Patch "tracing/filter: Do not WARN on operand count going below zero" has been added to the 4.1-stable tree

[<gregkh@linuxfoundation.org>]

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

    tracing/filter: Do not WARN on operand count going below zero

to the 4.1-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-filter-do-not-warn-on-operand-count-going-below-zero.patch
and it can be found in the queue-4.1 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 b4875bbe7e68f139bd3383828ae8e994a0df6d28 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Thu, 25 Jun 2015 18:02:29 -0400
Subject: tracing/filter: Do not WARN on operand count going below zero

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

commit b4875bbe7e68f139bd3383828ae8e994a0df6d28 upstream.

When testing the fix for the trace filter, I could not come up with
a scenario where the operand count goes below zero, so I added a
WARN_ON_ONCE(cnt < 0) to the logic. But there is legitimate case
that it can happen (although the filter would be wrong).

 # echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter

That is, a single operation without any operands will hit the path
where the WARN_ON_ONCE() can trigger. Although this is harmless,
and the filter is reported as a error. But instead of spitting out
a warning to the kernel dmesg, just fail nicely and report it via
the proper channels.

Link: http://lkml.kernel.org/r/558C6082.90608@oracle.com

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace_events_filter.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1385,7 +1385,9 @@ static int check_preds(struct filter_par
 		if (elt->op != OP_NOT)
 			cnt--;
 		n_normal_preds++;
-		WARN_ON_ONCE(cnt < 0);
+		/* all ops should have operands */
+		if (cnt < 0)
+			break;
 	}
 
 	if (cnt != 1 || !n_normal_preds || n_logical_preds >= n_normal_preds) {


Patches currently in stable-queue which might be from rostedt@goodmis.org are

queue-4.1/tracing-have-branch-tracer-use-recursive-field-of-task-struct.patch
queue-4.1/tracing-fix-sample-output-of-dynamic-arrays.patch
queue-4.1/tracing-filter-do-not-allow-infix-to-exceed-end-of-string.patch
queue-4.1/tracing-fix-typo-from-static-inlin-to-static-inline.patch
queue-4.1/tracing-filter-do-not-warn-on-operand-count-going-below-zero.patch