* TODO: implement optimized primitives instead, or leave the generic
* implementation in place, or pick the atomic_xchg() based generic
* implementation. (see asm-generic/mutex-xchg.h for details)
+ *
+ * Copyright 2006-2009 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
*/
-#include <asm-generic/mutex-dec.h>
+#ifndef _ASM_MUTEX_H
+#define _ASM_MUTEX_H
+
+#ifndef CONFIG_SMP
+#include <asm-generic/mutex.h>
+#else
+
+static inline void
+__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
+{
+ if (unlikely(atomic_dec_return(count) < 0))
+ fail_fn(count);
+ else
+ smp_mb();
+}
+
+static inline int
+__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_mb();
+ return 0;
+ }
+}
+
+static inline void
+__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
+{
+ smp_mb();
+ if (unlikely(atomic_inc_return(count) <= 0))
+ fail_fn(count);
+}
+
+#define __mutex_slowpath_needs_to_unlock() 1
+
+static inline int
+__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
+{
+ /*
+ * We have two variants here. The cmpxchg based one is the best one
+ * because it never induce a false contention state. It is included
+ * here because architectures using the inc/dec algorithms over the
+ * xchg ones are much more likely to support cmpxchg natively.
+ *
+ * If not we fall back to the spinlock based variant - that is
+ * just as efficient (and simpler) as a 'destructive' probing of
+ * the mutex state would be.
+ */
+#ifdef __HAVE_ARCH_CMPXCHG
+ if (likely(atomic_cmpxchg(count, 1, 0) == 1)) {
+ smp_mb();
+ return 1;
+ }
+ return 0;
+#else
+ return fail_fn(count);
+#endif
+}
+
+#endif
+
+#endif