diff options
| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-10-07 07:02:42 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-10-17 10:30:18 -0300 |
| commit | cc956e0cd6a405fbc6ad3055cbbdb178562ef27d (patch) | |
| tree | 42a419524dac95c6c239347d18b4a0c73ba6f2ad | |
| parent | ac416cf3eff650ad4b6dabc3407c7174e1826db9 (diff) | |
perf evsel: Mark the event as supported when retrying an open
Opening a group with perf record on a machine with perf_event_paranoid >
1 and no CAP_PERFMON fails the first perf_event_open() with EACCES, after
which evsel__open_cpu() clears evsel->supported; evsel__fallback() then
adds exclude_kernel and record__open() retries, and the retry succeeds
with supported left false. get_group_fd() treats unsupported events as
ungroupable, so the retry opens the group members without their leader:
sys_perf_event_open: pid 12345 cpu 0 group_fd -1
FAILED '.../test-record-group-sampling1' - group failure
which fails the group subtests of "perf test 82", the Perf attribute
expectations test, when it is run as a regular user, while it passes as
root or with CAP_PERFMON, where the first open doesn't fail.
commit 2cc7aa995ce9 ("perf stat: Refactor retry/skip/fatal error handling")
dropped the pos->supported = true that record__open() did after a
successful open and moved the resets into the stat code only, while
saying "When an event is tried the supported is set to true again". Do
that in evsel__open_cpu(), which every open entry point funnels through,
so that a retry describes its own try instead of the previous failure.
Fixes: 2cc7aa995ce9ecd8 ("perf stat: Refactor retry/skip/fatal error handling")
Reviewed-by: Ian Rogers <irogers@google.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Ian Rogers <irogers@google.com>
Assisted-by: LLM
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
| -rw-r--r-- | tools/perf/util/evsel.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 9c5e7510f0c0..e61f309e93dc 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -3014,6 +3014,12 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus, enum rlimit_action set_rlimit = NO_CHANGE; struct perf_cpu cpu; + /* + * A failed attempt being retried after evsel__fallback() would + * otherwise keep group members out of their group in get_group_fd(). + */ + evsel->supported = true; + if (evsel__is_retire_lat(evsel)) { err = evsel__tpebs_open(evsel); goto out; |