From 3f9b1a883c61bf15c2dd623bf331a7e84fd0d515 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon, 16 Nov 2009 12:45:14 +0100
Subject: [PATCH] --- yaml --- r: 169625 b: refs/heads/master c:
 559fdc3c1b624edb1933a875022fe7e27934d11c h: refs/heads/master i:   169623:
 4081ef3a953c6011732447797daea2aac4621086 v: v3

---
 [refs]                           |  2 +-
 trunk/include/linux/perf_event.h |  1 -
 trunk/kernel/perf_event.c        | 21 +++++++++++----------
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/[refs] b/[refs]
index a6e2e0d45029..7eae449faa73 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7255fe2a42c612f2b8fe4c347f0a5f0c97d85a46
+refs/heads/master: 559fdc3c1b624edb1933a875022fe7e27934d11c
diff --git a/trunk/include/linux/perf_event.h b/trunk/include/linux/perf_event.h
index df4e73e33774..7f87563c8485 100644
--- a/trunk/include/linux/perf_event.h
+++ b/trunk/include/linux/perf_event.h
@@ -714,7 +714,6 @@ struct perf_output_handle {
 	int				nmi;
 	int				sample;
 	int				locked;
-	unsigned long			flags;
 };
 
 #ifdef CONFIG_PERF_EVENTS
diff --git a/trunk/kernel/perf_event.c b/trunk/kernel/perf_event.c
index 6f4ed3b4cd73..3256e36ad251 100644
--- a/trunk/kernel/perf_event.c
+++ b/trunk/kernel/perf_event.c
@@ -2674,20 +2674,21 @@ static void perf_output_wakeup(struct perf_output_handle *handle)
 static void perf_output_lock(struct perf_output_handle *handle)
 {
 	struct perf_mmap_data *data = handle->data;
-	int cpu;
+	int cur, cpu = get_cpu();
 
 	handle->locked = 0;
 
-	local_irq_save(handle->flags);
-	cpu = smp_processor_id();
-
-	if (in_nmi() && atomic_read(&data->lock) == cpu)
-		return;
+	for (;;) {
+		cur = atomic_cmpxchg(&data->lock, -1, cpu);
+		if (cur == -1) {
+			handle->locked = 1;
+			break;
+		}
+		if (cur == cpu)
+			break;
 
-	while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
 		cpu_relax();
-
-	handle->locked = 1;
+	}
 }
 
 static void perf_output_unlock(struct perf_output_handle *handle)
@@ -2733,7 +2734,7 @@ static void perf_output_unlock(struct perf_output_handle *handle)
 	if (atomic_xchg(&data->wakeup, 0))
 		perf_output_wakeup(handle);
 out:
-	local_irq_restore(handle->flags);
+	put_cpu();
 }
 
 void perf_output_copy(struct perf_output_handle *handle,