diff options
| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-07-08 16:01:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-09 10:33:27 -0700 |
| commit | 7b4cc5d8411bd4e9d61d8714f53859740cf830c2 (patch) | |
| tree | b95f3b875a5f4c927b0f27cc3c7ddcba5cc8e1e8 /ipc/sem.c | |
| parent | cf9d5d78d05bca96df7618dfc3a5ee4414dcae58 (diff) | |
ipc: move locking out of ipcctl_pre_down_nolock
This function currently acquires both the rw_mutex and the rcu lock on
successful lookups, leaving the callers to explicitly unlock them,
creating another two level locking situation.
Make the callers (including those that still use ipcctl_pre_down())
explicitly lock and unlock the rwsem and rcu lock.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 92ec6c69bab..b4b892b5c5f 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1289,39 +1289,44 @@ static int semctl_down(struct ipc_namespace *ns, int semid, return -EFAULT; } + down_write(&sem_ids(ns).rw_mutex); + rcu_read_lock(); + ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd, &semid64.sem_perm, 0); - if (IS_ERR(ipcp)) - return PTR_ERR(ipcp); + if (IS_ERR(ipcp)) { + err = PTR_ERR(ipcp); + /* the ipc lock is not held upon failure */ + goto out_unlock1; + } sma = container_of(ipcp, struct sem_array, sem_perm); err = security_sem_semctl(sma, cmd); - if (err) { - rcu_read_unlock(); - goto out_up; - } + if (err) + goto out_unlock1; - switch(cmd){ + switch (cmd) { case IPC_RMID: sem_lock(sma, NULL, -1); + /* freeary unlocks the ipc object and rcu */ freeary(ns, ipcp); goto out_up; case IPC_SET: sem_lock(sma, NULL, -1); err = ipc_update_perm(&semid64.sem_perm, ipcp); if (err) - goto out_unlock; + goto out_unlock0; sma->sem_ctime = get_seconds(); break; default: - rcu_read_unlock(); err = -EINVAL; - goto out_up; + goto out_unlock1; } -out_unlock: +out_unlock0: sem_unlock(sma, -1); +out_unlock1: rcu_read_unlock(); out_up: up_write(&sem_ids(ns).rw_mutex); |