Subject: + ipcshm-shorten-critical-region-in-shmctl_down.patch added to -mm tree
To: davidlohr.bueso@xxxxxx,manfred@xxxxxxxxxxxxxxxx,riel@xxxxxxxxxx,sedat.dilek@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 16 Jul 2013 15:51:44 -0700
The patch titled
Subject: ipc,shm: shorten critical region in shmctl_down
has been added to the -mm tree. Its filename is
ipcshm-shorten-critical-region-in-shmctl_down.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipcshm-shorten-critical-region-in-shmctl_down.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipcshm-shorten-critical-region-in-shmctl_down.patch
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From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Subject: ipc,shm: shorten critical region in shmctl_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>
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>
---
ipc/shm.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN ipc/shm.c~ipcshm-shorten-critical-region-in-shmctl_down ipc/shm.c
--- a/ipc/shm.c~ipcshm-shorten-critical-region-in-shmctl_down
+++ a/ipc/shm.c
@@ -780,11 +780,10 @@ 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;
}
@@ -792,14 +791,16 @@ 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;
@@ -807,6 +808,7 @@ static int shmctl_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
ipcshm-introduce-lockless-functions-to-obtain-the-ipc-object.patch
ipcshm-shorten-critical-region-in-shmctl_down.patch
ipc-drop-ipcctl_pre_down.patch
ipc-drop-ipcctl_pre_down-fix.patch
ipcshm-introduce-shmctl_nolock.patch
ipcshm-make-shmctl_nolock-lockless.patch
ipcshm-shorten-critical-region-for-shmctl.patch
ipcshm-cleanup-do_shmat-pasta.patch
ipcshm-shorten-critical-region-for-shmat.patch
ipc-rename-ids-rw_mutex.patch
ipcmsg-drop-msg_unlock.patch
ipc-document-general-ipc-locking-scheme.patch
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