From 15724ecb7e9bab35fc694c666ad563adba820cc3 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 8 Jul 2013 16:01:13 -0700 Subject: 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 Cc: Andi Kleen Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/msg.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'ipc') diff --git a/ipc/msg.c b/ipc/msg.c index f62fa5eed84..de422ff71c8 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: -- cgit v1.2.3-70-g09d2