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>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d141fc98f3a8..2af940433e96 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