Blackfin: punt unused/wrong mutex-dec.h

/*

 * include/asm-generic/mutex-dec.h

 *

 * Generic implementation of the mutex fastpath, based on atomic

 * decrement/increment.

 */

#ifndef _ASM_GENERIC_MUTEX_DEC_H

#define _ASM_GENERIC_MUTEX_DEC_H

/**

 *  __mutex_fastpath_lock - try to take the lock by moving the count

 *                          from 1 to a 0 value

 *  @count: pointer of type atomic_t

 *  @fail_fn: function to call if the original value was not 1

 *

 * Change the count from 1 to a value lower than 1, and call <fail_fn> if

 * it wasn't 1 originally. This function MUST leave the value lower than

 * 1 even when the "1" assertion wasn't true.

 */

static inline void

__mutex_fastpath_lock(atomic_t *count, fastcall void (*fail_fn)(atomic_t *))

{

	if (unlikely(atomic_dec_return(count) < 0))

		fail_fn(count);

	else

		smp_mb();

}

/**

 *  __mutex_fastpath_lock_retval - try to take the lock by moving the count

 *                                 from 1 to a 0 value

 *  @count: pointer of type atomic_t

 *  @fail_fn: function to call if the original value was not 1

 *

 * Change the count from 1 to a value lower than 1, and call <fail_fn> if

 * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,

 * or anything the slow path function returns.

 */

static inline int

__mutex_fastpath_lock_retval(atomic_t *count, fastcall int (*fail_fn)(atomic_t *))

{

	if (unlikely(atomic_dec_return(count) < 0))

		return fail_fn(count);

	else {

		smp_mb();

		return 0;

	}

}

/**

 *  __mutex_fastpath_unlock - try to promote the count from 0 to 1

 *  @count: pointer of type atomic_t

 *  @fail_fn: function to call if the original value was not 0

 *

 * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.

 * In the failure case, this function is allowed to either set the value to

 * 1, or to set it to a value lower than 1.

 *

 * If the implementation sets it to a value of lower than 1, then the

 * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs

 * to return 0 otherwise.

 */

static inline void

__mutex_fastpath_unlock(atomic_t *count, fastcall void (*fail_fn)(atomic_t *))

{

	smp_mb();

	if (unlikely(atomic_inc_return(count) <= 0))

		fail_fn(count);

}

#define __mutex_slowpath_needs_to_unlock()		1

/**

 * __mutex_fastpath_trylock - try to acquire the mutex, without waiting

 *

 *  @count: pointer of type atomic_t

 *  @fail_fn: fallback function

 *

 * Change the count from 1 to a value lower than 1, and return 0 (failure)

 * if it wasn't 1 originally, or return 1 (success) otherwise. This function

 * MUST leave the value lower than 1 even when the "1" assertion wasn't true.

 * Additionally, if the value was < 0 originally, this function must not leave

 * it to 0 on failure.

 *

 * If the architecture has no effective trylock variant, it should call the

 * <fail_fn> spinlock-based trylock variant unconditionally.

 */

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