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Date: Thu, 25 Apr 2024 15:05:09 -0700
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Message-ID: <20240425220509.1751260-1-yabinc@google.com>
Subject: [PATCH] perf/core: Trim dyn_size if raw data is absent
From: Yabin Cui <yabinc@google.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Yabin Cui <yabinc@google.com>
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Currently, perf_tp_event() always allocates space for raw sample data,
even when the PERF_SAMPLE_RAW flag is not set. This leads to unused
spaces within generated sample records.

This patch reduces dyn_size when PERF_SAMPLE_RAW is not present,
ensuring sample records use only the necessary amount of space.

Fixes: 0a9081cf0a11 ("perf/core: Add perf_sample_save_raw_data() helper")
Signed-off-by: Yabin Cui <yabinc@google.com>
---
 kernel/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 724e6d7e128f..d68ecdc264d3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7688,6 +7688,10 @@ void perf_prepare_sample(struct perf_sample_data *data,
 		data->raw = NULL;
 		data->dyn_size += sizeof(u64);
 		data->sample_flags |= PERF_SAMPLE_RAW;
+	} else if ((data->sample_flags & ~sample_type) & PERF_SAMPLE_RAW) {
+		data->dyn_size -= data->raw->size + sizeof(u32);
+		data->raw = NULL;
+		data->sample_flags &= ~PERF_SAMPLE_RAW;
 	}
 
 	if (filtered_sample_type & PERF_SAMPLE_BRANCH_STACK) {
-- 
2.44.0.769.g3c40516874-goog