| From a5001a0d9768568de5d613c3b3a5b9c7721299da Mon Sep 17 00:00:00 2001 |
| From: Davidlohr Bueso <davidlohr.bueso@hp.com> |
| Date: Mon, 8 Jul 2013 16:01:15 -0700 |
| Subject: ipc,msg: introduce lockless functions to obtain the ipc object |
| |
| From: Davidlohr Bueso <davidlohr.bueso@hp.com> |
| |
| commit a5001a0d9768568de5d613c3b3a5b9c7721299da upstream. |
| |
| Add msq_obtain_object() and msq_obtain_object_check(), which will allow |
| us to get the ipc object without acquiring the lock. Just as with |
| semaphores, these functions are basically wrappers around |
| ipc_obtain_object*(). |
| |
| 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> |
| |
| --- |
| ipc/msg.c | 21 +++++++++++++++++++++ |
| 1 file changed, 21 insertions(+) |
| |
| --- a/ipc/msg.c |
| +++ b/ipc/msg.c |
| @@ -166,6 +166,27 @@ static inline struct msg_queue *msg_lock |
| return container_of(ipcp, struct msg_queue, q_perm); |
| } |
| |
| +static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id) |
| +{ |
| + struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id); |
| + |
| + if (IS_ERR(ipcp)) |
| + return ERR_CAST(ipcp); |
| + |
| + return container_of(ipcp, struct msg_queue, q_perm); |
| +} |
| + |
| +static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, |
| + int id) |
| +{ |
| + struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); |
| + |
| + if (IS_ERR(ipcp)) |
| + return ERR_CAST(ipcp); |
| + |
| + return container_of(ipcp, struct msg_queue, q_perm); |
| +} |
| + |
| static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) |
| { |
| ipc_rmid(&msg_ids(ns), &s->q_perm); |