| 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 |
| @@ -1342,7 +1342,9 @@ static int check_preds(struct filter_par |
| continue; |
| } |
| 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) { |
