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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2006-08-31 15:09:30 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2006-08-31 15:09:30 +0100 |
| commit | 8e34703b9315688305306d26148088b0a8292563 (patch) | |
| tree | 86955dfb894b441525be160e1f6814e6cfbd9a3c | |
| parent | 0355b3e039c621d15321fd0d5cf72d8bdb8f723d (diff) | |
| download | blackbird-op-linux-8e34703b9315688305306d26148088b0a8292563.tar.gz blackbird-op-linux-8e34703b9315688305306d26148088b0a8292563.zip | |
[ARM] Fix ARM __raw_read_trylock() implementation
Matthew Wilcox pointed out that the generic implementation
of this is unfit for use. Here's an ARM optimised version
instead.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | include/asm-arm/spinlock.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/include/asm-arm/spinlock.h b/include/asm-arm/spinlock.h index 406ca97a8ab2..e2f1d75171df 100644 --- a/include/asm-arm/spinlock.h +++ b/include/asm-arm/spinlock.h @@ -199,7 +199,21 @@ static inline void __raw_read_unlock(raw_rwlock_t *rw) : "cc"); } -#define __raw_read_trylock(lock) generic__raw_read_trylock(lock) +static inline int __raw_read_trylock(raw_rwlock_t *rw) +{ + unsigned long tmp tmp2 = 1; + + __asm__ __volatile__( +"1: ldrex %0, [%2]\n" +" adds %0, %0, #1\n" +" strexpl %1, %0, [%2]\n" + : "=&r" (tmp), "+r" (tmp2) + : "r" (&rw->lock) + : "cc"); + + smp_mb(); + return tmp2 == 0; +} /* read_can_lock - would read_trylock() succeed? */ #define __raw_read_can_lock(x) ((x)->lock < 0x80000000) |
