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Date:   Mon, 27 Nov 2023 14:08:13 -0800
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Subject: [PATCH v5 01/50] perf comm: Use regular mutex
From:   Ian Rogers <irogers@google.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Nick Terrell <terrelln@fb.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        "Steinar H. Gunderson" <sesse@google.com>,
        Liam Howlett <liam.howlett@oracle.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Colin Ian King <colin.i.king@gmail.com>,
        Dmitrii Dolgov <9erthalion6@gmail.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Ming Wang <wangming01@loongson.cn>,
        James Clark <james.clark@arm.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Leo Yan <leo.yan@linaro.org>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        German Gomez <german.gomez@arm.com>,
        Changbin Du <changbin.du@huawei.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Li Dong <lidong@vivo.com>,
        Sandipan Das <sandipan.das@amd.com>,
        liuwenyu <liuwenyu7@huawei.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org,
        Guilherme Amadio <amadio@gentoo.org>
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Precedence: bulk

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@google.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;
 }
-- 
2.43.0.rc1.413.gea7ed67945-goog