linux-kernel - [PATCH v2 10/10] perf symbol: Fix ENOENT case for filename__read_build

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Message-ID: <20251201205509.195451-11-irogers@google.com>
Date: Mon,  1 Dec 2025 12:55:09 -0800
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>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>, 
	James Clark <james.clark@...aro.org>, John Garry <john.g.garry@...cle.com>, 
	Will Deacon <will@...nel.org>, Leo Yan <leo.yan@...ux.dev>, 
	Athira Rajeev <atrajeev@...ux.ibm.com>, tanze <tanze@...inos.cn>, 
	Stephen Brennan <stephen.s.brennan@...cle.com>, Andi Kleen <ak@...ux.intel.com>, 
	Chun-Tse Shao <ctshao@...gle.com>, Thomas Falcon <thomas.falcon@...el.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, "Dr. David Alan Gilbert" <linux@...blig.org>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, 
	"Krzysztof Łopatowski" <krzysztof.m.lopatowski@...il.com>, 
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>, Alexandre Ghiti <alexghiti@...osinc.com>, 
	Haibo Xu <haibo1.xu@...el.com>, Sergei Trofimovich <slyich@...il.com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org
Subject: [PATCH v2 10/10] perf symbol: Fix ENOENT case for filename__read_build_id

Some callers of filename__read_build_id assume the error value must be
-1, fix by making them handle all < 0 values.

If is_regular_file fails in filename__read_build_id then it could be
the file is missing (ENOENT) and it would be wrong to return
-EWOULDBLOCK in that case. Fix the logic so -EWOULDBLOCK is only
reported if other errors with stat haven't occurred.

Fixes: 834ebb5678d7 ("perf tools: Don't read build-ids from non-regular files")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/builtin-buildid-cache.c | 6 ++++--
 tools/perf/util/symbol.c           | 3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index c98104481c8a..539e779e3268 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -276,12 +276,14 @@ static bool dso__missing_buildid_cache(struct dso *dso, int parm __maybe_unused)
 {
 	char filename[PATH_MAX];
 	struct build_id bid = { .size = 0, };
+	int err;
 
 	if (!dso__build_id_filename(dso, filename, sizeof(filename), false))
 		return true;
 
-	if (filename__read_build_id(filename, &bid) == -1) {
-		if (errno == ENOENT)
+	err = filename__read_build_id(filename, &bid);
+	if (err < 0) {
+		if (err == -ENOENT)
 			return false;
 
 		pr_warning("Problems with %s file, consider removing it from the cache\n",
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 76dc5b70350a..f43e30019e21 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2008,8 +2008,9 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
 	if (!filename)
 		return -EFAULT;
 
+	errno = 0;
 	if (!is_regular_file(filename))
-		return -EWOULDBLOCK;
+		return errno == 0 ? -EWOULDBLOCK : -errno;
 
 	err = kmod_path__parse(&m, filename);
 	if (err)
-- 
2.52.0.158.g65b55ccf14-goog