On 09/27/2012 02:28 AM, Tejun Heo wrote:
> On Thu, Sep 27, 2012 at 01:20:35AM +0800, Lai Jiangshan wrote:
>> is_chained_work() is too complicated. we can simply found out
>> whether current task is worker by PF_WQ_WORKER or wq->rescuer.
>>
>> Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
>> ---
>> kernel/workqueue.c | 36 ++++++++++++------------------------
>> 1 files changed, 12 insertions(+), 24 deletions(-)
>>
>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
>> index e41c562..c718b94 100644
>> --- a/kernel/workqueue.c
>> +++ b/kernel/workqueue.c
>> @@ -1182,34 +1182,22 @@ static void insert_work(struct cpu_workqueue_struct
>> *cwq,
>>
>> /*
>> * Test whether @work is being queued from another work executing on the
>> - * same workqueue. This is rather expensive and should only be used from
>> - * cold paths.
>> + * same workqueue.
>> */
>> static bool is_chained_work(struct workqueue_struct *wq)
>> {
>> - unsigned long flags;
>> - unsigned int cpu;
>> + struct worker *worker = NULL;
>>
>> - for_each_gcwq_cpu(cpu) {
>> - struct global_cwq *gcwq = get_gcwq(cpu);
>> - struct worker *worker;
>> - struct hlist_node *pos;
>> - int i;
>> + if (wq->rescuer && current == wq->rescuer->task) /* rescuer_thread() */
>> + worker = wq->rescuer;
>> + else if (current->flags & PF_WQ_WORKER) /* worker_thread() */
>> + worker = kthread_data(current);
>>
>> - spin_lock_irqsave(&gcwq->lock, flags);
>> - for_each_busy_worker(worker, i, pos, gcwq) {
>> - if (worker->task != current)
>> - continue;
>> - spin_unlock_irqrestore(&gcwq->lock, flags);
>> - /*
>> - * I'm @worker, no locking necessary. See if @work
>> - * is headed to the same workqueue.
>> - */
>> - return worker->current_cwq->wq == wq;
>> - }
>> - spin_unlock_irqrestore(&gcwq->lock, flags);
>> - }
>> - return false;
>> + /*
>> + * I'm @worker, no locking necessary. See if @work
>> + * is headed to the same workqueue.
>> + */
>> + return worker && worker->current_cwq->wq == wq;
if current is a worker and ...
>
> How about,
>
> if (wq->rescuer && current == wq->rescuer->task)
> worker = wq->rescuer;
> else if (current->flags & PF_WQ_WORKER)
> worker = kthread_data(current);
> else
> return NULL;
>
> return worker->curent_cwq->wq == wq;
>
Hi, Tejun
Your code is good, but I don't think I need to resend(and use your code).
Main reason: I think the readability of your is the same as mine,
and your add two lines.
Tiny reason: my code uses only one return. (I don't always keep one return,
but I try to keep it if it is still clean)
Is there any other reason to change it?
Thanks,
Lai.
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