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| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-07-08 16:01:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-09 10:33:27 -0700 |
| commit | 15724ecb7e9bab35fc694c666ad563adba820cc3 (patch) | |
| tree | d9ae089252e84327367056a29c0cf6b16f844c2e /ipc | |
| parent | 7b4cc5d8411bd4e9d61d8714f53859740cf830c2 (diff) | |
| download | lwn-15724ecb7e9bab35fc694c666ad563adba820cc3.tar.gz lwn-15724ecb7e9bab35fc694c666ad563adba820cc3.zip | |
ipc,msg: shorten critical region in msgctl_down
Instead of holding the ipc lock for the entire function, use the
ipcctl_pre_down_nolock and only acquire the lock for specific commands:
RMID and SET.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
| -rw-r--r-- | ipc/msg.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index f62fa5eed847..de422ff71c87 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -410,11 +410,10 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, down_write(&msg_ids(ns).rw_mutex); rcu_read_lock(); - ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd, - &msqid64.msg_perm, msqid64.msg_qbytes); + ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd, + &msqid64.msg_perm, msqid64.msg_qbytes); if (IS_ERR(ipcp)) { err = PTR_ERR(ipcp); - /* the ipc lock is not held upon failure */ goto out_unlock1; } @@ -422,10 +421,11 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, err = security_msg_queue_msgctl(msq, cmd); if (err) - goto out_unlock0; + goto out_unlock1; switch (cmd) { case IPC_RMID: + ipc_lock_object(&msq->q_perm); /* freeque unlocks the ipc object and rcu */ freeque(ns, ipcp); goto out_up; @@ -433,9 +433,10 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, if (msqid64.msg_qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) { err = -EPERM; - goto out_unlock0; + goto out_unlock1; } + ipc_lock_object(&msq->q_perm); err = ipc_update_perm(&msqid64.msg_perm, ipcp); if (err) goto out_unlock0; @@ -454,6 +455,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, break; default: err = -EINVAL; + goto out_unlock1; } out_unlock0: |