diff options
| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-07-08 16:01:17 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:46 -0700 |
| commit | 8398fe18b48b6e4ac671898cd9b7327954b4ba5f (patch) | |
| tree | 6d86ecca02250029e4ef65438231bac0150b1e34 /ipc | |
| parent | 107b413cd33374f8eb3a0075d0237e1076e0a752 (diff) | |
ipc,msg: shorten critical region in msgsnd
commit 3dd1f784ed6603d7ab1043e51e6371235edf2313 upstream.
do_msgsnd() is another function that does too many things with the ipc
object lock acquired. Take it only when needed when actually updating
msq.
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>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'ipc')
| -rw-r--r-- | ipc/msg.c | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index c0fe57cc39f..15050532c78 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -698,10 +698,11 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, msg->m_type = mtype; msg->m_ts = msgsz; - msq = msg_lock_check(ns, msqid); + rcu_read_lock(); + msq = msq_obtain_object_check(ns, msqid); if (IS_ERR(msq)) { err = PTR_ERR(msq); - goto out_free; + goto out_unlock1; } for (;;) { @@ -709,11 +710,11 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, err = -EACCES; if (ipcperms(ns, &msq->q_perm, S_IWUGO)) - goto out_unlock_free; + goto out_unlock1; err = security_msg_queue_msgsnd(msq, msg, msgflg); if (err) - goto out_unlock_free; + goto out_unlock1; if (msgsz + msq->q_cbytes <= msq->q_qbytes && 1 + msq->q_qnum <= msq->q_qbytes) { @@ -723,32 +724,41 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, /* queue full, wait: */ if (msgflg & IPC_NOWAIT) { err = -EAGAIN; - goto out_unlock_free; + goto out_unlock1; } + + ipc_lock_object(&msq->q_perm); ss_add(msq, &s); if (!ipc_rcu_getref(msq)) { err = -EIDRM; - goto out_unlock_free; + goto out_unlock0; } - msg_unlock(msq); + ipc_unlock_object(&msq->q_perm); + rcu_read_unlock(); schedule(); - ipc_lock_by_ptr(&msq->q_perm); + rcu_read_lock(); + ipc_lock_object(&msq->q_perm); + ipc_rcu_putref(msq); if (msq->q_perm.deleted) { err = -EIDRM; - goto out_unlock_free; + goto out_unlock0; } + ss_del(&s); if (signal_pending(current)) { err = -ERESTARTNOHAND; - goto out_unlock_free; + goto out_unlock0; } + + ipc_unlock_object(&msq->q_perm); } + ipc_lock_object(&msq->q_perm); msq->q_lspid = task_tgid_vnr(current); msq->q_stime = get_seconds(); @@ -764,9 +774,10 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, err = 0; msg = NULL; -out_unlock_free: - msg_unlock(msq); -out_free: +out_unlock0: + ipc_unlock_object(&msq->q_perm); +out_unlock1: + rcu_read_unlock(); if (msg != NULL) free_msg(msg); return err; |