Messages in this thread Patch in this message | | | From | Davidlohr Bueso <> | Subject | [PATCH 05/11] ipc,msg: shorten critical region in msgctl_down | Date | Wed, 15 May 2013 18:08:04 -0700 |
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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> --- ipc/msg.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/ipc/msg.c b/ipc/msg.c index 4eaeb08..264ebe0 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -412,11 +412,10 @@ 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; } @@ -424,10 +423,11 @@ 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; @@ -435,9 +435,10 @@ 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; @@ -456,6 +457,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, break; default: err = -EINVAL; + goto out_unlock1; } out_unlock0: -- 1.7.11.7
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