This is a note to let you know that I've just added the patch titled
ipc,shm: shorten critical region in shmctl_down
to the 3.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipc-shm-shorten-critical-region-in-shmctl_down.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 79ccf0f8c8e04e8b9eda6645ba0f63b0915a3075 Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Date: Wed, 11 Sep 2013 14:26:16 -0700
Subject: ipc,shm: shorten critical region in shmctl_down
From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
commit 79ccf0f8c8e04e8b9eda6645ba0f63b0915a3075 upstream.
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>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
ipc/shm.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -787,11 +787,10 @@ static int shmctl_down(struct ipc_namesp
down_write(&shm_ids(ns).rw_mutex);
rcu_read_lock();
- ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
- &shmid64.shm_perm, 0);
+ ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
+ &shmid64.shm_perm, 0);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
- /* the ipc lock is not held upon failure */
goto out_unlock1;
}
@@ -799,14 +798,16 @@ static int shmctl_down(struct ipc_namesp
err = security_shm_shmctl(shp, cmd);
if (err)
- goto out_unlock0;
+ goto out_unlock1;
switch (cmd) {
case IPC_RMID:
+ ipc_lock_object(&shp->shm_perm);
/* do_shm_rmid unlocks the ipc object and rcu */
do_shm_rmid(ns, ipcp);
goto out_up;
case IPC_SET:
+ ipc_lock_object(&shp->shm_perm);
err = ipc_update_perm(&shmid64.shm_perm, ipcp);
if (err)
goto out_unlock0;
@@ -814,6 +815,7 @@ static int shmctl_down(struct ipc_namesp
break;
default:
err = -EINVAL;
+ goto out_unlock1;
}
out_unlock0:
Patches currently in stable-queue which might be from davidlohr.bueso@xxxxxx are
queue-3.11/ipc-shm-shorten-critical-region-in-shmctl_down.patch
queue-3.11/ipc-shm-introduce-lockless-functions-to-obtain-the-ipc-object.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmat.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmctl.patch
queue-3.11/ipc-shm-introduce-shmctl_nolock.patch
queue-3.11/ipc-drop-ipcctl_pre_down.patch
queue-3.11/ipc-shm-cleanup-do_shmat-pasta.patch
queue-3.11/ipc-shm-make-shmctl_nolock-lockless.patch
--
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