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MIPS: cmpxchg: Drop __xchg_u{32,64} functions

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The __xchg_u32() & __xchg_u64() functions now add very little value.
This patch therefore removes them, by:

  - Moving memory barriers out of them & into xchg(), which also removes
    the duplication & readies us to support xchg_relaxed() if we wish to.

  - Calling __xchg_asm() directly from __xchg().

  - Performing the check for CONFIG_64BIT being enabled in the size=8
    case of __xchg().

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16352/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2017-06-09 17:26:37 -07:00 committed by Ralf Baechle
parent d15dc68c11
commit 62c6081dca
1 changed files with 17 additions and 31 deletions
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48
arch/mips/include/asm/cmpxchg.h
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@ -70,40 +70,18 @@ extern unsigned long __xchg_called_with_bad_pointer(void)
__ret; \
})
static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
{
__u32 retval;
smp_mb__before_llsc();
retval = __xchg_asm("ll", "sc", m, val);
smp_llsc_mb();
return retval;
}
#ifdef CONFIG_64BIT
static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
{
__u64 retval;
smp_mb__before_llsc();
retval = __xchg_asm("lld", "scd", m, val);
smp_llsc_mb();
return retval;
}
#else
extern __u64 __xchg_u64_unsupported_on_32bit_kernels(volatile __u64 * m, __u64 val);
#define __xchg_u64 __xchg_u64_unsupported_on_32bit_kernels
#endif
static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
{
switch (size) {
case 4:
return __xchg_u32(ptr, x);
return __xchg_asm("ll", "sc", (volatile u32 *)ptr, x);
case 8:
return __xchg_u64(ptr, x);
if (!IS_ENABLED(CONFIG_64BIT))
return __xchg_called_with_bad_pointer();
return __xchg_asm("lld", "scd", (volatile u64 *)ptr, x);
default:
return __xchg_called_with_bad_pointer();
}
@ -111,10 +89,18 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
#define xchg(ptr, x) \
({ \
__typeof__(*(ptr)) __res; \
\
BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc); \
\
((__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
smp_mb__before_llsc(); \
\
__res = (__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))); \
\
smp_llsc_mb(); \
\
__res; \
})
#define __cmpxchg_asm(ld, st, m, old, new) \