From 2dc8f09571a61d9cb3dc47bba6608689dfe15d16 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 12 May 2008 21:20:58 +0200 Subject: [PATCH] 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 Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/trace/trace.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2af940433e96..3b4eaf36ed5d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2233,6 +2233,10 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 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: