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Commit c22f008b authored by Chuck Ebbert's avatar Chuck Ebbert Committed by Linus Torvalds
Browse files

[PATCH] spinlock_debug: don't recompute (jiffies_per_loop * HZ) in spinloop 



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: default avatarChuck Ebbert <76306.1226@compuserve.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 92a0f861

lib/spinlock_debug.c

+9 −6
Original line number Diff line number Diff line
@@ -99,11 +99,12 @@ static inline void debug_spin_unlock(spinlock_t *lock) 


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, const char *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;

	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(rwlock_t *lock) 
#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);