From: Jeremy Allison <jra@samba.org>
To: Stuart_Hayes@Dell.com
Cc: jra@samba.org, michael@wil.cx, linux-fsdevel@vger.kernel.org
Subject: Re: posix_lock_deadlocks() hang
Date: Tue, 14 Sep 2004 12:28:14 -0700 [thread overview]
Message-ID: <20040914192814.GE16151@jeremy1> (raw)
In-Reply-To: <7A8F92187EF7A249BF847F1BF4903C040AFBF3@ausx2kmpc103.aus.amer.dell.com>
On Tue, Sep 14, 2004 at 02:23:29PM -0500, Stuart_Hayes@Dell.com wrote:
> Jeremy Allison wrote:
> > On Mon, Sep 13, 2004 at 03:25:41PM -0500, Stuart_Hayes@Dell.com wrote:
> >>
> >> I am seeing the kernel get stuck in an endless loop in
> >> posix_locks_deadlock() checking for deadlocks.
> >>
> >> It appears that samba (smbd) is getting both flocks and posix locks.
> >> Since flock_lock_file() isn't checking for potential deadlocks before
> >> adding lock requests to the blocked_list, we end up with (what
> >> appears to be) a circular dependency between a posix lock and an
> >> flock in blocked_list.
> >
> > I'm not aware that we obtain any locks with flock. We only use fcntl
> > (POSIX) locks. I just grepped the code so I'm quite sure :-).
> >
> > Jeremy.
>
> I haven't specifically traced your application, but, while debugging the
> locking code, I definitely saw smbd requesting both flocks and posix
> locks.
>
> Also, looking at Samba version 3.0.6, from Red Hat Enterprise Linux, and
> I see
> source/smbd/open.c: if (kernel_mode) flock(fsp->fd, kernel_mode);
> among other grep matches.
>
> I just checked 3.0.7, and it seems to do the same thing.
Yes, that's only if #if HAVE_KERNEL_SHARE_MODES is defined,
which is not turned on by default. That's only done if someone
sets it by hand (it's not autoconf tested). It's also not a
standard flock (to lock files) but a request for a share mode
in the kernel.
Did you turn this on ?
Jeremy.
next prev parent reply other threads:[~2004-09-14 19:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-14 19:23 posix_lock_deadlocks() hang Stuart_Hayes
2004-09-14 19:28 ` Jeremy Allison [this message]
2004-09-14 19:30 ` Jeremy Allison
-- strict thread matches above, loose matches on Subject: below --
2004-09-17 16:21 Stuart_Hayes
2004-09-14 14:43 Stuart_Hayes
2004-09-13 20:25 Stuart_Hayes
2004-09-14 0:55 ` Matthew Wilcox
2004-09-14 19:09 ` Jeremy Allison
2004-09-14 23:23 ` Stephen Rothwell
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