commit: http://blackfin.uclinux.org/git/?p=linux-kernel;a=commitdiff;h=d85c852f245947cb376310d81b0d173730106822 branch: http://blackfin.uclinux.org/git/?p=linux-kernel;a=shortlog;h=refs/heads/2011R1
In blackfin SMP architecture, no cache coherence among cores is supppored by hardware. Data protected by spin lock or atomic operation are kept consistent by invalidating entired local cache in spin lock APIs and smp memory barrier APIs on the other cores. In mutex fast path APIs, spin lock may not be called if the lock can be taken by atomic operation. So, smp memory barrier should be invoked to keep cache consistent for SMP architecture without hardware cache coherency support. Signed-off-by: Sonic Zhang <[email protected]> --- include/asm-generic/mutex-dec.h | 10 +++++++++- include/asm-generic/mutex-xchg.h | 8 ++++++++ 2 files changed, 17 insertions(+), 1 deletions(-) diff --git a/include/asm-generic/mutex-dec.h b/include/asm-generic/mutex-dec.h index f104af7..61f722f 100644 --- a/include/asm-generic/mutex-dec.h +++ b/include/asm-generic/mutex-dec.h @@ -22,6 +22,8 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) { if (unlikely(atomic_dec_return(count) < 0)) fail_fn(count); + else + smp_rmb(); } /** @@ -39,6 +41,8 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) { if (unlikely(atomic_dec_return(count) < 0)) return fail_fn(count); + else + smp_rmb(); return 0; } @@ -60,6 +64,8 @@ __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) { if (unlikely(atomic_inc_return(count) <= 0)) fail_fn(count); + else + smp_wmb(); } #define __mutex_slowpath_needs_to_unlock() 1 @@ -82,8 +88,10 @@ __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) static inline int __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) { - if (likely(atomic_cmpxchg(count, 1, 0) == 1)) + if (likely(atomic_cmpxchg(count, 1, 0) == 1)) { + smp_rmb(); return 1; + } return 0; } diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h index 580a6d3..6d6bde8 100644 --- a/include/asm-generic/mutex-xchg.h +++ b/include/asm-generic/mutex-xchg.h @@ -27,6 +27,8 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) { if (unlikely(atomic_xchg(count, 0) != 1)) fail_fn(count); + else + smp_rmb(); } /** @@ -44,6 +46,8 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) { if (unlikely(atomic_xchg(count, 0) != 1)) return fail_fn(count); + else + smp_rmb(); return 0; } @@ -64,6 +68,8 @@ __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) { if (unlikely(atomic_xchg(count, 1) != 0)) fail_fn(count); + else + smp_wmb(); } #define __mutex_slowpath_needs_to_unlock() 0 @@ -104,6 +110,8 @@ __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) if (prev < 0) prev = 0; } + if (prev) + smp_rmb(); return prev; }
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