[PATCH 5/5] tracing/ftrace: make nop using polling wait for events on pipe

[Frederic Weisbecker <fweisbec@gmail.com>]

Impact: display events when they arrive

Now that the events don't use wake_up() anymore, we need the nop
tracer to poll waiting for events on the pipe. Especially because
nop is useful to look at orphans traces types (traces types that
don't rely on specific tracers) because it doesn't produce traces
itself.

And unlike other tracers that trigger specific traces periodically,
nop triggers no traces by itself that can wake him.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/trace_nop.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c
index 9aa84bd..394f944 100644
--- a/kernel/trace/trace_nop.c
+++ b/kernel/trace/trace_nop.c
@@ -91,6 +91,7 @@ struct tracer nop_trace __read_mostly =
 	.name		= "nop",
 	.init		= nop_trace_init,
 	.reset		= nop_trace_reset,
+	.wait_pipe	= poll_wait_pipe,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest	= trace_selftest_startup_nop,
 #endif
-- 
1.6.1