From: Stanislav Kinsbursky <skinsbursky@parallels.com>
Date: Mon, 24 Jun 2013 07:52:38 +0000 (+0400)
Subject: SUNRPC: fix races on PipeFS MOUNT notifications
X-Git-Tag: v3.11-rc1~72^2~10
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=384816051ca9125cd54750e59c780c2a2655fa4f;p=pandora-kernel.git

SUNRPC: fix races on PipeFS MOUNT notifications

Below are races, when RPC client can be created without PiepFS dentries

CPU#0					CPU#1
-----------------------------		-----------------------------
rpc_new_client				rpc_fill_super
rpc_setup_pipedir
mutex_lock(&sn->pipefs_sb_lock)
rpc_get_sb_net == NULL
(no per-net PipeFS superblock)
					sn->pipefs_sb = sb;
					notifier_call_chain(MOUNT)
					(client is not in the list)
rpc_register_client
(client without pipes dentries)

To fix this patch:
1) makes PipeFS mount notification call with pipefs_sb_lock being held.
2) releases pipefs_sb_lock on new SUNRPC client creation only after
registration.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

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