diff options
| author | Andreas Larsson <andreas@gaisler.com> | 2014-11-05 15:52:08 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-21 09:22:52 -0800 |
| commit | 96920746658f98dbdaccc90ab818443471accc89 (patch) | |
| tree | 90c3956ca5c0d736056e45ae5fa1b9136edb8459 /arch | |
| parent | 134712463afbd65c6b11193cd8000c83fc5b3a1b (diff) | |
sparc32: Implement xchg and atomic_xchg using ATOMIC_HASH locks
[ Upstream commit 1a17fdc4f4ed06b63fac1937470378a5441a663a ]
Atomicity between xchg and cmpxchg cannot be guaranteed when xchg is
implemented with a swap and cmpxchg is implemented with locks.
Without this, e.g. mcs_spin_lock and mcs_spin_unlock are broken.
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/sparc/include/asm/atomic_32.h | 2 | ||||
| -rw-r--r-- | arch/sparc/include/asm/cmpxchg_32.h | 12 | ||||
| -rw-r--r-- | arch/sparc/lib/atomic32.c | 27 |
3 files changed, 30 insertions, 11 deletions
diff --git a/arch/sparc/include/asm/atomic_32.h b/arch/sparc/include/asm/atomic_32.h index 905832aa9e9e..a0ed182ae73c 100644 --- a/arch/sparc/include/asm/atomic_32.h +++ b/arch/sparc/include/asm/atomic_32.h @@ -21,7 +21,7 @@ extern int __atomic_add_return(int, atomic_t *); extern int atomic_cmpxchg(atomic_t *, int, int); -#define atomic_xchg(v, new) (xchg(&((v)->counter), new)) +extern int atomic_xchg(atomic_t *, int); extern int __atomic_add_unless(atomic_t *, int, int); extern void atomic_set(atomic_t *, int); diff --git a/arch/sparc/include/asm/cmpxchg_32.h b/arch/sparc/include/asm/cmpxchg_32.h index 1fae1a02e3c2..ae0f9a7a314d 100644 --- a/arch/sparc/include/asm/cmpxchg_32.h +++ b/arch/sparc/include/asm/cmpxchg_32.h @@ -11,22 +11,14 @@ #ifndef __ARCH_SPARC_CMPXCHG__ #define __ARCH_SPARC_CMPXCHG__ -static inline unsigned long xchg_u32(__volatile__ unsigned long *m, unsigned long val) -{ - __asm__ __volatile__("swap [%2], %0" - : "=&r" (val) - : "0" (val), "r" (m) - : "memory"); - return val; -} - +extern unsigned long __xchg_u32(volatile u32 *m, u32 new); extern void __xchg_called_with_bad_pointer(void); static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size) { switch (size) { case 4: - return xchg_u32(ptr, x); + return __xchg_u32(ptr, x); } __xchg_called_with_bad_pointer(); return x; diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c index 1d32b54089aa..8f2f94d53434 100644 --- a/arch/sparc/lib/atomic32.c +++ b/arch/sparc/lib/atomic32.c @@ -40,6 +40,19 @@ int __atomic_add_return(int i, atomic_t *v) } EXPORT_SYMBOL(__atomic_add_return); +int atomic_xchg(atomic_t *v, int new) +{ + int ret; + unsigned long flags; + + spin_lock_irqsave(ATOMIC_HASH(v), flags); + ret = v->counter; + v->counter = new; + spin_unlock_irqrestore(ATOMIC_HASH(v), flags); + return ret; +} +EXPORT_SYMBOL(atomic_xchg); + int atomic_cmpxchg(atomic_t *v, int old, int new) { int ret; @@ -132,3 +145,17 @@ unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new) return (unsigned long)prev; } EXPORT_SYMBOL(__cmpxchg_u32); + +unsigned long __xchg_u32(volatile u32 *ptr, u32 new) +{ + unsigned long flags; + u32 prev; + + spin_lock_irqsave(ATOMIC_HASH(ptr), flags); + prev = *ptr; + *ptr = new; + spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags); + + return (unsigned long)prev; +} +EXPORT_SYMBOL(__xchg_u32); |