linux-kernel - [PATCH] perf inject: Fix --buildid-all not to eat up MMAP2

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Date:   Wed, 22 Feb 2023 23:01:55 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] perf inject: Fix --buildid-all not to eat up MMAP2

When MMAP2 has PERF_RECORD_MISC_MMAP_BUILD_ID flag, it means the record
already has the build-id info.  So it marks the DSO as hit, to skip if
the same DSO is not processed if it happens to miss the build-id later.

But it missed to copy the MMAP2 record itself so it'd fail to symbolize
samples for those regions.

For example, the following generates 249 MMAP2 events.

  $ perf record --buildid-mmap -o- true | perf report --stat -i- | grep MMAP2
           MMAP2 events:        249  (86.8%)

Adding perf inject should not change the number of events like this

  $ perf record --buildid-mmap -o- true | perf inject -b | \
  > perf report --stat -i- | grep MMAP2
           MMAP2 events:        249  (86.5%)

But when --buildid-all is used, it eats most of the MMAP2 events.

  $ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \
  > perf report --stat -i- | grep MMAP2
           MMAP2 events:          1  ( 2.5%)

With this patch, it shows the original number now.

  $ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \
  > perf report --stat -i- | grep MMAP2
           MMAP2 events:        249  (86.5%)

Cc: stable@...r.kernel.org
Fixes: f7fc0d1c915a ("perf inject: Do not inject BUILD_ID record if MMAP2 has it")
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/builtin-inject.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index f8182417b734..10bb1d494258 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -538,6 +538,7 @@ static int perf_event__repipe_buildid_mmap2(struct perf_tool *tool,
 			dso->hit = 1;
 		}
 		dso__put(dso);
+		perf_event__repipe(tool, event, sample, machine);
 		return 0;
 	}
 
-- 
2.39.2.637.g21b0678d19-goog