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: default avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a5001a0d
...@@ -545,17 +545,25 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, ...@@ -545,17 +545,25 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
if (!buf) if (!buf)
return -EFAULT; return -EFAULT;
memset(&tbuf, 0, sizeof(tbuf));
rcu_read_lock();
if (cmd == MSG_STAT) { if (cmd == MSG_STAT) {
msq = msg_lock(ns, msqid); msq = msq_obtain_object(ns, msqid);
if (IS_ERR(msq)) if (IS_ERR(msq)) {
return PTR_ERR(msq); err = PTR_ERR(msq);
goto out_unlock;
}
success_return = msq->q_perm.id; success_return = msq->q_perm.id;
} else { } else {
msq = msg_lock_check(ns, msqid); msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) if (IS_ERR(msq)) {
return PTR_ERR(msq); err = PTR_ERR(msq);
goto out_unlock;
}
success_return = 0; success_return = 0;
} }
err = -EACCES; err = -EACCES;
if (ipcperms(ns, &msq->q_perm, S_IRUGO)) if (ipcperms(ns, &msq->q_perm, S_IRUGO))
goto out_unlock; goto out_unlock;
...@@ -564,8 +572,6 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, ...@@ -564,8 +572,6 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
if (err) if (err)
goto out_unlock; goto out_unlock;
memset(&tbuf, 0, sizeof(tbuf));
kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
tbuf.msg_stime = msq->q_stime; tbuf.msg_stime = msq->q_stime;
tbuf.msg_rtime = msq->q_rtime; tbuf.msg_rtime = msq->q_rtime;
...@@ -575,7 +581,8 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, ...@@ -575,7 +581,8 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
tbuf.msg_qbytes = msq->q_qbytes; tbuf.msg_qbytes = msq->q_qbytes;
tbuf.msg_lspid = msq->q_lspid; tbuf.msg_lspid = msq->q_lspid;
tbuf.msg_lrpid = msq->q_lrpid; tbuf.msg_lrpid = msq->q_lrpid;
msg_unlock(msq); rcu_read_unlock();
if (copy_msqid_to_user(buf, &tbuf, version)) if (copy_msqid_to_user(buf, &tbuf, version))
return -EFAULT; return -EFAULT;
return success_return; return success_return;
...@@ -587,7 +594,7 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, ...@@ -587,7 +594,7 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
return err; return err;
out_unlock: out_unlock:
msg_unlock(msq); rcu_read_unlock();
return err; return err;
} }
......
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