From 230a3c31ccdb5b16f8a08502ebb61d4207da460f Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon, 6 Apr 2009 11:44:59 +0200
Subject: [PATCH] --- yaml --- r: 147323 b: refs/heads/master c:
 a2e87d06ddbe6e6fdb8d6d2e5e985efe4efb07dd h: refs/heads/master i:   147321:
 07a31f67fa7829ca15ceff611ae88bd9b85f8dc1   147319:
 f08e71827fc794be8adae71560e446c11b525518 v: v3

---
 [refs]                             |  2 +-
 trunk/include/linux/perf_counter.h | 24 ++++++++++--------------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/[refs] b/[refs]
index 6f812f546a6d..c796cab4aa44 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 92f22a3865abe87eea2609a6f8e5be5123f7ce4f
+refs/heads/master: a2e87d06ddbe6e6fdb8d6d2e5e985efe4efb07dd
diff --git a/trunk/include/linux/perf_counter.h b/trunk/include/linux/perf_counter.h
index f2b914de3f0c..e22ab47a2f41 100644
--- a/trunk/include/linux/perf_counter.h
+++ b/trunk/include/linux/perf_counter.h
@@ -170,22 +170,18 @@ struct perf_counter_mmap_page {
 	 *   u32 seq;
 	 *   s64 count;
 	 *
-	 * again:
-	 *   seq = pc->lock;
-	 *   if (unlikely(seq & 1)) {
-	 *     cpu_relax();
-	 *     goto again;
-	 *   }
+	 *   do {
+	 *     seq = pc->lock;
 	 *
-	 *   if (pc->index) {
-	 *     count = pmc_read(pc->index - 1);
-	 *     count += pc->offset;
-	 *   } else
-	 *     goto regular_read;
+	 *     barrier()
+	 *     if (pc->index) {
+	 *       count = pmc_read(pc->index - 1);
+	 *       count += pc->offset;
+	 *     } else
+	 *       goto regular_read;
 	 *
-	 *   barrier();
-	 *   if (pc->lock != seq)
-	 *     goto again;
+	 *     barrier();
+	 *   } while (pc->lock != seq);
 	 *
 	 * NOTE: for obvious reason this only works on self-monitoring
 	 *       processes.