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Date:   Fri, 26 Aug 2022 09:42:25 -0700
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Subject: [PATCH v4 01/18] perf mutex: Wrapped usage of mutex and cond
From:   Ian Rogers <irogers@google.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
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Cc:     Ian Rogers <irogers@google.com>
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From: Pavithra Gurushankar <gpavithrasha@gmail.com>

Added a new header file mutex.h that wraps the usage of
pthread_mutex_t and pthread_cond_t. By abstracting these it is
possible to introduce error checking.

Signed-off-by: Pavithra Gurushankar <gpavithrasha@gmail.com>
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/Build   |   1 +
 tools/perf/util/mutex.c | 117 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/mutex.h |  48 +++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 tools/perf/util/mutex.c
 create mode 100644 tools/perf/util/mutex.h

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 9dfae1bda9cc..8fd6dc8de521 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -143,6 +143,7 @@ perf-y += branch.o
 perf-y += mem2node.o
 perf-y += clockid.o
 perf-y += list_sort.o
+perf-y += mutex.o
 
 perf-$(CONFIG_LIBBPF) += bpf-loader.o
 perf-$(CONFIG_LIBBPF) += bpf_map.o
diff --git a/tools/perf/util/mutex.c b/tools/perf/util/mutex.c
new file mode 100644
index 000000000000..5029237164e5
--- /dev/null
+++ b/tools/perf/util/mutex.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "mutex.h"
+
+#include "debug.h"
+#include <linux/string.h>
+#include <errno.h>
+
+static void check_err(const char *fn, int err)
+{
+	char sbuf[STRERR_BUFSIZE];
+
+	if (err == 0)
+		return;
+
+	pr_err("%s error: '%s'\n", fn, str_error_r(err, sbuf, sizeof(sbuf)));
+}
+
+#define CHECK_ERR(err) check_err(__func__, err)
+
+static void __mutex_init(struct mutex *mtx, bool pshared)
+{
+	pthread_mutexattr_t attr;
+
+	CHECK_ERR(pthread_mutexattr_init(&attr));
+
+#ifndef NDEBUG
+	/* In normal builds enable error checking, such as recursive usage. */
+	CHECK_ERR(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK));
+#endif
+	if (pshared)
+		CHECK_ERR(pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED));
+
+	CHECK_ERR(pthread_mutex_init(&mtx->lock, &attr));
+	CHECK_ERR(pthread_mutexattr_destroy(&attr));
+}
+
+void mutex_init(struct mutex *mtx)
+{
+	__mutex_init(mtx, /*pshared=*/false);
+}
+
+void mutex_init_pshared(struct mutex *mtx)
+{
+	__mutex_init(mtx, /*pshared=*/true);
+}
+
+void mutex_destroy(struct mutex *mtx)
+{
+	CHECK_ERR(pthread_mutex_destroy(&mtx->lock));
+}
+
+void mutex_lock(struct mutex *mtx)
+{
+	CHECK_ERR(pthread_mutex_lock(&mtx->lock));
+}
+
+void mutex_unlock(struct mutex *mtx)
+{
+	CHECK_ERR(pthread_mutex_unlock(&mtx->lock));
+}
+
+bool mutex_trylock(struct mutex *mtx)
+{
+	int ret = pthread_mutex_trylock(&mtx->lock);
+
+	if (ret == 0)
+		return true; /* Lock acquired. */
+
+	if (ret == EBUSY)
+		return false; /* Lock busy. */
+
+	/* Print error. */
+	CHECK_ERR(ret);
+	return false;
+}
+
+static void __cond_init(struct cond *cnd, bool pshared)
+{
+	pthread_condattr_t attr;
+
+	CHECK_ERR(pthread_condattr_init(&attr));
+	if (pshared)
+		CHECK_ERR(pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED));
+
+	CHECK_ERR(pthread_cond_init(&cnd->cond, &attr));
+	CHECK_ERR(pthread_condattr_destroy(&attr));
+}
+
+void cond_init(struct cond *cnd)
+{
+	__cond_init(cnd, /*pshared=*/false);
+}
+
+void cond_init_pshared(struct cond *cnd)
+{
+	__cond_init(cnd, /*pshared=*/true);
+}
+
+void cond_destroy(struct cond *cnd)
+{
+	CHECK_ERR(pthread_cond_destroy(&cnd->cond));
+}
+
+void cond_wait(struct cond *cnd, struct mutex *mtx)
+{
+	CHECK_ERR(pthread_cond_wait(&cnd->cond, &mtx->lock));
+}
+
+void cond_signal(struct cond *cnd)
+{
+	CHECK_ERR(pthread_cond_signal(&cnd->cond));
+}
+
+void cond_broadcast(struct cond *cnd)
+{
+	CHECK_ERR(pthread_cond_broadcast(&cnd->cond));
+}
diff --git a/tools/perf/util/mutex.h b/tools/perf/util/mutex.h
new file mode 100644
index 000000000000..cfff32a902d9
--- /dev/null
+++ b/tools/perf/util/mutex.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_MUTEX_H
+#define __PERF_MUTEX_H
+
+#include <pthread.h>
+#include <stdbool.h>
+
+/*
+ * A wrapper around the mutex implementation that allows perf to error check
+ * usage, etc.
+ */
+struct mutex {
+	pthread_mutex_t lock;
+};
+
+/* A wrapper around the condition variable implementation. */
+struct cond {
+	pthread_cond_t cond;
+};
+
+/* Default initialize the mtx struct. */
+void mutex_init(struct mutex *mtx);
+/*
+ * Initialize the mtx struct and set the process-shared rather than default
+ * process-private attribute.
+ */
+void mutex_init_pshared(struct mutex *mtx);
+void mutex_destroy(struct mutex *mtx);
+
+void mutex_lock(struct mutex *mtx);
+void mutex_unlock(struct mutex *mtx);
+/* Tries to acquire the lock and returns true on success. */
+bool mutex_trylock(struct mutex *mtx);
+
+/* Default initialize the cond struct. */
+void cond_init(struct cond *cnd);
+/*
+ * Initialize the cond struct and specify the process-shared rather than default
+ * process-private attribute.
+ */
+void cond_init_pshared(struct cond *cnd);
+void cond_destroy(struct cond *cnd);
+
+void cond_wait(struct cond *cnd, struct mutex *mtx);
+void cond_signal(struct cond *cnd);
+void cond_broadcast(struct cond *cnd);
+
+#endif /* __PERF_MUTEX_H */
-- 
2.37.2.672.g94769d06f0-goog