From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 2 Sep 2009 14:56:15 +0000 (-0400)
Subject: ring-buffer: do not swap buffers during a commit
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=98277991a99734f3a31d638afb47d4484ac73e43;p=linux-beck.git

ring-buffer: do not swap buffers during a commit

If a commit is taking place on a CPU ring buffer, do not allow it to
be swapped. Return -EBUSY when this is detected instead.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 79d6012bb1f1..2878bd43a59c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3519,16 +3519,23 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 	atomic_inc(&cpu_buffer_a->record_disabled);
 	atomic_inc(&cpu_buffer_b->record_disabled);
 
+	ret = -EBUSY;
+	if (local_read(&cpu_buffer_a->committing))
+		goto out_dec;
+	if (local_read(&cpu_buffer_b->committing))
+		goto out_dec;
+
 	buffer_a->buffers[cpu] = cpu_buffer_b;
 	buffer_b->buffers[cpu] = cpu_buffer_a;
 
 	cpu_buffer_b->buffer = buffer_a;
 	cpu_buffer_a->buffer = buffer_b;
 
+	ret = 0;
+
+out_dec:
 	atomic_dec(&cpu_buffer_a->record_disabled);
 	atomic_dec(&cpu_buffer_b->record_disabled);
-
-	ret = 0;
 out:
 	return ret;
 }