Merge tag 'v3.13-rc4' into next

Synchronize with mainline to bring in the new keycode definitions and
new hwmon API.

1 files changed, 22 insertions, 9 deletions

diff --git a/ipc/util.c b/ipc/util.c
index fdb8ae74077..3ae17a4ace5 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -17,12 +17,27 @@
  *            Pavel Emelianov <xemul@openvz.org>
  *
  * General sysv ipc locking scheme:
- *  when doing ipc id lookups, take the ids->rwsem
- *      rcu_read_lock()
- *          obtain the ipc object (kern_ipc_perm)
- *          perform security, capabilities, auditing and permission checks, etc.
- *          acquire the ipc lock (kern_ipc_perm.lock) throught ipc_lock_object()
- *             perform data updates (ie: SET, RMID, LOCK/UNLOCK commands)
+ *	rcu_read_lock()
+ *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
+ *	    tree.
+ *	    - perform initial checks (capabilities, auditing and permission,
+ *	      etc).
+ *	    - perform read-only operations, such as STAT, INFO commands.
+ *	      acquire the ipc lock (kern_ipc_perm.lock) through
+ *	      ipc_lock_object()
+ *		- perform data updates, such as SET, RMID commands and
+ *		  mechanism-specific operations (semop/semtimedop,
+ *		  msgsnd/msgrcv, shmat/shmdt).
+ *	    drop the ipc lock, through ipc_unlock_object().
+ *	rcu_read_unlock()
+ *
+ *  The ids->rwsem must be taken when:
+ *	- creating, removing and iterating the existing entries in ipc
+ *	  identifier sets.
+ *	- iterating through files under /proc/sysvipc/
+ *
+ *  Note that sems have a special fast path that avoids kern_ipc_perm.lock -
+ *  see sem_lock().
  */
 
 #include <linux/mm.h>
@@ -75,10 +90,8 @@ static int ipc_memory_callback(struct notifier_block *self,
 		 * In order not to keep the lock on the hotplug memory chain
 		 * for too long, queue a work item that will, when waken up,
 		 * activate the ipcns notification chain.
-		 * No need to keep several ipc work items on the queue.
 		 */
-		if (!work_pending(&ipc_memory_wq))
-			schedule_work(&ipc_memory_wq);
+		schedule_work(&ipc_memory_wq);
 		break;
 	case MEM_GOING_ONLINE:
 	case MEM_GOING_OFFLINE: