diff options
author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-08-13 15:39:10 -0400 |
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committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-08-13 15:39:10 -0400 |
commit | 0980bd9cd32de2fef7eaa2858345c49d14498625 (patch) | |
tree | 41f5f823d0569a81b22037e79c22d823933a63f1 /arch/arm/include/asm/mutex.h | |
parent | 78821b2c0299ab807d483802f09897728b93bce0 (diff) | |
parent | 0d7614f09c1ebdbaa1599a5aba7593f147bf96ee (diff) |
Merge commit 'v3.6-rc1' into linux-next
* commit 'v3.6-rc1': (9532 commits)
Linux 3.6-rc1
mm: remove node_start_pfn checking in new WARN_ON for now
ARM: mmp: add missing irqs.h
arm: mvebu: fix typo in .dtsi comment for Armada XP SoCs
ARM: PRIMA2: delete redundant codes to restore LATCHED when timer resumes
libceph: fix crypto key null deref, memory leak
ceph: simplify+fix atomic_open
sh: explicitly include sh_dma.h in setup-sh7722.c
um: Add arch/x86/um to MAINTAINERS
um: pass siginfo to guest process
um: fix ubd_file_size for read-only files
md/dm-raid: DM_RAID should select MD_RAID10
md/raid1: submit IO from originating thread instead of md thread.
raid5: raid5d handle stripe in batch way
raid5: make_request use batch stripe release
um: pull interrupt_end() into userspace()
um: split syscall_trace(), pass pt_regs to it
um: switch UPT_SET_RETURN_VALUE and regs_return_value to pt_regs
MIPS: Loongson 2: Sort out clock managment.
locks: remove unused lm_release_private
...
Diffstat (limited to 'arch/arm/include/asm/mutex.h')
-rw-r--r-- | arch/arm/include/asm/mutex.h | 119 |
1 files changed, 4 insertions, 115 deletions
diff --git a/arch/arm/include/asm/mutex.h b/arch/arm/include/asm/mutex.h index 93226cf23ae0..b1479fd04a95 100644 --- a/arch/arm/include/asm/mutex.h +++ b/arch/arm/include/asm/mutex.h @@ -7,121 +7,10 @@ */ #ifndef _ASM_MUTEX_H #define _ASM_MUTEX_H - -#if __LINUX_ARM_ARCH__ < 6 -/* On pre-ARMv6 hardware the swp based implementation is the most efficient. */ -# include <asm-generic/mutex-xchg.h> -#else - /* - * Attempting to lock a mutex on ARMv6+ can be done with a bastardized - * atomic decrement (it is not a reliable atomic decrement but it satisfies - * the defined semantics for our purpose, while being smaller and faster - * than a real atomic decrement or atomic swap. The idea is to attempt - * decrementing the lock value only once. If once decremented it isn't zero, - * or if its store-back fails due to a dispute on the exclusive store, we - * simply bail out immediately through the slow path where the lock will be - * reattempted until it succeeds. + * On pre-ARMv6 hardware this results in a swp-based implementation, + * which is the most efficient. For ARMv6+, we emit a pair of exclusive + * accesses instead. */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - int __ex_flag, __res; - - __asm__ ( - - "ldrex %0, [%2] \n\t" - "sub %0, %0, #1 \n\t" - "strex %1, %0, [%2] " - - : "=&r" (__res), "=&r" (__ex_flag) - : "r" (&(count)->counter) - : "cc","memory" ); - - __res |= __ex_flag; - if (unlikely(__res != 0)) - fail_fn(count); -} - -static inline int -__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - int __ex_flag, __res; - - __asm__ ( - - "ldrex %0, [%2] \n\t" - "sub %0, %0, #1 \n\t" - "strex %1, %0, [%2] " - - : "=&r" (__res), "=&r" (__ex_flag) - : "r" (&(count)->counter) - : "cc","memory" ); - - __res |= __ex_flag; - if (unlikely(__res != 0)) - __res = fail_fn(count); - return __res; -} - -/* - * Same trick is used for the unlock fast path. However the original value, - * rather than the result, is used to test for success in order to have - * better generated assembly. - */ -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - int __ex_flag, __res, __orig; - - __asm__ ( - - "ldrex %0, [%3] \n\t" - "add %1, %0, #1 \n\t" - "strex %2, %1, [%3] " - - : "=&r" (__orig), "=&r" (__res), "=&r" (__ex_flag) - : "r" (&(count)->counter) - : "cc","memory" ); - - __orig |= __ex_flag; - if (unlikely(__orig != 0)) - fail_fn(count); -} - -/* - * If the unlock was done on a contended lock, or if the unlock simply fails - * then the mutex remains locked. - */ -#define __mutex_slowpath_needs_to_unlock() 1 - -/* - * For __mutex_fastpath_trylock we use another construct which could be - * described as a "single value cmpxchg". - * - * This provides the needed trylock semantics like cmpxchg would, but it is - * lighter and less generic than a true cmpxchg implementation. - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - int __ex_flag, __res, __orig; - - __asm__ ( - - "1: ldrex %0, [%3] \n\t" - "subs %1, %0, #1 \n\t" - "strexeq %2, %1, [%3] \n\t" - "movlt %0, #0 \n\t" - "cmpeq %2, #0 \n\t" - "bgt 1b " - - : "=&r" (__orig), "=&r" (__res), "=&r" (__ex_flag) - : "r" (&count->counter) - : "cc", "memory" ); - - return __orig; -} - -#endif +#include <asm-generic/mutex-xchg.h> #endif |