linux-kernel - [PATCH v1 1/3] perf dso: Minor refactor to allow Wthread-safety analysis

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Message-ID: <20250519224645.1810891-1-irogers@google.com>
Date: Mon, 19 May 2025 15:46:43 -0700
From: Ian Rogers <irogers@...gle.com>
To: langfei@...wei.com, 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>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, James Clark <james.clark@...aro.org>, 
	Chaitanya S Prakash <chaitanyas.prakash@....com>, Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, 
	Stephen Brennan <stephen.s.brennan@...cle.com>, Howard Chu <howardchu95@...il.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: [PATCH v1 1/3] perf dso: Minor refactor to allow Wthread-safety analysis

The pattern:
```
if (x) {
   lock(...)
}
block1;
if (x) {
   unlock(...)
}
```
defeats clang's -Wthread-safety analysis where it complains of locks
held on one path and not another. Add helper functions for "block1"
then restructure as:
```
if (x) {
   lock(...);
   block1();
   unlock(...);
} else {
   block1();
}
```

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/dso.c | 45 +++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 8619b6eea62d..057fcf4225ac 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1349,6 +1349,16 @@ struct dso *machine__findnew_kernel(struct machine *machine, const char *name,
 	return dso;
 }
 
+static void __dso__set_long_name_id(struct dso *dso, const char *name, bool name_allocated)
+{
+	if (dso__long_name_allocated(dso))
+		free((char *)dso__long_name(dso));
+
+	RC_CHK_ACCESS(dso)->long_name = name;
+	RC_CHK_ACCESS(dso)->long_name_len = strlen(name);
+	dso__set_long_name_allocated(dso, name_allocated);
+}
+
 static void dso__set_long_name_id(struct dso *dso, const char *name, bool name_allocated)
 {
 	struct dsos *dsos = dso__dsos(dso);
@@ -1362,18 +1372,11 @@ static void dso__set_long_name_id(struct dso *dso, const char *name, bool name_a
 		 * renaming the dso.
 		 */
 		down_write(&dsos->lock);
-	}
-
-	if (dso__long_name_allocated(dso))
-		free((char *)dso__long_name(dso));
-
-	RC_CHK_ACCESS(dso)->long_name = name;
-	RC_CHK_ACCESS(dso)->long_name_len = strlen(name);
-	dso__set_long_name_allocated(dso, name_allocated);
-
-	if (dsos) {
+		__dso__set_long_name_id(dso, name, name_allocated);
 		dsos->sorted = false;
 		up_write(&dsos->lock);
+	} else {
+		__dso__set_long_name_id(dso, name, name_allocated);
 	}
 }
 
@@ -1451,6 +1454,16 @@ void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated)
 	dso__set_long_name_id(dso, name, name_allocated);
 }
 
+static void __dso__set_short_name(struct dso *dso, const char *name, bool name_allocated)
+{
+	if (dso__short_name_allocated(dso))
+		free((char *)dso__short_name(dso));
+
+	RC_CHK_ACCESS(dso)->short_name		  = name;
+	RC_CHK_ACCESS(dso)->short_name_len	  = strlen(name);
+	dso__set_short_name_allocated(dso, name_allocated);
+}
+
 void dso__set_short_name(struct dso *dso, const char *name, bool name_allocated)
 {
 	struct dsos *dsos = dso__dsos(dso);
@@ -1464,17 +1477,11 @@ void dso__set_short_name(struct dso *dso, const char *name, bool name_allocated)
 		 * renaming the dso.
 		 */
 		down_write(&dsos->lock);
-	}
-	if (dso__short_name_allocated(dso))
-		free((char *)dso__short_name(dso));
-
-	RC_CHK_ACCESS(dso)->short_name		  = name;
-	RC_CHK_ACCESS(dso)->short_name_len	  = strlen(name);
-	dso__set_short_name_allocated(dso, name_allocated);
-
-	if (dsos) {
+		__dso__set_short_name(dso, name, name_allocated);
 		dsos->sorted = false;
 		up_write(&dsos->lock);
+	} else {
+		__dso__set_short_name(dso, name, name_allocated);
 	}
 }
 
-- 
2.49.0.1101.gccaa498523-goog