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From Manoj Kasichainula <>
Subject Re: fcntl hanging without anyone holding the lock?
Date Thu, 22 Apr 1999 20:24:03 GMT
On Tue, Apr 20, 1999 at 10:15:40PM -0700, Dean Gaudet wrote:
> The fcntl() stuff is shared by the CLONE_FS option to clone() -- are you
> sure the linuxthread manager thread isn't still hanging around with the
> shared struct?

The manager thread is definitely hanging around in this case, as its
supposed to. But it's not holding the lock (at least as far as lsof
knows). Is this what you mean?

> Your best bet right now is to hack up the test/test-mutex (or whatever
> it's called) and reproduce the problem... make a small test case and mail
> it to linux-kernel.  This sounds like a kernel bug.

I'm working on this. Just wrapping the fcntl with
pthread_mutex_[un]locks didn't trigger the problem. But, this bug
isn't triggered when the child processes are gracefully shutdown (i.e.

lsof will report a *thread* as having a lock rather than each thread
in the process. My gut feeling is that we're hitting the same problem
as pthread process locks, and that a thread with the lock that dies
doesn't release its lock. I don't know why this would be triggered by
the pthread calls wrapping fcntl, though.
Manoj Kasichainula - manojk at io dot com -
"if it ain't broke, break it." -- Ray Brune

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