On 5/28/24 5:31 PM, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
>
> When a filter is in place, the stack trace for the events that are
> printed by the filter should also be printed. Stack traces for events
> that are filtered out, should also be filtered out. But there was a bug
> in the logic that checked if the last event was printed or not to know
> to print the stack, and that is, the stack from the printed event was
> considered a printed event itself. So a stack trace coming from another
> event could be considered "printed" if two stacks came back to back
> (which can happen because of interrupts.
>
> Note, this does mean that logic should be added to test for interrupts.
> But that's another story.
>
> Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
> Fixes: 82ed4a937 ("trace-cmd library: Add filtering logic for iterating events")
> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Seems to work as intended now. Thanks!
Tested-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> lib/trace-cmd/trace-filter.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/lib/trace-cmd/trace-filter.c b/lib/trace-cmd/trace-filter.c
> index 1c8c07fc..99423223 100644
> --- a/lib/trace-cmd/trace-filter.c
> +++ b/lib/trace-cmd/trace-filter.c
> @@ -47,6 +47,7 @@ static bool test_stacktraces(struct tracecmd_filter *filter, struct tep_record *
> __hidden enum tracecmd_filters tracecmd_filter_match(struct tracecmd_filter *filter,
> struct tep_record *record)
> {
> + bool is_stack = false;
> bool found = false;
> int ret;
> int i;
> @@ -94,6 +95,8 @@ __hidden enum tracecmd_filters tracecmd_filter_match(struct tracecmd_filter *fil
> /* If this is a stack trace and the last event was printed continue */
> if (!test_stacktraces(filter, record))
> return TRACECMD_FILTER_MISS;
> +
> + is_stack = true;
> }
>
> found = false;
> @@ -110,7 +113,7 @@ __hidden enum tracecmd_filters tracecmd_filter_match(struct tracecmd_filter *fil
> }
>
> if (filter->last_printed)
> - filter->last_printed[record->cpu] = !found;
> + filter->last_printed[record->cpu] = !is_stack && !found;
>
> return found ? TRACECMD_FILTER_MISS : TRACECMD_FILTER_MATCH;
> }
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