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Groups > linux.kernel > #1241552
| From | Tejun Heo <tj@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC v2 07/18] kthread: Allow to cancel kthread work |
| Date | 2015-10-07 16:30 +0200 |
| Message-ID | <qgXTc-7qA-23@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <qfaKS-7Fv-1@gated-at.bofh.it> <qfebL-4hK-3@gated-at.bofh.it> <qgaSu-4bV-19@gated-at.bofh.it> <qgbOy-5x8-27@gated-at.bofh.it> <qgTcR-DX-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Hello, Petr. On Wed, Oct 07, 2015 at 11:21:30AM +0200, Petr Mladek wrote: > Now, let's have one work: W, two workers: A, B, and try to queue > the same work to the two workers at the same time: It's a debug WARN condition to catch silly mistakes. It can have minor race conditions. ... > Second, we still need the busy waiting for the pending timer callback. Isn't that del_timer_sync()? > Yes, we could set some flag so that the call back does not queue > the work. But cancel_kthread_work_sync() still has to wait. > It could not return if there is still some pending operation > with the struct kthread_work. Otherwise, it never could > be freed a safe way. > > Also note that we still need the WORK_PENDING flag. Otherwise, we > would not be able to detect the race when timer is removed but > the callback has not run yet. Yeah, just use a state field as I wrote before. > Let me to repeat that using per-work and per-worker lock is not an > option either. We would need some crazy hacks to avoid ABBA deadlocks. > > > All in all, I would prefer to keep the original approach that is > heavily inspired by the workqueues. I think that it is actually > an advantage to reuse some working concept that reinventing wheels. At each turn, you come up with non-issues and declare that it needs to be full workqueue-like implementation but the issues you're raising seem all rather irrelevant. Can you please try to take a step back and put some distance from the implementation details of workqueue? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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Re: [RFC v2 07/18] kthread: Allow to cancel kthread work Petr Mladek <pmladek@suse.com> - 2015-10-07 11:30 +0200
Re: [RFC v2 07/18] kthread: Allow to cancel kthread work Tejun Heo <tj@kernel.org> - 2015-10-07 16:30 +0200
Re: [RFC v2 07/18] kthread: Allow to cancel kthread work Petr Mladek <pmladek@suse.com> - 2015-10-14 12:30 +0200
Re: [RFC v2 07/18] kthread: Allow to cancel kthread work Tejun Heo <tj@kernel.org> - 2015-10-14 19:40 +0200
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