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author | Nick Piggin <npiggin@suse.de> | 2006-02-20 10:41:40 +0100 |
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committer | Paul Mackerras <paulus@samba.org> | 2006-02-24 14:06:02 +1100 |
commit | f055affb89f587a03f3411c3fd49ef31295c3d48 (patch) | |
tree | 1c40a29191eba8267390fe397f8108ffa8d9ddb5 /include/asm-powerpc/atomic.h | |
parent | 4f629d7db32decbadaab2abfa4d021fee94990ef (diff) | |
download | lwn-f055affb89f587a03f3411c3fd49ef31295c3d48.tar.gz lwn-f055affb89f587a03f3411c3fd49ef31295c3d48.zip |
[PATCH] powerpc: native atomic_add_unless
Do atomic_add_unless natively instead of using cmpxchg.
Improved register allocation idea from Joel Schopp.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'include/asm-powerpc/atomic.h')
-rw-r--r-- | include/asm-powerpc/atomic.h | 38 |
1 files changed, 24 insertions, 14 deletions
diff --git a/include/asm-powerpc/atomic.h b/include/asm-powerpc/atomic.h index 147a38dcc766..bb3c0ab7e667 100644 --- a/include/asm-powerpc/atomic.h +++ b/include/asm-powerpc/atomic.h @@ -8,6 +8,7 @@ typedef struct { volatile int counter; } atomic_t; #ifdef __KERNEL__ +#include <linux/compiler.h> #include <asm/synch.h> #include <asm/asm-compat.h> @@ -176,20 +177,29 @@ static __inline__ int atomic_dec_return(atomic_t *v) * Atomically adds @a to @v, so long as it was not @u. * Returns non-zero if @v was not @u, and zero otherwise. */ -#define atomic_add_unless(v, a, u) \ -({ \ - int c, old; \ - c = atomic_read(v); \ - for (;;) { \ - if (unlikely(c == (u))) \ - break; \ - old = atomic_cmpxchg((v), c, c + (a)); \ - if (likely(old == c)) \ - break; \ - c = old; \ - } \ - c != (u); \ -}) +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int t; + + __asm__ __volatile__ ( + LWSYNC_ON_SMP +"1: lwarx %0,0,%1 # atomic_add_unless\n\ + cmpw 0,%0,%3 \n\ + beq- 2f \n\ + add %0,%2,%0 \n" + PPC405_ERR77(0,%2) +" stwcx. %0,0,%1 \n\ + bne- 1b \n" + ISYNC_ON_SMP +" subf %0,%2,%0 \n\ +2:" + : "=&r" (t) + : "r" (&v->counter), "r" (a), "r" (u) + : "cc", "memory"); + + return t != u; +} + #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) #define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0) |