linux-kernel - [PATCH v4 01/53] perf comm: Use regular mutex

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Message-Id: <20231102175735.2272696-2-irogers@google.com>
Date:   Thu,  2 Nov 2023 10:56:43 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Nick Terrell <terrelln@...com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        "Steinar H. Gunderson" <sesse@...gle.com>,
        Liam Howlett <liam.howlett@...cle.com>,
        Miguel Ojeda <ojeda@...nel.org>,
        Colin Ian King <colin.i.king@...il.com>,
        Dmitrii Dolgov <9erthalion6@...il.com>,
        Yang Jihong <yangjihong1@...wei.com>,
        Ming Wang <wangming01@...ngson.cn>,
        James Clark <james.clark@....com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Leo Yan <leo.yan@...aro.org>,
        Ravi Bangoria <ravi.bangoria@....com>,
        German Gomez <german.gomez@....com>,
        Changbin Du <changbin.du@...wei.com>,
        Paolo Bonzini <pbonzini@...hat.com>, Li Dong <lidong@...o.com>,
        Sandipan Das <sandipan.das@....com>,
        liuwenyu <liuwenyu7@...wei.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: [PATCH v4 01/53] perf comm: Use regular mutex

The rwsem is only after used for writing so switch to a mutex that has
better error checking.

Fixes: 7a8f349e9d14 ("perf rwsem: Add debug mode that uses a mutex")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/comm.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
index afb8d4fd2644..4ae7bc2aa9a6 100644
--- a/tools/perf/util/comm.c
+++ b/tools/perf/util/comm.c
@@ -17,7 +17,7 @@ struct comm_str {
 
 /* Should perhaps be moved to struct machine */
 static struct rb_root comm_str_root;
-static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,};
+static struct mutex comm_str_lock = {.lock = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP,};
 
 static struct comm_str *comm_str__get(struct comm_str *cs)
 {
@@ -30,9 +30,9 @@ static struct comm_str *comm_str__get(struct comm_str *cs)
 static void comm_str__put(struct comm_str *cs)
 {
 	if (cs && refcount_dec_and_test(&cs->refcnt)) {
-		down_write(&comm_str_lock);
+		mutex_lock(&comm_str_lock);
 		rb_erase(&cs->rb_node, &comm_str_root);
-		up_write(&comm_str_lock);
+		mutex_unlock(&comm_str_lock);
 		zfree(&cs->str);
 		free(cs);
 	}
@@ -98,9 +98,9 @@ static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)
 {
 	struct comm_str *cs;
 
-	down_write(&comm_str_lock);
+	mutex_lock(&comm_str_lock);
 	cs = __comm_str__findnew(str, root);
-	up_write(&comm_str_lock);
+	mutex_unlock(&comm_str_lock);
 
 	return cs;
 }
-- 
2.42.0.869.gea05f2083d-goog