tools: bpftool: warn about risky prog array updates
authorJakub Kicinski <jakub.kicinski@netronome.com>
Mon, 28 Jan 2019 18:29:15 +0000 (10:29 -0800)
committerDaniel Borkmann <daniel@iogearbox.net>
Mon, 28 Jan 2019 23:27:38 +0000 (00:27 +0100)
commitd76198b0bc5a67c14c5209bac82481399a3387da
tree8fdf782d63e20ec1aa8036cd83ad77a7aabb97f5
parentcdd7b40642582f5130ea5ec20432175a70c8933e
tools: bpftool: warn about risky prog array updates

When prog array is updated with bpftool users often refer
to the map via the ID.  Unfortunately, that's likely
to lead to confusion because prog arrays get flushed when
the last user reference is gone.  If there is no other
reference bpftool will create one, update successfully
just to close the map again and have it flushed.

Warn about this case in non-JSON mode.

If the problem continues causing confusion we can remove
the support for referring to a map by ID for prog array
update completely.  For now it seems like the potential
inconvenience to users who know what they're doing outweighs
the benefit.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
tools/bpf/bpftool/map.c