svn commit: r196293 - head/sys/kern

Pawel Jakub Dawidek pjd at FreeBSD.org
Mon Aug 17 21:19:51 UTC 2009


On Mon, Aug 17, 2009 at 08:36:12AM -0700, Sam Leffler wrote:
> Pawel Jakub Dawidek wrote:
> >Author: pjd
> >Date: Mon Aug 17 08:42:34 2009
> >New Revision: 196293
> >URL: http://svn.freebsd.org/changeset/base/196293
> >
> >Log:
> >  Because taskqueue_run() can drop tq_mutex, we need to check if the
> >  TQ_FLAGS_ACTIVE flag wasn't removed in the meantime, which means we 
> >  missed a
> >  wakeup.
> 
> So this would leave a task q thread running? [...]

Sleeping infinitely to be precise.

> [...] Can you describe the 
> scenario that demonstrated this problem?

Once I moved ZFS from taskq ported from OpenSolaris to wrapper around
our taskqueue(9), the deadlock was easy to trigger (I experienced it by
testing with fsstress).

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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