Messages in this thread | | | Date | Fri, 07 Feb 2014 15:21:46 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH RT] rt: Make cpu_chill() use hrtimer instead of msleep() |
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On 02/07/2014 03:13 PM, Steven Rostedt wrote: > On Fri, 7 Feb 2014 09:08:34 -0500 > Steven Rostedt <rostedt@goodmis.org> wrote: > > >>> could you please tell me which two locks are invovled here? > > I should have also stated that it was only one lock that was involved. > But the lock owner was doing a msleep() that requires a wakeup by > ksoftirqd to continue. If ksoftirqd happens to be blocked on a lock > held by the msleep() caller, then you have your deadlock.
That makes sense.
> It's best not to have any softirqs going to sleep requiring another > softirq to wake it up. Note, if we ever require a timer softirq to do a > cpu_chill() it will most definitely hit this deadlock.
Yes. And that sleep in softirq is also not really nice but this isn't new. Thanks for the patch & explanation. > > -- Steve
Sebastian
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