Messages in this thread | | | Date | Fri, 28 Sep 2012 17:52:02 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH 04/12] workqueue: simplify is_chained_work() |
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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 <laijs@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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