From 53d1ac83407b1e56582710c493163b49fd071f45 Mon Sep 17 00:00:00 2001
From: Nick Piggin <npiggin@suse.de>
Date: Tue, 15 Dec 2009 16:47:28 -0800
Subject: [PATCH] --- yaml --- r: 176690 b: refs/heads/master c:
 bf17bb717759d50a2733a7a8157a7c4a25d93abc h: refs/heads/master v: v3

---
 [refs]          |  2 +-
 trunk/ipc/sem.c | 26 ++++++++++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/[refs] b/[refs]
index f157ece44a6f..50e7e0492b21 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7d6feeb287c61aafa88f06345387b1188edf4b86
+refs/heads/master: bf17bb717759d50a2733a7a8157a7c4a25d93abc
diff --git a/trunk/ipc/sem.c b/trunk/ipc/sem.c
index 2f2a47959576..cb0070ecf5bf 100644
--- a/trunk/ipc/sem.c
+++ b/trunk/ipc/sem.c
@@ -962,17 +962,31 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
 	return 0;
 }
 
-static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
+static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
 {
-	struct sem_undo *walk;
+	struct sem_undo *un;
 
-	list_for_each_entry_rcu(walk, &ulp->list_proc, list_proc) {
-		if (walk->semid == semid)
-			return walk;
+	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
+		if (un->semid == semid)
+			return un;
 	}
 	return NULL;
 }
 
+static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
+{
+	struct sem_undo *un;
+
+  	assert_spin_locked(&ulp->lock);
+
+	un = __lookup_undo(ulp, semid);
+	if (un) {
+		list_del_rcu(&un->list_proc);
+		list_add_rcu(&un->list_proc, &ulp->list_proc);
+	}
+	return un;
+}
+
 /**
  * find_alloc_undo - Lookup (and if not present create) undo array
  * @ns: namespace
@@ -1308,7 +1322,7 @@ void exit_sem(struct task_struct *tsk)
 		if (IS_ERR(sma))
 			continue;
 
-		un = lookup_undo(ulp, semid);
+		un = __lookup_undo(ulp, semid);
 		if (un == NULL) {
 			/* exit_sem raced with IPC_RMID+semget() that created
 			 * exactly the same semid. Nothing to do.