From: Davidlohr Bueso Date: Mon, 8 Jul 2013 23:01:16 +0000 (-0700) Subject: ipc,msg: make msgctl_nolock lockless X-Git-Tag: upstream/snapshot3+hdmi~4756^2~33 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ac0ba20ea6f2201a1589d6dc26ad1a4f0f967bb8;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git 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 Cc: Andi Kleen Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/ipc/msg.c b/ipc/msg.c index c53c137..c218328 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; }