[PATCH 3/9] perf_counter: kerneltop: simplify data_head read

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

[-- Attachment #1: kerneltop-new-mmap.patch --]
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Now that the kernel side changed, match up again.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 Documentation/perf_counter/kerneltop.c |   14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

Index: linux-2.6/Documentation/perf_counter/kerneltop.c
===================================================================
--- linux-2.6.orig/Documentation/perf_counter/kerneltop.c
+++ linux-2.6/Documentation/perf_counter/kerneltop.c
@@ -1125,22 +1125,10 @@ struct mmap_data {
 static unsigned int mmap_read_head(struct mmap_data *md)
 {
 	struct perf_counter_mmap_page *pc = md->base;
-	unsigned int seq, head;
-
-repeat:
-	rmb();
-	seq = pc->lock;
-
-	if (unlikely(seq & 1)) {
-		cpu_relax();
-		goto repeat;
-	}
+	int head;
 
 	head = pc->data_head;
-
 	rmb();
-	if (pc->lock != seq)
-		goto repeat;
 
 	return head;
 }

--