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SubjectRe: [PATCH 3/8] sched/wait: Use __add_wait_queue{_tail}_exclusive() as possible.
On 04/15/2014 10:49 PM, Peter Zijlstra wrote:
> On Tue, Apr 15, 2014 at 09:32:52PM +0900, Dongsheng Yang wrote:
>> From: Dongsheng <yangds.fnst@cn.fujitsu.com>
>>
>> There is already a function in include/linux/wait.h to cover the
>> 'exclusive' usage. So we can use it in sched/wait.c to replace
>> the opened implementation of it.
>>
>> Signed-off-by: Dongsheng <yangds.fnst@cn.fujitsu.com>
>> ---
>> kernel/sched/wait.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
>> index 283750e..b04827e 100644
>> --- a/kernel/sched/wait.c
>> +++ b/kernel/sched/wait.c
>> @@ -38,9 +38,8 @@ void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
>> unsigned long flags;
>>
>> trace_sched_wait(current);
>> - wait->flags |= WQ_FLAG_EXCLUSIVE;
>> spin_lock_irqsave(&q->lock, flags);
>> - __add_wait_queue_tail(q, wait);
>> + __add_wait_queue_tail_exclusive(q, wait);
>> spin_unlock_irqrestore(&q->lock, flags);
>> }
>> EXPORT_SYMBOL(add_wait_queue_exclusive);
>> @@ -192,10 +191,9 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
>> unsigned long flags;
>>
>> trace_sched_wait(current);
>> - wait->flags |= WQ_FLAG_EXCLUSIVE;
>> spin_lock_irqsave(&q->lock, flags);
>> if (list_empty(&wait->task_list))
>> - __add_wait_queue_tail(q, wait);
>> + __add_wait_queue_tail_exclusive(q, wait);
>> set_current_state(state);
>> spin_unlock_irqrestore(&q->lock, flags);
> That is not a no-op, if !list_empty() we loose the WQ_flag

Oh, yes, my mistake. Thanx
> .
>



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