Subject: + ipcmsg-shorten-critical-region-in-msgctl_down.patch added to -mm tree
To: davidlohr.bueso@xxxxxx,andi@xxxxxxxxxxxxxx,riel@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 24 May 2013 13:17:38 -0700
The patch titled
Subject: ipc,msg: shorten critical region in msgctl_down
has been added to the -mm tree. Its filename is
ipcmsg-shorten-critical-region-in-msgctl_down.patch
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From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Subject: ipc,msg: shorten critical region in msgctl_down
Instead of holding the ipc lock for the entire function, use the
ipcctl_pre_down_nolock and only acquire the lock for specific commands:
RMID and SET.
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 | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff -puN ipc/msg.c~ipcmsg-shorten-critical-region-in-msgctl_down ipc/msg.c
--- a/ipc/msg.c~ipcmsg-shorten-critical-region-in-msgctl_down
+++ a/ipc/msg.c
@@ -412,11 +412,10 @@ static int msgctl_down(struct ipc_namesp
down_write(&msg_ids(ns).rw_mutex);
rcu_read_lock();
- ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd,
- &msqid64.msg_perm, msqid64.msg_qbytes);
+ ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
+ &msqid64.msg_perm, msqid64.msg_qbytes);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
- /* the ipc lock is not held upon failure */
goto out_unlock1;
}
@@ -424,10 +423,11 @@ static int msgctl_down(struct ipc_namesp
err = security_msg_queue_msgctl(msq, cmd);
if (err)
- goto out_unlock0;
+ goto out_unlock1;
switch (cmd) {
case IPC_RMID:
+ ipc_lock_object(&msq->q_perm);
/* freeque unlocks the ipc object and rcu */
freeque(ns, ipcp);
goto out_up;
@@ -435,9 +435,10 @@ static int msgctl_down(struct ipc_namesp
if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
!capable(CAP_SYS_RESOURCE)) {
err = -EPERM;
- goto out_unlock0;
+ goto out_unlock1;
}
+ ipc_lock_object(&msq->q_perm);
err = ipc_update_perm(&msqid64.msg_perm, ipcp);
if (err)
goto out_unlock0;
@@ -456,6 +457,7 @@ static int msgctl_down(struct ipc_namesp
break;
default:
err = -EINVAL;
+ goto out_unlock1;
}
out_unlock0:
_
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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