diff options
| author | Davidlohr Bueso <[email protected]> | 2013-07-08 16:01:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2013-07-09 10:33:27 -0700 |
| commit | ac0ba20ea6f2201a1589d6dc26ad1a4f0f967bb8 (patch) | |
| tree | bc3e2e4c4140f07ee1861b724ba7e1b295d7bbc6 | |
| parent | a5001a0d9768568de5d613c3b3a5b9c7721299da (diff) | |
| download | linux-ac0ba20ea6f2201a1589d6dc26ad1a4f0f967bb8.tar.gz | |
ipc,msg: make msgctl_nolock lockless
While the INFO cmd doesn't take the ipc lock, the STAT commands do
acquire it unnecessarily. We can do the permissions and security checks
only holding the rcu lock.
This function now mimics semctl_nolock().
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | ipc/msg.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index c53c1371606441..c218328b59806f 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -545,17 +545,25 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (!buf) return -EFAULT; + memset(&tbuf, 0, sizeof(tbuf)); + + rcu_read_lock(); if (cmd == MSG_STAT) { - msq = msg_lock(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = msq->q_perm.id; } else { - msq = msg_lock_check(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object_check(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = 0; } + err = -EACCES; if (ipcperms(ns, &msq->q_perm, S_IRUGO)) goto out_unlock; @@ -564,8 +572,6 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (err) goto out_unlock; - memset(&tbuf, 0, sizeof(tbuf)); - kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); tbuf.msg_stime = msq->q_stime; tbuf.msg_rtime = msq->q_rtime; @@ -575,7 +581,8 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, tbuf.msg_qbytes = msq->q_qbytes; tbuf.msg_lspid = msq->q_lspid; tbuf.msg_lrpid = msq->q_lrpid; - msg_unlock(msq); + rcu_read_unlock(); + if (copy_msqid_to_user(buf, &tbuf, version)) return -EFAULT; return success_return; @@ -587,7 +594,7 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, return err; out_unlock: - msg_unlock(msq); + rcu_read_unlock(); return err; } |