perf_counter: kerneltop: simplify data_head read
Now that the kernel side changed, match up again.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.327144324@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c
index fda1438..2779c57 100644
--- a/Documentation/perf_counter/kerneltop.c
+++ b/Documentation/perf_counter/kerneltop.c
@@ -1125,22 +1125,10 @@
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;
}