Date: Thu, 10 May 2007 16:23:13 -0400
To: Doug Chapman <doug.chapman@hp.com>
Cc: linux-kernel@vger.kernel.org, hch@infradead.org,
       Marc Eshel <eshel@almaden.ibm.com>
Subject: Re: post 2.6.21 regression in F_GETLK
Message-ID: <20070510202313.GV13719@fieldses.org>
References: <1178823375.7247.11.camel@dchapman.boston.redhat.com> <20070510193050.GQ13719@fieldses.org> <20070510193859.GR13719@fieldses.org>
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From: "J. Bruce Fields" <bfields@fieldses.org>
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On Thu, May 10, 2007 at 03:38:59PM -0400, bfields wrote:
> On Thu, May 10, 2007 at 03:30:50PM -0400, bfields wrote:
> > On Thu, May 10, 2007 at 02:56:15PM -0400, Doug Chapman wrote:
> > > A recent regression (introduced after 2.6.21) was caught by the LTP test
> > > fcntl11.  It appears that F_GETLK is not properly checking for existing
> > > F_RDLCK and allows taking out a write lock.

Hm, actually, could you double-check the test results?  Looking at your
test case, it appears that it fails when the lock returned from the
fcntl(.,F_GETLK,.) has an l_type != F_RDLCK.  That doesn't necessarily
mean the F_GETLK is reporting no conflict.  I believe the bug is
actually that it's reporting the wrong kind of conflict--so it's
returning l_type == F_WRLCK, not F_UNLCK.

Also, this affects only F_GETLK, not F_SETLK, so you're not actually
managing to acquire a conflicting lock, right?

--b.
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