From: Guru Anbalagane <guru.anbalagane@oracle.com>
Date: Tue, 13 Sep 2011 19:10:13 +0000 (-0700)
Subject: Revert "ipc semaphores: order wakeups based on waiter CPU"
X-Git-Tag: v2.6.39-400.9.0~913
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=6c92631b5aabae8bbc98e5090cd85dde4ee72710;p=users%2Fjedix%2Flinux-maple.git

Revert "ipc semaphores: order wakeups based on waiter CPU"

This reverts commit 8102e1ff9d667661b581209323faaf7a84f0f528.
---

diff --git a/include/linux/sem.h b/include/linux/sem.h
index 15da841d11614..5a97a370c71de 100644
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -106,7 +106,6 @@ struct sem_array {
 struct sem_queue {
 	struct list_head	list;	 /* queue of pending operations */
 	struct task_struct	*sleeper; /* this process */
-	unsigned long		sleep_cpu;
 	struct sem_undo		*undo;	 /* undo structure */
 	int    			pid;	 /* process id of requesting process */
 	int    			status;	 /* completion status of operation */
diff --git a/ipc/sem.c b/ipc/sem.c
index d34316d8a9244..4643652be3f53 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -572,25 +572,6 @@ static void wake_up_sem_queue_do(struct list_head *pt)
 		preempt_enable();
 }
 
-/*
- * sorting helper for struct sem_queues in a list.  This is used to
- * sort by the CPU they are likely to be on when waking them.
- */
-int list_comp(void *priv, struct list_head *a, struct list_head *b)
-{
-	struct sem_queue *qa;
-	struct sem_queue *qb;
-
-	qa = list_entry(a, struct sem_queue, list);
-	qb = list_entry(b, struct sem_queue, list);
-
-	if (qa->sleep_cpu < qb->sleep_cpu)
-		return -1;
-	if (qa->sleep_cpu > qb->sleep_cpu)
-		return 1;
-	return 0;
-}
-
 /**
  * update_queue(sma, semnum): Look for tasks that can be completed.
  * @sma: semaphore array.
@@ -610,7 +591,6 @@ static int update_queue(struct sem_array *sma, struct list_head *pt,
 	struct sem_queue *q;
 	LIST_HEAD(new_pending);
 	LIST_HEAD(work_list);
-	LIST_HEAD(wake_list);
 	int semop_completed = 0;
 
 	/*
@@ -650,24 +630,13 @@ again:
 		if (!error)
 			semop_completed = 1;
 
-		if (error)
-			wake_up_sem_queue_prepare(pt, q, error);
-		else
-			list_add_tail(&q->list, &wake_list);
+		wake_up_sem_queue_prepare(pt, q, error);
 
 		if (!list_empty(&new_pending)) {
 			list_splice_init(&new_pending, &work_list);
 			goto again;
 		}
 	}
-
-	list_sort(NULL, &wake_list, list_comp);
-	while (!list_empty(&wake_list)) {
-		q = list_entry(wake_list.next, struct sem_queue, list);
-		list_del_init(&q->list);
-		wake_up_sem_queue_prepare(pt, q, 0);
-	}
-
 	return semop_completed;
 }
 
@@ -1582,12 +1551,6 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
 	queue.alter = alter;
 	queue.status = -EINTR;
 	queue.sleeper = current;
-
-	/*
-	 * the sleep_cpu number allows sorting by the CPU we expect
-	 * their runqueue entry to be on..hopefully faster for waking up
-	 */
-	queue.sleep_cpu = my_cpu_offset;
 	current->state = TASK_INTERRUPTIBLE;
 
 	/*