[RFC PATCH 06/10] perf workqueue: introduce workqueue struct

[Riccardo Mancini]

This patch adds the workqueue definition, along with simple creation and
destruction functions.
Furthermore, a simple subtest is added.

A workqueue is attached to a pool, on which it executes its workers.
Next patches will introduce workers.

Signed-off-by: Riccardo Mancini <rickyman7@xxxxxxxxx>
---
 tools/perf/tests/workqueue.c          |  92 +++++++++++++
 tools/perf/util/workqueue/Build       |   1 +
 tools/perf/util/workqueue/workqueue.c | 184 ++++++++++++++++++++++++++
 tools/perf/util/workqueue/workqueue.h |  24 ++++
 4 files changed, 301 insertions(+)
 create mode 100644 tools/perf/util/workqueue/workqueue.c
 create mode 100644 tools/perf/util/workqueue/workqueue.h

diff --git a/tools/perf/tests/workqueue.c b/tools/perf/tests/workqueue.c
index 3c64db8203556847..423dc8a92ca2563c 100644
--- a/tools/perf/tests/workqueue.c
+++ b/tools/perf/tests/workqueue.c
@@ -5,6 +5,7 @@
 #include "tests.h"
 #include "util/debug.h"
 #include "util/workqueue/threadpool.h"
+#include "util/workqueue/workqueue.h"
 
 #define DUMMY_FACTOR 100000
 #define N_DUMMY_WORK_SIZES 7
@@ -13,6 +14,11 @@ struct threadpool_test_args_t {
 	int pool_size;
 };
 
+struct workqueue_test_args_t {
+	int pool_size;
+	int n_work_items;
+};
+
 struct test_task {
 	struct task_struct task;
 	int n_threads;
@@ -140,6 +146,58 @@ static int __test__threadpool(void *_args)
 	return 0;
 }
 
+
+static int __workqueue__prepare(struct threadpool_struct **pool,
+				struct workqueue_struct **wq,
+				int pool_size)
+{
+	int ret;
+
+	ret = __threadpool__prepare(pool, pool_size);
+	if (ret)
+		return ret;
+
+	*wq = create_workqueue(*pool);
+	TEST_ASSERT_VAL("workqueue creation failure", *wq);
+	TEST_ASSERT_VAL("workqueue wrong size", workqueue_nr_threads(*wq) == pool_size);
+	TEST_ASSERT_VAL("threadpool is not executing", threadpool_is_busy(*pool));
+
+	return 0;
+}
+
+static int __workqueue__teardown(struct threadpool_struct *pool,
+				struct workqueue_struct *wq)
+{
+	int ret;
+
+	ret = destroy_workqueue(wq);
+	TEST_ASSERT_VAL("workqueue detruction failure", ret == 0);
+
+	ret = __threadpool__teardown(pool);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int __test__workqueue(void *_args)
+{
+	struct workqueue_test_args_t *args = _args;
+	struct threadpool_struct *pool;
+	struct workqueue_struct *wq;
+	int ret;
+
+	ret = __workqueue__prepare(&pool, &wq, args->pool_size);
+	if (ret)
+		return ret;
+
+	ret = __workqueue__teardown(pool, wq);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static const struct threadpool_test_args_t threadpool_test_args[] = {
 	{
 		.pool_size = 1
@@ -158,6 +216,33 @@ static const struct threadpool_test_args_t threadpool_test_args[] = {
 	}
 };
 
+static const struct workqueue_test_args_t workqueue_test_args[] = {
+	{
+		.pool_size = 1,
+		.n_work_items = 1
+	},
+	{
+		.pool_size = 1,
+		.n_work_items = 10
+	},
+	{
+		.pool_size = 2,
+		.n_work_items = 1
+	},
+	{
+		.pool_size = 2,
+		.n_work_items = 100
+	},
+	{
+		.pool_size = 16,
+		.n_work_items = 7
+	},
+	{
+		.pool_size = 16,
+		.n_work_items = 2789
+	}
+};
+
 struct test_case {
 	const char *desc;
 	int (*func)(void *args);
@@ -173,6 +258,13 @@ static struct test_case workqueue_testcase_table[] = {
 		.args = (void *) threadpool_test_args,
 		.n_args = (int)ARRAY_SIZE(threadpool_test_args),
 		.arg_size = sizeof(struct threadpool_test_args_t)
+	},
+	{
+		.desc = "Workqueue",
+		.func = __test__workqueue,
+		.args = (void *) workqueue_test_args,
+		.n_args = (int)ARRAY_SIZE(workqueue_test_args),
+		.arg_size = sizeof(struct workqueue_test_args_t)
 	}
 };
 
diff --git a/tools/perf/util/workqueue/Build b/tools/perf/util/workqueue/Build
index 8b72a6cd4e2cba0d..4af721345c0a6bb7 100644
--- a/tools/perf/util/workqueue/Build
+++ b/tools/perf/util/workqueue/Build
@@ -1 +1,2 @@
 perf-y += threadpool.o
+perf-y += workqueue.o
diff --git a/tools/perf/util/workqueue/workqueue.c b/tools/perf/util/workqueue/workqueue.c
new file mode 100644
index 0000000000000000..5099252a0662e788
--- /dev/null
+++ b/tools/perf/util/workqueue/workqueue.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <pthread.h>
+#include <linux/list.h>
+#include "debug.h"
+#include "workqueue.h"
+
+enum workqueue_status {
+	WORKQUEUE_STATUS__READY,	/* wq is ready to receive work */
+	WORKQUEUE_STATUS__ERROR,
+	WORKQUEUE_STATUS__MAX
+};
+
+struct workqueue_struct {
+	pthread_mutex_t		lock;		/* locking of the thread_pool */
+	pthread_cond_t		idle_cond;	/* all workers are idle cond */
+	struct threadpool_struct *pool;		/* underlying pool */
+	struct task_struct	task;		/* threadpool task */
+	struct list_head	busy_list;	/* busy workers */
+	struct list_head	idle_list;	/* idle workers */
+	struct list_head	pending;	/* pending work items */
+	int			msg_pipe[2];	/* main thread comm pipes */
+	enum workqueue_status	status;
+};
+
+/**
+ * worker_thread - worker function executed on threadpool
+ */
+static void worker_thread(int tidx, struct task_struct *task)
+{
+	struct workqueue_struct *wq = container_of(task, struct workqueue_struct, task);
+
+	pr_debug("hi from worker %d. Pool is in status %d\n", tidx, wq->status);
+}
+
+/**
+ * attach_threadpool_to_workqueue - start @wq workers on @pool
+ */
+static int attach_threadpool_to_workqueue(struct workqueue_struct *wq,
+					struct threadpool_struct *pool)
+{
+	int err;
+
+	if (!threadpool_is_ready(pool)) {
+		pr_err("workqueue: cannot attach to pool: pool is not ready\n");
+		return -1;
+	}
+
+	wq->pool = pool;
+
+	err = execute_in_threadpool(pool, &wq->task);
+	if (err)
+		return -1;
+
+	return 0;
+}
+
+/**
+ * detach_threadpool_from_workqueue - stop @wq workers on @pool
+ */
+static int detach_threadpool_from_workqueue(struct workqueue_struct *wq)
+{
+	int ret, err = 0;
+
+	if (wq->status != WORKQUEUE_STATUS__READY) {
+		pr_err("workqueue: cannot attach to pool: wq is not ready\n");
+		return -1;
+	}
+
+	ret = wait_threadpool(wq->pool);
+	if (ret) {
+		pr_err("workqueue: error waiting threadpool\n");
+		err = -1;
+	}
+
+	wq->pool = NULL;
+	return err;
+}
+
+/**
+ * create_workqueue - create a workqueue associated to @pool
+ *
+ * Only one workqueue can execute on a pool at a time.
+ */
+struct workqueue_struct *create_workqueue(struct threadpool_struct *pool)
+{
+	int err;
+	struct workqueue_struct *wq = malloc(sizeof(struct workqueue_struct));
+
+
+	err = pthread_mutex_init(&wq->lock, NULL);
+	if (err)
+		goto out_free_wq;
+
+	err = pthread_cond_init(&wq->idle_cond, NULL);
+	if (err)
+		goto out_destroy_mutex;
+
+	wq->pool = NULL;
+	INIT_LIST_HEAD(&wq->busy_list);
+	INIT_LIST_HEAD(&wq->idle_list);
+
+	INIT_LIST_HEAD(&wq->pending);
+
+	err = pipe(wq->msg_pipe);
+	if (err)
+		goto out_destroy_cond;
+
+	wq->task.fn = worker_thread;
+
+	err = attach_threadpool_to_workqueue(wq, pool);
+	if (err)
+		goto out_destroy_cond;
+
+	wq->status = WORKQUEUE_STATUS__READY;
+
+	return wq;
+
+out_destroy_cond:
+	pthread_cond_destroy(&wq->idle_cond);
+out_destroy_mutex:
+	pthread_mutex_destroy(&wq->lock);
+out_free_wq:
+	free(wq);
+	return NULL;
+}
+
+/**
+ * destroy_workqueue - stop @wq workers and destroy @wq
+ */
+int destroy_workqueue(struct workqueue_struct *wq)
+{
+	int err = 0, ret;
+
+	ret = detach_threadpool_from_workqueue(wq);
+	if (ret) {
+		pr_err("workqueue: error detaching from threadpool.\n");
+		err = -1;
+	}
+
+	ret = pthread_mutex_destroy(&wq->lock);
+	if (ret) {
+		err = -1;
+		pr_err("workqueue: error pthread_mutex_destroy: %s\n",
+			strerror(errno));
+	}
+
+	ret = pthread_cond_destroy(&wq->idle_cond);
+	if (ret) {
+		err = -1;
+		pr_err("workqueue: error pthread_cond_destroy: %s\n",
+			strerror(errno));
+	}
+
+	ret = close(wq->msg_pipe[0]);
+	if (ret) {
+		err = -1;
+		pr_err("workqueue: error close msg_pipe[0]: %s\n",
+			strerror(errno));
+	}
+
+	ret = close(wq->msg_pipe[1]);
+	if (ret) {
+		err = -1;
+		pr_err("workqueue: error close msg_pipe[1]: %s\n",
+			strerror(errno));
+	}
+
+	free(wq);
+
+	return err;
+}
+
+/**
+ * workqueue_nr_threads - get size of threadpool underlying @wq
+ */
+int workqueue_nr_threads(struct workqueue_struct *wq)
+{
+	return threadpool_size(wq->pool);
+}
diff --git a/tools/perf/util/workqueue/workqueue.h b/tools/perf/util/workqueue/workqueue.h
new file mode 100644
index 0000000000000000..86ec1d69274f41db
--- /dev/null
+++ b/tools/perf/util/workqueue/workqueue.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __WORKQUEUE_WORKQUEUE_H
+#define __WORKQUEUE_WORKQUEUE_H
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <linux/list.h>
+#include "threadpool.h"
+
+struct work_struct;
+typedef void (*work_func_t)(struct work_struct *work);
+
+struct work_struct {
+	struct list_head entry;
+	work_func_t func;
+};
+
+struct workqueue_struct;
+
+extern struct workqueue_struct *create_workqueue(struct threadpool_struct *pool);
+extern int destroy_workqueue(struct workqueue_struct *wq);
+
+extern int workqueue_nr_threads(struct workqueue_struct *wq);
+#endif /* __WORKQUEUE_WORKQUEUE_H */
-- 
2.31.1