On Wed, Jun 4, 2014 at 4:38 PM, Pranith Kumar <pran...@gatech.edu> wrote:
> remove a redundant comparision
>
> Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
> ---
> kernel/locking/rwsem-xadd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
> index 1f99664b..6f8bd3c 100644
> --- a/kernel/locking/rwsem-xadd.c
> +++ b/kernel/locking/rwsem-xadd.c
> @@ -249,8 +249,7 @@ static inline bool rwsem_try_write_lock(long count,
> struct rw_semaphore *sem)
> {
> if (!(count & RWSEM_ACTIVE_MASK)) {
> /* try acquiring the write lock */
> - if (sem->count == RWSEM_WAITING_BIAS &&
> - cmpxchg(&sem->count, RWSEM_WAITING_BIAS,
> + if (cmpxchg(&sem->count, RWSEM_WAITING_BIAS,
> RWSEM_ACTIVE_WRITE_BIAS) == RWSEM_WAITING_BIAS) {
This was mainly done to avoid the cost of a cmpxchg in case where they
are not equal. Not sure if it really makes a difference though.
--
Andev
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