Hello Alan, On 7/31/24 19:23, Alan Maguire wrote: > On 31/07/2024 11:38, Alexis Lothoré (eBPF Foundation) wrote: [...] >> + pid = getpid(); >> + if (!ASSERT_OK(bpf_map__update_elem(skel->maps.pidmap, &key, >> + sizeof(key), &pid, sizeof(pid), 0), >> + "write pid")) >> + goto cleanup_progs; >> + > > I think it would be worth using a global variable in the BPF program > my_pid, and setting skel->bss->my_pid here as other more up-to-date > tests do (example progs/test_usdt.c, prog_tests/usdt.c). No need for a > separate map anymore. That sounds like a good improvement, thanks for the hint and the example :) I'll spin a new revision with this, and make sure to use it in my next test conversion patches too when relevant. TBH I am not familiar with global variables usage in ebpf/libbpf, so it is not clear for me when I should prefer it over classic maps. From some quick search I feel like it should be the default choice when needing basic controls knobs/feedback on a bpf program from userspace ? Or maybe it should be used even more broadly by default ? >> + /* trigger the syscall on which is attached the tested prog */ >> + if (!ASSERT_OK(syscall(__NR_nanosleep, &req, NULL), "nanosleep")) >> + goto cleanup_progs; >> + >> + if (!ASSERT_OK(bpf_map__lookup_elem(skel->maps.cg_ids, &key, >> + sizeof(key), &kcgid, sizeof(kcgid), >> + 0), >> + "read bpf cgroup id")) >> + goto cleanup_progs; >> + > > ditto here, cg_ids could be a global var cg_id that the bpf prog sets > and we check here via skel->bss->cg_id. ACK, I'll update this too. Thanks, Alexis -- Alexis Lothoré, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
