From: Stanislav Kinsbursky <skinsbursky@parallels.com>
To: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devel@openvz.org" <devel@openvz.org>
Subject: Re: [PATCH v2] SUNRPC: skip dead but not buried clients on PipeFS events
Date: Thu, 26 Apr 2012 10:31:45 +0400 [thread overview]
Message-ID: <4F98EBD1.2070808@parallels.com> (raw)
In-Reply-To: <20120425173005.GD751@fieldses.org>
25.04.2012 21:30, J. Bruce Fields написал:
> On Fri, Apr 20, 2012 at 06:11:02PM +0400, Stanislav Kinsbursky wrote:
>> v2: atomic_inc_return() was replaced by atomic_inc_not_zero().
>>
>> These clients can't be safely dereferenced if their counter in 0.
> I'm pretty confused by how these notifiers work....
>
> rpc_release_client decrements cl_count to zero temporarily, to have it
> immediately re-incremented by rpc_free_auth.
>
> So if we're called concurrently with rpc_release_client then it's sort
> of random whether someone gets this callback.
>
> Is that a problem?
>
> Also, is this an existing bug? (In which case Trond should take it
> now.)
Sorry, I was mistaken in previous letter.
Yes, this is an existent bug.
I.e. without this patch notifier can dereference a client, which is
actually dead already, but haven't deleted itself from the client's list.
And then notifier will try to work with this client and even release it
at the end.
prev parent reply other threads:[~2012-04-26 6:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 14:11 [PATCH v2] SUNRPC: skip dead but not buried clients on PipeFS events Stanislav Kinsbursky
2012-04-25 17:30 ` J. Bruce Fields
2012-04-25 18:54 ` Myklebust, Trond
2012-04-25 21:14 ` Stanislav Kinsbursky
2012-04-26 6:31 ` Stanislav Kinsbursky [this message]
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