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From: Ian Rogers <irogers@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>,
	 Kan Liang <kan.liang@linux.intel.com>,
	Sun Haiyong <sunhaiyong@loongson.cn>,
	 Yanteng Si <siyanteng@loongson.cn>,
	linux-perf-users@vger.kernel.org,  linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/4] perf header: Write out even empty die_cpus_list
Date: Sun, 15 Dec 2024 17:46:34 -0800	[thread overview]
Message-ID: <20241216014637.304761-2-irogers@google.com> (raw)
In-Reply-To: <20241216014637.304761-1-irogers@google.com>

Reading the CPU topology is tolerant to the dies_cpus_list being
missing by using the feature's size in the data file/pipe. However,
the feature's size is just the header size and may be
unaligned. Making the header size aligned breaks detecting a missing
die_cpus_list. To allow the header size to be aligned always write the
die_cpus_lists even if empty.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/header.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 048e563069bc..03e43a9894d4 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -628,9 +628,6 @@ static int write_cpu_topology(struct feat_fd *ff,
 			return ret;
 	}
 
-	if (!tp->die_cpus_lists)
-		goto done;
-
 	ret = do_write(ff, &tp->die_cpus_lists, sizeof(tp->die_cpus_lists));
 	if (ret < 0)
 		goto done;
-- 
2.47.1.613.gc27f4b7a9f-goog


  reply	other threads:[~2024-12-16  1:46 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-16  1:46 [PATCH v2 0/4] perf file align features, avoid UB Ian Rogers
2024-12-16  1:46 ` Ian Rogers [this message]
2024-12-16 16:56   ` [PATCH v2 1/4] perf header: Write out even empty die_cpus_list Ian Rogers
2024-12-16  1:46 ` [PATCH v2 2/4] perf synthetic-events: Ensure features are aligned Ian Rogers
2024-12-16  1:46 ` [PATCH v2 3/4] perf machine: Avoid UB by delaying computing branch entries Ian Rogers
2024-12-16  1:46 ` [PATCH v2 4/4] perf record: Assert synthesized events are 8-byte aligned Ian Rogers

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