Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> writes: > On Thu, Oct 24, 2019 at 6:11 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: >> >> From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> >> >> With the functions added in previous commits that can automatically pin >> maps based on their 'pinning' setting, we can support auto-pinning of maps >> by the simple setting of an option to bpf_object__open. >> >> Since auto-pinning only does something if any maps actually have a >> 'pinning' BTF attribute set, we default the new option to enabled, on the >> assumption that seamless pinning is what most callers want. >> >> When a map has a pin_path set at load time, libbpf will compare the map >> pinned at that location (if any), and if the attributes match, will re-use >> that map instead of creating a new one. If no existing map is found, the >> newly created map will instead be pinned at the location. >> >> Programs wanting to customise the pinning can override the pinning paths >> using bpf_map__set_pin_path() before calling bpf_object__load(). >> >> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> >> --- > > How have you tested this? From reading the code, all the maps will be > pinned irregardless of their .pinning setting? No, build_pin_path() checks map->pinning :) > Please add proper tests to test_progs, testing various modes and > overrides. Can do. > You keep trying to add more and more knobs :) Please stop doing that, > even if we have a good mechanism for extensibility, it doesn't mean we > need to increase a proliferation of options. But I like options! ;) > Each option has to be tested. In current version of your patches, you > have something like 4 or 5 different knobs, do you really want to > write tests testing each of them? ;) Heh, I guess I can cut down the number of options to the number of tests :P > Another high-level feedback. I think having separate passes over all > maps (build_map_pin_paths, reuse, then we already have create_maps) is > actually making everything more verbose and harder to extend. I'm > thinking about all these as sub-steps of map creation. Can you please > try refactoring so all these steps are happening per each map in one > place: if map needs to be pinned, check if it can be reused, if not - > create it. This actually will allow to handle races better, because > you will be able to retry easily, while if it's all spread in > independent passes, it becomes much harder. Please consider that. We'll need at least two passes: set pin_path on open, and check reuse / create / pin on load. Don't have any objections to consolidating the other passes into create_maps; will fix, along with your comments below. -Toke
