug.c, the spinloops call __delay() on every iteration. Because that is an external function, (jiffies_per_loop * HZ), the loop's iteration limit, gets recomputed every time. Caching it explicitly prevents that. Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Cc: Ingo Molnar Signed-off-by: Andrew Morton --- lib/spinlock_debug.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff -puN lib/spinlock_debug.c~spinlock_debug-dont-recompute-jiffies_per_loop lib/spinlock_debug.c --- a/lib/spinlock_debug.c~spinlock_debug-dont-recompute-jiffies_per_loop +++ a/lib/spinlock_debug.c @@ -99,11 +99,12 @@ static inline void debug_spin_unlock(spi static void __spin_lock_debug(spinlock_t *lock) { - int print_once = 1; u64 i; + u64 loops = loops_per_jiffy * HZ; + int print_once = 1; for (;;) { - for (i = 0; i < loops_per_jiffy * HZ; i++) { + for (i = 0; i < loops; i++) { if (__raw_spin_trylock(&lock->raw_lock)) return; __delay(1); @@ -165,11 +166,12 @@ static void rwlock_bug(rwlock_t *lock, c #if 0 /* __write_lock_debug() can lock up - maybe this can too? */ static void __read_lock_debug(rwlock_t *lock) { - int print_once = 1; u64 i; + u64 loops = loops_per_jiffy * HZ; + int print_once = 1; for (;;) { - for (i = 0; i < loops_per_jiffy * HZ; i++) { + for (i = 0; i < loops; i++) { if (__raw_read_trylock(&lock->raw_lock)) return; __delay(1); @@ -239,11 +241,12 @@ static inline void debug_write_unlock(rw #if 0 /* This can cause lockups */ static void __write_lock_debug(rwlock_t *lock) { - int print_once = 1; u64 i; + u64 loops = loops_per_jiffy * HZ; + int print_once = 1; for (;;) { - for (i = 0; i < loops_per_jiffy * HZ; i++) { + for (i = 0; i < loops; i++) { if (__raw_write_trylock(&lock->raw_lock)) return; __delay(1); _