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Message-Id: <20240607204727.849174-1-irogers@google.com>
Date: Fri, 7 Jun 2024 13:47:27 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Milian Wolff <milian.wolff@...b.com>
Subject: [PATCH v1] perf record: Ensure space for lost samples
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@...b.com>
Closes: https://lore.kernel.org/linux-perf-users/23879991.0LEYPuXRzz@milian-workstation/
Signed-off-by: Ian Rogers <irogers@...gle.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
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