* [PATCH] perf record: Do not fail with an exiting thread
@ 2026-11-11 19:23 Namhyung Kim
2026-11-11 19:54 ` sashiko-bot
2026-11-12 0:40 ` Ian Rogers
0 siblings, 2 replies; 3+ messages in thread
From: Namhyung Kim @ 2026-11-11 19:23 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: Ian Rogers, Jiri Olsa, Adrian Hunter, James Clark, Peter Zijlstra,
Ingo Molnar, LKML, linux-perf-users
When a thread in the target process exits during the synthesize, it
can fail due to the missing /proc entry. So __perf_event__synthesize_
thread() ignores the return value of __event__synthesize_thread().
Do the same in the perf_event__synthesize_thread_map() too.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/synthetic-events.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index b9dbd105cdc37f38..3c8d29f27fd91a2c 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -991,6 +991,7 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
union perf_event *comm_event, *mmap_event, *fork_event;
union perf_event *namespaces_event;
int err = -1, thread, j;
+ int synthesized = 0;
comm_event = malloc(sizeof(comm_event->comm) + machine->id_hdr_size);
if (comm_event == NULL)
@@ -1010,16 +1011,19 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
if (namespaces_event == NULL)
goto out_free_fork;
- err = 0;
for (thread = 0; thread < threads->nr; ++thread) {
+ /*
+ * We may race with exiting thread, so don't stop just because
+ * one thread couldn't be synthesized.
+ */
if (__event__synthesize_thread(comm_event, mmap_event,
fork_event, namespaces_event,
perf_thread_map__pid(threads, thread), 0,
process, tool, machine,
- needs_mmap, mmap_data)) {
- err = -1;
- break;
- }
+ needs_mmap, mmap_data))
+ continue;
+
+ synthesized++;
/*
* comm.pid is set to thread group id by
@@ -1037,17 +1041,19 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
}
/* if not, generate events for it */
- if (need_leader &&
- __event__synthesize_thread(comm_event, mmap_event,
+ if (need_leader) {
+ __event__synthesize_thread(comm_event, mmap_event,
fork_event, namespaces_event,
comm_event->comm.pid, 0,
process, tool, machine,
- needs_mmap, mmap_data)) {
- err = -1;
- break;
+ needs_mmap, mmap_data);
}
}
}
+
+ if (synthesized)
+ err = 0;
+
free(namespaces_event);
out_free_fork:
free(fork_event);
--
2.56.0.567.gdb80ae8cd5-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] perf record: Do not fail with an exiting thread
2026-11-11 19:23 [PATCH] perf record: Do not fail with an exiting thread Namhyung Kim
@ 2026-11-11 19:54 ` sashiko-bot
2026-11-12 0:40 ` Ian Rogers
1 sibling, 0 replies; 3+ messages in thread
From: sashiko-bot @ 2026-11-11 19:54 UTC (permalink / raw)
To: Namhyung Kim; +Cc: linux-perf-users
> When a thread in the target process exits during the synthesize, it
> can fail due to the missing /proc entry. So __perf_event__synthesize_
> thread() ignores the return value of __event__synthesize_thread().
>
> Do the same in the perf_event__synthesize_thread_map() too.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261111192328.3917311-1-namhyung@kernel.org?part=1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] perf record: Do not fail with an exiting thread
2026-11-11 19:23 [PATCH] perf record: Do not fail with an exiting thread Namhyung Kim
2026-11-11 19:54 ` sashiko-bot
@ 2026-11-12 0:40 ` Ian Rogers
1 sibling, 0 replies; 3+ messages in thread
From: Ian Rogers @ 2026-11-12 0:40 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, Jiri Olsa, Adrian Hunter, James Clark,
Peter Zijlstra, Ingo Molnar, LKML, linux-perf-users
On Wed, Nov 11, 2026 at 11:23 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> When a thread in the target process exits during the synthesize, it
> can fail due to the missing /proc entry. So __perf_event__synthesize_
> thread() ignores the return value of __event__synthesize_thread().
>
> Do the same in the perf_event__synthesize_thread_map() too.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> tools/perf/util/synthetic-events.c | 26 ++++++++++++++++----------
> 1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index b9dbd105cdc37f38..3c8d29f27fd91a2c 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -991,6 +991,7 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
> union perf_event *comm_event, *mmap_event, *fork_event;
> union perf_event *namespaces_event;
> int err = -1, thread, j;
> + int synthesized = 0;
>
> comm_event = malloc(sizeof(comm_event->comm) + machine->id_hdr_size);
> if (comm_event == NULL)
> @@ -1010,16 +1011,19 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
> if (namespaces_event == NULL)
> goto out_free_fork;
>
> - err = 0;
> for (thread = 0; thread < threads->nr; ++thread) {
> + /*
> + * We may race with exiting thread, so don't stop just because
> + * one thread couldn't be synthesized.
> + */
> if (__event__synthesize_thread(comm_event, mmap_event,
> fork_event, namespaces_event,
> perf_thread_map__pid(threads, thread), 0,
> process, tool, machine,
> - needs_mmap, mmap_data)) {
> - err = -1;
> - break;
> - }
> + needs_mmap, mmap_data))
> + continue;
> +
> + synthesized++;
>
> /*
> * comm.pid is set to thread group id by
> @@ -1037,17 +1041,19 @@ int perf_event__synthesize_thread_map(const struct perf_tool *tool,
> }
>
> /* if not, generate events for it */
> - if (need_leader &&
> - __event__synthesize_thread(comm_event, mmap_event,
> + if (need_leader) {
> + __event__synthesize_thread(comm_event, mmap_event,
> fork_event, namespaces_event,
> comm_event->comm.pid, 0,
> process, tool, machine,
> - needs_mmap, mmap_data)) {
> - err = -1;
> - break;
> + needs_mmap, mmap_data);
> }
> }
> }
> +
> + if (synthesized)
> + err = 0;
> +
> free(namespaces_event);
> out_free_fork:
> free(fork_event);
> --
> 2.56.0.567.gdb80ae8cd5-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-11-11 19:23 [PATCH] perf record: Do not fail with an exiting thread Namhyung Kim
2026-11-11 19:54 ` sashiko-bot
2026-11-12 0:40 ` Ian Rogers
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