From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Christian Krafft <krafft@de.ibm.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [patch] nfs: fix locking in nfs/inode.c in nfs_free_open_context
Date: Wed, 25 Jul 2007 13:28:22 -0400 [thread overview]
Message-ID: <1185384502.6585.97.camel@localhost> (raw)
In-Reply-To: <20070725170837.5fba5fd1@localhost>
On Wed, 2007-07-25 at 17:08 +0200, Christian Krafft wrote:
> Obviously the locking code in nfs_free_open_context is wrong.
> Checking the list for entries and removing the entry should be an atomic operation.
Wrong. It is quite safe to test the structure member ctx->list for
emptiness outside the spinlock because we have an explicit guarantee
that nobody else has a reference to this structure, plus the
atomic_dec_and_test() in kref_put() has acted as a memory barrier for
us.
> Also list_del_init should be used, because list_del will leave the empty list in
> an undefined condition.
Huh? We're freeing the context. It will _never_ _ever_ _ever_ be used
again. If anything tries to use ctx->list after this, then that is a
major bug.
Patch rejected...
Trond
next prev parent reply other threads:[~2007-07-25 17:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-25 15:08 [patch] nfs: fix locking in nfs/inode.c in nfs_free_open_context Christian Krafft
2007-07-25 17:28 ` Trond Myklebust [this message]
2007-07-26 11:23 ` Arnd Bergmann
2007-07-26 12:37 ` Trond Myklebust
2007-07-26 12:44 ` Christian Krafft
2007-07-26 13:23 ` Trond Myklebust
2007-07-26 15:13 ` Arnd Bergmann
2007-07-26 16:08 ` Trond Myklebust
2007-07-26 18:00 ` Christian Krafft
2007-07-27 10:02 ` Christian Krafft
2007-07-27 9:44 ` Arnd Bergmann
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