* [PATCH v1] perf record: Ensure space for lost samples
@ 2024-06-07 20:47 Ian Rogers
2024-06-09 2:31 ` Namhyung Kim
0 siblings, 1 reply; 2+ messages in thread
From: Ian Rogers @ 2024-06-07 20:47 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa,
Ian Rogers, Adrian Hunter, Kan Liang, linux-perf-users,
linux-kernel
Cc: Milian Wolff
Previous allocation didn't account for sample ID written after the
lost samples event. Switch from malloc/free to a stack allocation.
Reported-by: Milian Wolff <milian.wolff@kdab.com>
Closes: https://lore.kernel.org/linux-perf-users/23879991.0LEYPuXRzz@milian-workstation/
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/lib/perf/include/perf/event.h | 3 +++
tools/perf/builtin-record.c | 37 ++++++++++-------------------
2 files changed, 15 insertions(+), 25 deletions(-)
diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
index ae64090184d3..8f3cefef9069 100644
--- a/tools/lib/perf/include/perf/event.h
+++ b/tools/lib/perf/include/perf/event.h
@@ -77,6 +77,9 @@ struct perf_record_lost_samples {
__u64 lost;
};
+#define MAX_ID_HDR_ENTRIES 6
+#define PERF_RECORD_MAX_LOST_SAMPLE_AND_ID_SIZE \
+ (sizeof(struct perf_record_lost_samples) + MAX_ID_HDR_ENTRIES * sizeof(__u64))
/*
* PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID | PERF_FORMAT_LOST
*/
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 66a3de8ac661..1615a1723fb9 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1926,7 +1926,10 @@ static void __record__save_lost_samples(struct record *rec, struct evsel *evsel,
static void record__read_lost_samples(struct record *rec)
{
struct perf_session *session = rec->session;
- struct perf_record_lost_samples *lost = NULL;
+ union {
+ struct perf_record_lost_samples lost;
+ char lost_and_sample_id[PERF_RECORD_MAX_LOST_SAMPLE_AND_ID_SIZE];
+ } lost;
struct evsel *evsel;
/* there was an error during record__open */
@@ -1951,20 +1954,13 @@ static void record__read_lost_samples(struct record *rec)
if (perf_evsel__read(&evsel->core, x, y, &count) < 0) {
pr_debug("read LOST count failed\n");
- goto out;
+ return;
}
if (count.lost) {
- if (!lost) {
- lost = zalloc(sizeof(*lost) +
- session->machines.host.id_hdr_size);
- if (!lost) {
- pr_debug("Memory allocation failed\n");
- return;
- }
- lost->header.type = PERF_RECORD_LOST_SAMPLES;
- }
- __record__save_lost_samples(rec, evsel, lost,
+ memset(&lost, 0, sizeof(lost));
+ lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
+ __record__save_lost_samples(rec, evsel, &lost.lost,
x, y, count.lost, 0);
}
}
@@ -1972,21 +1968,12 @@ static void record__read_lost_samples(struct record *rec)
lost_count = perf_bpf_filter__lost_count(evsel);
if (lost_count) {
- if (!lost) {
- lost = zalloc(sizeof(*lost) +
- session->machines.host.id_hdr_size);
- if (!lost) {
- pr_debug("Memory allocation failed\n");
- return;
- }
- lost->header.type = PERF_RECORD_LOST_SAMPLES;
- }
- __record__save_lost_samples(rec, evsel, lost, 0, 0, lost_count,
+ memset(&lost, 0, sizeof(lost));
+ lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
+ __record__save_lost_samples(rec, evsel, &lost.lost, 0, 0, lost_count,
PERF_RECORD_MISC_LOST_SAMPLES_BPF);
}
}
-out:
- free(lost);
}
static volatile sig_atomic_t workload_exec_errno;
@@ -3198,7 +3185,7 @@ static int switch_output_setup(struct record *rec)
unsigned long val;
/*
- * If we're using --switch-output-events, then we imply its
+ * If we're using --switch-output-events, then we imply its
* --switch-output=signal, as we'll send a SIGUSR2 from the side band
* thread to its parent.
*/
--
2.45.2.505.gda0bf45e8d-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v1] perf record: Ensure space for lost samples
2024-06-07 20:47 [PATCH v1] perf record: Ensure space for lost samples Ian Rogers
@ 2024-06-09 2:31 ` Namhyung Kim
0 siblings, 0 replies; 2+ messages in thread
From: Namhyung Kim @ 2024-06-09 2:31 UTC (permalink / raw)
To: Ian Rogers
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter,
Kan Liang, linux-perf-users, linux-kernel, Milian Wolff
On Fri, Jun 07, 2024 at 01:47:27PM -0700, Ian Rogers wrote:
> Previous allocation didn't account for sample ID written after the
> lost samples event. Switch from malloc/free to a stack allocation.
>
> Reported-by: Milian Wolff <milian.wolff@kdab.com>
> Closes: https://lore.kernel.org/linux-perf-users/23879991.0LEYPuXRzz@milian-workstation/
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/lib/perf/include/perf/event.h | 3 +++
> tools/perf/builtin-record.c | 37 ++++++++++-------------------
> 2 files changed, 15 insertions(+), 25 deletions(-)
>
> diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
> index ae64090184d3..8f3cefef9069 100644
> --- a/tools/lib/perf/include/perf/event.h
> +++ b/tools/lib/perf/include/perf/event.h
> @@ -77,6 +77,9 @@ struct perf_record_lost_samples {
> __u64 lost;
> };
>
> +#define MAX_ID_HDR_ENTRIES 6
> +#define PERF_RECORD_MAX_LOST_SAMPLE_AND_ID_SIZE \
> + (sizeof(struct perf_record_lost_samples) + MAX_ID_HDR_ENTRIES * sizeof(__u64))
> /*
> * PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID | PERF_FORMAT_LOST
> */
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 66a3de8ac661..1615a1723fb9 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1926,7 +1926,10 @@ static void __record__save_lost_samples(struct record *rec, struct evsel *evsel,
> static void record__read_lost_samples(struct record *rec)
> {
> struct perf_session *session = rec->session;
> - struct perf_record_lost_samples *lost = NULL;
> + union {
> + struct perf_record_lost_samples lost;
> + char lost_and_sample_id[PERF_RECORD_MAX_LOST_SAMPLE_AND_ID_SIZE];
> + } lost;
Can we make it struct and keep the sample_id part only?
Other than that, looks good to me.
Thanks,
Namhyung
> struct evsel *evsel;
>
> /* there was an error during record__open */
> @@ -1951,20 +1954,13 @@ static void record__read_lost_samples(struct record *rec)
>
> if (perf_evsel__read(&evsel->core, x, y, &count) < 0) {
> pr_debug("read LOST count failed\n");
> - goto out;
> + return;
> }
>
> if (count.lost) {
> - if (!lost) {
> - lost = zalloc(sizeof(*lost) +
> - session->machines.host.id_hdr_size);
> - if (!lost) {
> - pr_debug("Memory allocation failed\n");
> - return;
> - }
> - lost->header.type = PERF_RECORD_LOST_SAMPLES;
> - }
> - __record__save_lost_samples(rec, evsel, lost,
> + memset(&lost, 0, sizeof(lost));
> + lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
> + __record__save_lost_samples(rec, evsel, &lost.lost,
> x, y, count.lost, 0);
> }
> }
> @@ -1972,21 +1968,12 @@ static void record__read_lost_samples(struct record *rec)
>
> lost_count = perf_bpf_filter__lost_count(evsel);
> if (lost_count) {
> - if (!lost) {
> - lost = zalloc(sizeof(*lost) +
> - session->machines.host.id_hdr_size);
> - if (!lost) {
> - pr_debug("Memory allocation failed\n");
> - return;
> - }
> - lost->header.type = PERF_RECORD_LOST_SAMPLES;
> - }
> - __record__save_lost_samples(rec, evsel, lost, 0, 0, lost_count,
> + memset(&lost, 0, sizeof(lost));
> + lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
> + __record__save_lost_samples(rec, evsel, &lost.lost, 0, 0, lost_count,
> PERF_RECORD_MISC_LOST_SAMPLES_BPF);
> }
> }
> -out:
> - free(lost);
> }
>
> static volatile sig_atomic_t workload_exec_errno;
> @@ -3198,7 +3185,7 @@ static int switch_output_setup(struct record *rec)
> unsigned long val;
>
> /*
> - * If we're using --switch-output-events, then we imply its
> + * If we're using --switch-output-events, then we imply its
> * --switch-output=signal, as we'll send a SIGUSR2 from the side band
> * thread to its parent.
> */
> --
> 2.45.2.505.gda0bf45e8d-goog
>
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