From e5f9ad14b40dc9edda131690d75e310abbee92ad Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Wed, 17 Dec 2008 08:54:56 +0100
Subject: [PATCH] --- yaml --- r: 147166 b: refs/heads/master c:
 7995888fcb0246543ee8027bf2835a250ba8c925 h: refs/heads/master v: v3

---
 [refs]                      |  2 +-
 trunk/kernel/perf_counter.c | 16 +++++++++++++---
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 7a7e40a2d9b8..dcf138eb82cb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8fb9331391af95ca1f4e5c0a0da8120b13cbae01
+refs/heads/master: 7995888fcb0246543ee8027bf2835a250ba8c925
diff --git a/trunk/kernel/perf_counter.c b/trunk/kernel/perf_counter.c
index aab6c123b02c..f8a4d9a5d5d3 100644
--- a/trunk/kernel/perf_counter.c
+++ b/trunk/kernel/perf_counter.c
@@ -367,21 +367,26 @@ counter_sched_in(struct perf_counter *counter,
 	ctx->nr_active++;
 }
 
-static void
+static int
 group_sched_in(struct perf_counter *group_counter,
 	       struct perf_cpu_context *cpuctx,
 	       struct perf_counter_context *ctx,
 	       int cpu)
 {
 	struct perf_counter *counter;
+	int was_group = 0;
 
 	counter_sched_in(group_counter, cpuctx, ctx, cpu);
 
 	/*
 	 * Schedule in siblings as one group (if any):
 	 */
-	list_for_each_entry(counter, &group_counter->sibling_list, list_entry)
+	list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
 		counter_sched_in(counter, cpuctx, ctx, cpu);
+		was_group = 1;
+	}
+
+	return was_group;
 }
 
 /*
@@ -416,7 +421,12 @@ void perf_counter_task_sched_in(struct task_struct *task, int cpu)
 		if (counter->cpu != -1 && counter->cpu != cpu)
 			continue;
 
-		group_sched_in(counter, cpuctx, ctx, cpu);
+		/*
+		 * If we scheduled in a group atomically and
+		 * exclusively, break out:
+		 */
+		if (group_sched_in(counter, cpuctx, ctx, cpu))
+			break;
 	}
 	spin_unlock(&ctx->lock);