libtracefs: Return negative number when tracefs_filter_string_append() fails

If the field passed into tracefs_filter_string_append() does not match a
field of the event, or if the value is not proper, it fails to append the
filter, but still returns 0 as it was successful.

Return -1 if it fails.

Link: https://lore.kernel.org/linux-trace-devel/20220722161732.0c5d7023@gandalf.local.home

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
1 file changed