cfab9d0e1d
The parenthesis around "likely" used in ia64 __mutex_fastpath_trylock is incorrect, and it leads to broken mutex_trylock. Here is the patch that fixed the bug. I removed the likely altogether because there is no branch and gcc does a reasonable job at predicating the return value. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
/*
|
|
* ia64 implementation of the mutex fastpath.
|
|
*
|
|
* Copyright (C) 2006 Ken Chen <kenneth.w.chen@intel.com>
|
|
*
|
|
*/
|
|
|
|
#ifndef _ASM_MUTEX_H
|
|
#define _ASM_MUTEX_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, void (*fail_fn)(atomic_t *))
|
|
{
|
|
if (unlikely(ia64_fetchadd4_acq(count, -1) != 1))
|
|
fail_fn(count);
|
|
}
|
|
|
|
/**
|
|
* __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, int (*fail_fn)(atomic_t *))
|
|
{
|
|
if (unlikely(ia64_fetchadd4_acq(count, -1) != 1))
|
|
return fail_fn(count);
|
|
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, void (*fail_fn)(atomic_t *))
|
|
{
|
|
int ret = ia64_fetchadd4_rel(count, 1);
|
|
if (unlikely(ret < 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 *))
|
|
{
|
|
if (cmpxchg_acq(count, 1, 0) == 1)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
#endif
|