From 845279972f1736c3463c9cebd1bad92a0a347176 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Mon, 12 May 2008 21:20:58 +0200
Subject: [PATCH] ftrace: return EOF in trace_pipe on change of tracer

Break out of while loop with EOF when the current_trace changes.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/trace/trace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d141fc98f3..2af940433e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2253,6 +2253,9 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 		if (signal_pending(current))
 			return -EINTR;
 
+		if (iter->trace != current_trace)
+			return 0;
+
 		/*
 		 * We block until we read something and tracing is disabled.
 		 * We still block if tracing is disabled, but we have never
-- 
2.39.5