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authorWill Deacon <will.deacon@arm.com>2013-01-24 14:47:38 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-01-28 14:13:05 +0000
commit20e260b6f4f717c100620122f626a2c06a4cfd72 (patch)
treeb2f0c8c70f86ae41f742604b4eb6c08d75109595 /arch/arm/include/asm/spinlock.h
parent0a301110b7bd33ef10164c184fe2c1d8c4c3ab6b (diff)
downloadlinux-20e260b6f4f717c100620122f626a2c06a4cfd72.tar.gz
ARM: 7632/1: spinlock: avoid exclusive accesses on unlock() path
When unlocking a spinlock, all we need to do is increment the owner field of the lock. Since only one CPU can be performing an unlock() operation for a given lock, this doesn't need to be exclusive. This patch simplifies arch_spin_unlock to use non-exclusive accesses when updating the owner field of the lock. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/spinlock.h')
-rw-r--r--arch/arm/include/asm/spinlock.h16
1 files changed, 1 insertions, 15 deletions
diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index b4ca707d0a6..6220e9fdf4c 100644
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -119,22 +119,8 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
- unsigned long tmp;
- u32 slock;
-
smp_mb();
-
- __asm__ __volatile__(
-" mov %1, #1\n"
-"1: ldrex %0, [%2]\n"
-" uadd16 %0, %0, %1\n"
-" strex %1, %0, [%2]\n"
-" teq %1, #0\n"
-" bne 1b"
- : "=&r" (slock), "=&r" (tmp)
- : "r" (&lock->slock)
- : "cc");
-
+ lock->tickets.owner++;
dsb_sev();
}