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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2015-06-25 18:02:29 -0400 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2015-10-22 09:20:06 +0800 |
| commit | 7ebabd77613ddc5b1841c788085c5ac8c6b2cd85 (patch) | |
| tree | e39de8a4ecf033b01f21d27eca26a68bddc1d2e1 | |
| parent | 800e58ae21796a472f39cd6d0601c87b297409af (diff) | |
| download | lwn-7ebabd77613ddc5b1841c788085c5ac8c6b2cd85.tar.gz lwn-7ebabd77613ddc5b1841c788085c5ac8c6b2cd85.zip | |
tracing/filter: Do not WARN on operand count going below zero
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: Zefan Li <lizefan@huawei.com>
| -rw-r--r-- | kernel/trace/trace_events_filter.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 3b04aec58700..ae6c5722efb9 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1372,7 +1372,9 @@ static int check_preds(struct filter_parse_state *ps) } 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) { |