ftrace: trace_pipe implement NONBLOCK
This patch implements "NONBLOCK" for trace_pipe. If the trace_pipe is opened
with O_NONBLOCK, then the trace_pipe read will not block when buffer is empty.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2af9404..3b4eaf3 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2233,6 +2233,10 @@
start = 0;
while (trace_empty(iter)) {
+
+ if ((filp->f_flags & O_NONBLOCK))
+ return -EAGAIN;
+
/*
* This is a make-shift waitqueue. The reason we don't use
* an actual wait queue is because: