summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorVineet Gupta <vgupta@synopsys.com>2015-07-21 18:46:53 +0300
committerVineet Gupta <vgupta@synopsys.com>2015-08-04 09:26:35 +0530
commitb89aa12c177477e34caa722818536fb5d0bffd76 (patch)
tree66f2d999f9f0a140790fc62f50504e2ce659bd01
parente78fdfef84be13a5c2b8276e12203cdf24778596 (diff)
ARCv2: spinlock/rwlock: Reset retry delay when starting a new spin-wait cycle
The previous commit for delayed retry of SCOND needs some fine tuning for spin locks. The backoff from delayed retry in conjunction with spin looping of lock itself can potentially cause the delay counter to reach high values. So to provide fairness to any lock operation, after a lock "seems" available (i.e. just before first SCOND try0, reset the delay counter back to starting value of 1 Essentially reset delay to 1 for a new spin-wait-loop-acquire cycle. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
-rw-r--r--arch/arc/include/asm/spinlock.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
index 2a84525b5aa4..7071fc0da56a 100644
--- a/arch/arc/include/asm/spinlock.h
+++ b/arch/arc/include/asm/spinlock.h
@@ -279,7 +279,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[slock]] \n"
- " breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */
+ " breq %[val], %[LOCKED], 0b \n" /* spin while LOCKED */
" scond %[LOCKED], [%[slock]] \n" /* acquire */
" bz 4f \n" /* done */
" \n"
@@ -358,7 +358,7 @@ static inline void arch_read_lock(arch_rwlock_t *rw)
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
- " brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */
+ " brls %[val], %[WR_LOCKED], 0b\n" /* <= 0: spin while write locked */
" sub %[val], %[val], 1 \n" /* reader lock */
" scond %[val], [%[rwlock]] \n"
" bz 4f \n" /* done */
@@ -427,7 +427,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
__asm__ __volatile__(
"0: mov %[delay], 1 \n"
"1: llock %[val], [%[rwlock]] \n"
- " brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */
+ " brne %[val], %[UNLOCKED], 0b \n" /* while !UNLOCKED spin */
" mov %[val], %[WR_LOCKED] \n"
" scond %[val], [%[rwlock]] \n"
" bz 4f \n"