Commit ac0ba20e authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds

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: 's avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a5001a0d
......@@ -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;
}
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment