[PATCH] mqueue: sys_mq_open: do not call mnt_drop_write() if read-only

From: Vladimir Davydov
Date: Tue Mar 19 2013 - 05:31:58 EST

mnt_drop_write() must be called only if mnt_want_write() succeeded,
otherwise the mnt_writers counter will diverge.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Doug Ledford <dledford@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
ipc/mqueue.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index e5c4f60..3953fda 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -840,7 +840,8 @@ out_putfd:
fd = error;
- mnt_drop_write(mnt);
+ if (!ro)
+ mnt_drop_write(mnt);
return fd;

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