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| author | Paul Burton <paul.burton@imgtec.com> | 2017-06-09 17:26:39 -0700 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-06-29 02:42:25 +0200 |
| commit | b70eb30056dc84568f3d32440d9be6a558025843 (patch) | |
| tree | 2e0ab36189d3eb6dbf5bbb995b9aa7bf896a6e0f /arch/mips/include | |
| parent | 8263db4d7768448cb06adbbdd14c613a1ea09830 (diff) | |
| download | linux-b70eb30056dc84568f3d32440d9be6a558025843.tar.gz linux-b70eb30056dc84568f3d32440d9be6a558025843.tar.bz2 linux-b70eb30056dc84568f3d32440d9be6a558025843.zip | |
MIPS: cmpxchg: Implement 1 byte & 2 byte xchg()
Implement 1 & 2 byte xchg() using read-modify-write atop a 4 byte
cmpxchg(). This allows us to support these atomic operations despite the
MIPS ISA only providing for 4 & 8 byte atomic operations.
This is required in order to support queued spinlocks (qspinlock) in a
later patch, since these make use of a 2 byte xchg() in their slow path.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16354/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include')
| -rw-r--r-- | arch/mips/include/asm/cmpxchg.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h index 516cb66f066b..a633bf845689 100644 --- a/arch/mips/include/asm/cmpxchg.h +++ b/arch/mips/include/asm/cmpxchg.h @@ -70,9 +70,16 @@ extern unsigned long __xchg_called_with_bad_pointer(void) __ret; \ }) +extern unsigned long __xchg_small(volatile void *ptr, unsigned long val, + unsigned int size); + static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size) { switch (size) { + case 1: + case 2: + return __xchg_small(ptr, x, size); + case 4: return __xchg_asm("ll", "sc", (volatile u32 *)ptr, x); @@ -91,8 +98,6 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz ({ \ __typeof__(*(ptr)) __res; \ \ - BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc); \ - \ smp_mb__before_llsc(); \ \ __res = (__typeof__(*(ptr))) \ |