diff options
| author | Michael Petlan <mpetlan@redhat.com> | 2026-04-02 17:51:18 +0300 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2026-04-03 04:43:35 +0300 |
| commit | 11e8d234d4be7af401e8a24e078005ecd9bc1d1a (patch) | |
| tree | c5eb33b0c7dd78dcce6dd52792e19cb2cbf9d257 | |
| parent | 85a9a4abcdc09ee941273c99d3ad0bc2ddef09ea (diff) | |
| download | linux-11e8d234d4be7af401e8a24e078005ecd9bc1d1a.tar.xz | |
perf trace: Fix potential u64 underflow in duration calculation
Although it happens very rarely, in case of out-of-order events (i.e.
due to CPU migration when a syscall is executed), the calculation of
event duration might underflow and thus a bogus value is printed:
2.804 ( 0.001 ms): :49553/49553 rt_sigaction(sig: QUIT, act: 0x7fff403ed6e0, oact: 0x7fff403ed780, sigsetsize: 8) = 0
2.807 ( 0.001 ms): :49553/49553 rt_sigaction(sig: CHLD, act: 0x7fff403ed6e0, oact: 0x7fff403ed780, sigsetsize: 8) = 0
2.815 (18446744073709.438 ms): :49553/49553 execve(filename: 0xbb173a30, argv: 0x55aabb171930, envp: 0x55aabb171120) = 0
2.815 ( 0.534 ms): pwd/49553 ... [continued]: execve()) = 0
Check for possible underflow first and in case of a bogus value, do
not print it.
2.804 ( 0.001 ms): :49553/49553 rt_sigaction(sig: QUIT, act: 0x7fff403ed6e0, oact: 0x7fff403ed780, sigsetsize: 8) = 0
2.807 ( 0.001 ms): :49553/49553 rt_sigaction(sig: CHLD, act: 0x7fff403ed6e0, oact: 0x7fff403ed780, sigsetsize: 8) = 0
2.815 ( ): :49553/49553 execve(filename: 0xbb173a30, argv: 0x55aabb171930, envp: 0x55aabb171120) = 0
2.815 ( 0.534 ms): pwd/49553 ... [continued]: execve()) = 0
Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
| -rw-r--r-- | tools/perf/builtin-trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index d121640ace6e..873d144807e2 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -2960,7 +2960,7 @@ static int trace__sys_exit(struct trace *trace, struct evsel *evsel, ++trace->stats.vfs_getname; } - if (ttrace->entry_time) { + if (ttrace->entry_time && sample->time >= ttrace->entry_time) { duration = sample->time - ttrace->entry_time; if (trace__filter_duration(trace, duration)) goto out; |