This is a note to let you know that I've just added the patch titled bpftool: profile online CPUs instead of possible to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bpftool-profile-online-cpus-instead-of-possible.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d64f377a43b9e0f402a2007d1ac2da313e268d52 Author: Tonghao Zhang <tong@xxxxxxxxxxxxx> Date: Thu Feb 2 21:17:01 2023 +0800 bpftool: profile online CPUs instead of possible [ Upstream commit 377c16fa3f3c60d21e4b05314c8be034ce37f2eb ] The number of online cpu may be not equal to possible cpu. "bpftool prog profile" can not create pmu event on possible but on online cpu. $ dmidecode -s system-product-name PowerEdge R620 $ cat /sys/devices/system/cpu/possible 0-47 $ cat /sys/devices/system/cpu/online 0-31 Disable cpu dynamically: $ echo 0 > /sys/devices/system/cpu/cpuX/online If one cpu is offline, perf_event_open will return ENODEV. To fix this issue: * check value returned and skip offline cpu. * close pmu_fd immediately on error path, avoid fd leaking. Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command") Signed-off-by: Tonghao Zhang <tong@xxxxxxxxxxxxx> Cc: Quentin Monnet <quentin@xxxxxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Cc: Andrii Nakryiko <andrii@xxxxxxxxxx> Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx> Cc: Song Liu <song@xxxxxxxxxx> Cc: Yonghong Song <yhs@xxxxxx> Cc: John Fastabend <john.fastabend@xxxxxxxxx> Cc: KP Singh <kpsingh@xxxxxxxxxx> Cc: Stanislav Fomichev <sdf@xxxxxxxxxx> Cc: Hao Luo <haoluo@xxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx> Link: https://lore.kernel.org/r/20230202131701.29519-1-tong@xxxxxxxxxxxxx Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index f8755beb3d9eb..bdd4d3b12f6c0 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -2064,10 +2064,38 @@ static void profile_close_perf_events(struct profiler_bpf *obj) profile_perf_event_cnt = 0; } +static int profile_open_perf_event(int mid, int cpu, int map_fd) +{ + int pmu_fd; + + pmu_fd = syscall(__NR_perf_event_open, &metrics[mid].attr, + -1 /*pid*/, cpu, -1 /*group_fd*/, 0); + if (pmu_fd < 0) { + if (errno == ENODEV) { + p_info("cpu %d may be offline, skip %s profiling.", + cpu, metrics[mid].name); + profile_perf_event_cnt++; + return 0; + } + return -1; + } + + if (bpf_map_update_elem(map_fd, + &profile_perf_event_cnt, + &pmu_fd, BPF_ANY) || + ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0)) { + close(pmu_fd); + return -1; + } + + profile_perf_events[profile_perf_event_cnt++] = pmu_fd; + return 0; +} + static int profile_open_perf_events(struct profiler_bpf *obj) { unsigned int cpu, m; - int map_fd, pmu_fd; + int map_fd; profile_perf_events = calloc( sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric); @@ -2086,17 +2114,11 @@ static int profile_open_perf_events(struct profiler_bpf *obj) if (!metrics[m].selected) continue; for (cpu = 0; cpu < obj->rodata->num_cpu; cpu++) { - pmu_fd = syscall(__NR_perf_event_open, &metrics[m].attr, - -1/*pid*/, cpu, -1/*group_fd*/, 0); - if (pmu_fd < 0 || - bpf_map_update_elem(map_fd, &profile_perf_event_cnt, - &pmu_fd, BPF_ANY) || - ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0)) { + if (profile_open_perf_event(m, cpu, map_fd)) { p_err("failed to create event %s on cpu %d", metrics[m].name, cpu); return -1; } - profile_perf_events[profile_perf_event_cnt++] = pmu_fd; } } return 0;