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authorDavidlohr Bueso <davidlohr.bueso@hp.com>2013-09-11 14:26:16 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-10-18 07:45:47 -0700
commitb3b7b427fd385e92ce2ea8a847ec977724dc9669 (patch)
tree290f864a6a4ac5ca67bbdd712e599457278172e4 /ipc
parent1b2ad167481aed32347ef7726d14bb2b9f63c4c9 (diff)
downloadlinaro-lsk-b3b7b427fd385e92ce2ea8a847ec977724dc9669.tar.gz
ipc,shm: shorten critical region in shmctl_down
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@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/shm.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 5f106b4800c..9020ac8eb7f 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -780,11 +780,10 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
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_namespace *ns, int shmid, int cmd,
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_namespace *ns, int shmid, int cmd,
break;
default:
err = -EINVAL;
+ goto out_unlock1;
}
out_unlock0: