ipc/sem: separate wait-for-zero and alter tasks into seperate queues

Introduce separate queues for operations that do not modify the
semaphore values.  Advantages:

 - Simpler logic in check_restart().
 - Faster update_queue(): Right now, all wait-for-zero operations are
   always tested, even if the semaphore value is not 0.
 - wait-for-zero gets again priority, as in linux <=3.0.9

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/sem.h b/include/linux/sem.h
index 53d42650b193..55e17f68d256 100644
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -15,7 +15,10 @@ struct sem_array {
         time_t                  sem_otime;      /* last semop time */
         time_t                  sem_ctime;      /* last change time */
         struct sem              *sem_base;      /* ptr to first semaphore in array */
-        struct list_head        sem_pending;    /* pending operations to be processed */
+        struct list_head        pending_alter;  /* pending operations */
+                                                /* that alter the array */
+        struct list_head        pending_const;  /* pending complex operations */
+                                                /* that do not alter semvals */
         struct list_head        list_id;        /* undo requests on this array */
         int                     sem_nsems;      /* no. of semaphores in array */
         int                     complex_count;  /* pending complex operations */