Subject: + ipcmsg-make-msgctl_nolock-lockless.patch added to -mm tree
To: davidlohr.bueso@xxxxxx,andi@xxxxxxxxxxxxxx,riel@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 24 May 2013 13:17:41 -0700
The patch titled
Subject: ipc,msg: make msgctl_nolock lockless
has been added to the -mm tree. Its filename is
ipcmsg-make-msgctl_nolock-lockless.patch
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From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Subject: 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 <davidlohr.bueso@xxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msg.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff -puN ipc/msg.c~ipcmsg-make-msgctl_nolock-lockless ipc/msg.c
--- a/ipc/msg.c~ipcmsg-make-msgctl_nolock-lockless
+++ a/ipc/msg.c
@@ -547,17 +547,25 @@ static int msgctl_nolock(struct ipc_name
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;
@@ -566,8 +574,6 @@ static int msgctl_nolock(struct ipc_name
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;
@@ -577,7 +583,8 @@ static int msgctl_nolock(struct ipc_name
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;
@@ -589,7 +596,7 @@ static int msgctl_nolock(struct ipc_name
return err;
out_unlock:
- msg_unlock(msq);
+ rcu_read_unlock();
return err;
}
_
Patches currently in -mm which might be from davidlohr.bueso@xxxxxx are
linux-next.patch
shm-fix-null-pointer-deref-when-userspace-specifies-invalid-hugepage-size-fix.patch
softirq-use-_ret_ip_.patch
ipc-move-rcu-lock-out-of-ipc_addid.patch
ipc-introduce-ipc-object-locking-helpers.patch
ipc-close-open-coded-spin-lock-calls.patch
ipc-move-locking-out-of-ipcctl_pre_down_nolock.patch
ipcmsg-shorten-critical-region-in-msgctl_down.patch
ipcmsg-introduce-msgctl_nolock.patch
ipcmsg-introduce-lockless-functions-to-obtain-the-ipc-object.patch
ipcmsg-make-msgctl_nolock-lockless.patch
ipcmsg-shorten-critical-region-in-msgsnd.patch
ipcmsg-shorten-critical-region-in-msgrcv.patch
ipc-remove-unused-functions.patch
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