Re: [PATCH RT] rt: Make cpu_chill() use hrtimer instead of msleep()

[Sebastian Andrzej Siewior]

* Steven Rostedt | 2014-02-05 11:51:25 [-0500]:

>Ulrich Obergfell pointed out that cpu_chill() calls msleep() which is woken
>up by the ksoftirqd running the TIMER softirq. But as the cpu_chill() is
>called from softirq context, it may block the ksoftirqd() from running, in
>which case, it may never wake up the msleep() causing the deadlock.
>
>I checked the vmcore, and irq/74-qla2xxx is stuck in the msleep() call,
>running on CPU 8. The one ksoftirqd that is stuck, happens to be the one that
>runs on CPU 8, and it is blocked on a lock held by irq/74-qla2xxx. As that
>ksoftirqd is the one that will wake up irq/74-qla2xxx, and it happens to be
>blocked on a lock that irq/74-qla2xxx holds, we have our deadlock.

could you please tell me which two locks are invovled here?

Sebastian
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