Re: [PATCH bpf-next 0/6] bpftool: Allow to select sections and filter probes

On Tue, Feb 18, 2020 at 11:02 AM Michal Rostecki mrostecki@opensuse.org wrote:

This patch series extend the "bpftool feature" subcommand with the new positional arguments:

• "section", which allows to select a specific section of probes (i.e. "system_config", "program_types", "map_types");
• "filter_in", which allows to select only probes which matches the given regex pattern;
• "filter_out", which allows to filter out probes which do not match the given regex pattern.

The main motivation behind those changes is ability the fact that some probes (for example those related to "trace" or "write_user" helpers) emit dmesg messages which might be confusing for people who are running on production environments. For details see the Cilium issue[0].

[0] https://github.com/cilium/cilium/issues/10048

The motivation is clear, but I think the users shouldn't be made aware of such implementation details. I think instead of filter_in/out it's better to do 'full or safe' mode of probing. By default it can do all the probing that doesn't cause extra dmesgs and in 'full' mode it can probe everything.