Patch "tracing: Erase irqsoff trace with empty write" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    tracing: Erase irqsoff trace with empty write

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-erase-irqsoff-trace-with-empty-write.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8dd33bcb7050dd6f8c1432732f930932c9d3a33e Mon Sep 17 00:00:00 2001
From: Bo Yan <byan@nvidia.com>
Date: Mon, 18 Sep 2017 10:03:35 -0700
Subject: tracing: Erase irqsoff trace with empty write

From: Bo Yan <byan@nvidia.com>

commit 8dd33bcb7050dd6f8c1432732f930932c9d3a33e upstream.

One convenient way to erase trace is "echo > trace". However, this
is currently broken if the current tracer is irqsoff tracer. This
is because irqsoff tracer use max_buffer as the default trace
buffer.

Set the max_buffer as the one to be cleared when it's the trace
buffer currently in use.

Link: http://lkml.kernel.org/r/1505754215-29411-1-git-send-email-byan@nvidia.com

Cc: <mingo@redhat.com>
Fixes: 4acd4d00f ("tracing: give easy way to clear trace buffer")
Signed-off-by: Bo Yan <byan@nvidia.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3168,11 +3168,17 @@ static int tracing_open(struct inode *in
 	/* If this file was open for write, then erase contents */
 	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 		int cpu = tracing_get_cpu(inode);
+		struct trace_buffer *trace_buf = &tr->trace_buffer;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+		if (tr->current_trace->print_max)
+			trace_buf = &tr->max_buffer;
+#endif
 
 		if (cpu == RING_BUFFER_ALL_CPUS)
-			tracing_reset_online_cpus(&tr->trace_buffer);
+			tracing_reset_online_cpus(trace_buf);
 		else
-			tracing_reset(&tr->trace_buffer, cpu);
+			tracing_reset(trace_buf, cpu);
 	}
 
 	if (file->f_mode & FMODE_READ) {


Patches currently in stable-queue which might be from byan@nvidia.com are

queue-3.18/tracing-erase-irqsoff-trace-with-empty-write.patch