On Tue, Aug 21, 2012 at 09:43:07AM -0700, tip-bot for Tejun Heo wrote: > Commit-ID: c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 > Gitweb: http://git.kernel.org/tip/c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 > Author: Tejun Heo <tj@xxxxxxxxxx> > AuthorDate: Wed, 8 Aug 2012 11:10:28 -0700 > Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > CommitDate: Tue, 21 Aug 2012 16:28:31 +0200 > > timer: Implement TIMER_IRQSAFE > > Timer internals are protected with irq-safe locks but timer execution > isn't, so a timer being dequeued for execution and its execution > aren't atomic against IRQs. This makes it impossible to wait for its > completion from IRQ handlers and difficult to shoot down a timer from > IRQ handlers. > > This issue caused some issues for delayed_work interface. Because > there's no way to reliably shoot down delayed_work->timer from IRQ > handlers, __cancel_delayed_work() can't share the logic to steal the > target delayed_work with cancel_delayed_work_sync(), and can only > steal delayed_works which are on queued on timer. Similarly, the > pending mod_delayed_work() can't be used from IRQ handlers. > > This patch adds a new timer flag TIMER_IRQSAFE, which makes the timer > to be executed without enabling IRQ after dequeueing such that its > dequeueing and execution are atomic against IRQ handlers. > > This makes it safe to wait for the timer's completion from IRQ > handlers, for example, using del_timer_sync(). It can never be > executing on the local CPU and if executing on other CPUs it won't be > interrupted until done. > > This will enable simplifying delayed_work cancel/mod interface. > > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> > Cc: torvalds@xxxxxxxxxxxxxxxxxxxx > Cc: peterz@xxxxxxxxxxxxx > Link: http://lkml.kernel.org/r/1344449428-24962-5-git-send-email-tj@xxxxxxxxxx > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Will pull into wq/for-3.7 and put delay_work changes on top. If there's any objection, please scream. Thanks a lot. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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