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| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-09-11 14:26:16 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:47 -0700 |
| commit | b3b7b427fd385e92ce2ea8a847ec977724dc9669 (patch) | |
| tree | 290f864a6a4ac5ca67bbdd712e599457278172e4 | |
| parent | 1b2ad167481aed32347ef7726d14bb2b9f63c4c9 (diff) | |
| download | lwn-b3b7b427fd385e92ce2ea8a847ec977724dc9669.tar.gz lwn-b3b7b427fd385e92ce2ea8a847ec977724dc9669.zip | |
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>
| -rw-r--r-- | ipc/shm.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 5f106b4800c3..9020ac8eb7f5 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: |