[RFC PATCH v2 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          |  86 +++++++++
 tools/perf/util/workqueue/Build       |   1 +
 tools/perf/util/workqueue/workqueue.c | 268 ++++++++++++++++++++++++++
 tools/perf/util/workqueue/workqueue.h |  38 ++++
 4 files changed, 393 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 87bf8fc71c346653..2165a563e47bd6a5 100644
--- a/tools/perf/tests/workqueue.c
+++ b/tools/perf/tests/workqueue.c
@@ -6,6 +6,7 @@
 #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
@@ -14,6 +15,11 @@ 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;
@@ -141,6 +147,52 @@ static int __test__threadpool(void *_args)
 	return ret;
 }
 
+
+static int __workqueue__prepare(struct threadpool **pool,
+				struct workqueue_struct **wq,
+				int pool_size)
+{
+	int ret = __threadpool__prepare(pool, pool_size);
+
+	if (ret)
+		return ret;
+
+	*wq = create_workqueue(*pool);
+	TEST_ASSERT_VAL("workqueue creation failure", !IS_ERR(*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 TEST_OK;
+}
+
+static int __workqueue__teardown(struct threadpool *pool,
+				struct workqueue_struct *wq)
+{
+	int ret = destroy_workqueue(wq);
+
+	TEST_ASSERT_VAL("workqueue detruction failure", ret == 0);
+
+	return __threadpool__teardown(pool);
+}
+
+static int __test__workqueue(void *_args)
+{
+	struct workqueue_test_args_t *args = _args;
+	struct threadpool *pool;
+	struct workqueue_struct *wq;
+	int ret = __workqueue__prepare(&pool, &wq, args->pool_size);
+
+	if (ret)
+		goto out;
+
+	ret = __workqueue__teardown(pool, wq);
+	if (ret)
+		goto out;
+
+out:
+	return ret;
+}
+
 static const struct threadpool_test_args_t threadpool_test_args[] = {
 	{
 		.pool_size = 1
@@ -159,6 +211,33 @@ 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);
@@ -174,6 +253,13 @@ 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..d3c6d4c4e75944a5
--- /dev/null
+++ b/tools/perf/util/workqueue/workqueue.c
@@ -0,0 +1,268 @@
+// 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 <linux/err.h>
+#include <linux/string.h>
+#include "debug.h"
+#include <internal/lib.h>
+#include "workqueue.h"
+
+enum workqueue_status {
+	WORKQUEUE_STATUS__READY,	/* wq is ready to receive work */
+	WORKQUEUE_STATUS__ERROR,
+	WORKQUEUE_STATUS__MAX
+};
+
+static const char * const workqueue_status_tags[] = {
+	"ready",
+	"error"
+};
+
+struct workqueue_struct {
+	pthread_mutex_t		lock;		/* locking of the thread_pool */
+	pthread_cond_t		idle_cond;	/* all workers are idle cond */
+	struct threadpool	*pool;		/* underlying pool */
+	int			pool_errno;	/* latest pool error */
+	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;
+};
+
+static const char * const workqueue_errno_str[] = {
+	"",
+	"This operation is not allowed in this workqueue status",
+	"Error executing function in threadpool",
+	"Error waiting the threadpool",
+	"Error sending message to worker",
+	"Error receiving message from worker",
+	"Received unexpected message from worker",
+};
+
+/**
+ * worker_thread - worker function executed on threadpool
+ */
+static void worker_thread(int tidx, struct task_struct *task)
+{
+
+	pr_info("Hi from worker %d, executing task %p\n", tidx, task);
+}
+
+/**
+ * attach_threadpool_to_workqueue - start @wq workers on @pool
+ */
+static int attach_threadpool_to_workqueue(struct workqueue_struct *wq,
+					struct threadpool *pool)
+{
+	if (!threadpool__is_ready(pool)) {
+		pr_debug2("workqueue: cannot attach to pool: pool is not ready\n");
+		return -WORKQUEUE_ERROR__NOTALLOWED;
+	}
+
+	wq->pool = pool;
+
+	wq->pool_errno = threadpool__execute(pool, &wq->task);
+	if (wq->pool_errno)
+		return -WORKQUEUE_ERROR__POOLEXE;
+
+	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_debug2("workqueue: cannot attach to pool: wq is not ready\n");
+		return -WORKQUEUE_ERROR__NOTALLOWED;
+	}
+
+	ret = threadpool__wait(wq->pool);
+	if (ret) {
+		pr_debug2("workqueue: error waiting threadpool\n");
+		wq->pool_errno = ret;
+		err = -WORKQUEUE_ERROR__POOLWAIT;
+	}
+
+	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 *pool)
+{
+	int ret, err = 0;
+	struct workqueue_struct *wq = malloc(sizeof(struct workqueue_struct));
+
+	if (!wq) {
+		err = -ENOMEM;
+		goto out_return;
+	}
+
+	ret = pthread_mutex_init(&wq->lock, NULL);
+	if (ret) {
+		err = -ret;
+		goto out_free_wq;
+	}
+
+	ret = pthread_cond_init(&wq->idle_cond, NULL);
+	if (ret) {
+		err = -ret;
+		goto out_destroy_mutex;
+	}
+
+	wq->pool = NULL;
+	INIT_LIST_HEAD(&wq->busy_list);
+	INIT_LIST_HEAD(&wq->idle_list);
+
+	INIT_LIST_HEAD(&wq->pending);
+
+	ret = pipe(wq->msg_pipe);
+	if (ret) {
+		err = -ENOMEM;
+		goto out_destroy_cond;
+	}
+
+	wq->task.fn = worker_thread;
+
+	ret = attach_threadpool_to_workqueue(wq, pool);
+	if (ret) {
+		err = ret;
+		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);
+out_return:
+	return ERR_PTR(err);
+}
+
+/**
+ * destroy_workqueue - stop @wq workers and destroy @wq
+ */
+int destroy_workqueue(struct workqueue_struct *wq)
+{
+	int err = 0, ret;
+
+	if (IS_ERR_OR_NULL(wq))
+		return 0;
+
+	ret = detach_threadpool_from_workqueue(wq);
+	if (ret) {
+		pr_debug2("workqueue: error detaching from threadpool.\n");
+		err = ret;
+	}
+
+	ret = pthread_mutex_destroy(&wq->lock);
+	if (ret) {
+		err = -ret;
+		pr_debug2("workqueue: error pthread_mutex_destroy: %s\n",
+			strerror(errno));
+	}
+
+	ret = pthread_cond_destroy(&wq->idle_cond);
+	if (ret) {
+		err = -ret;
+		pr_debug2("workqueue: error pthread_cond_destroy: %s\n",
+			strerror(errno));
+	}
+
+	close(wq->msg_pipe[0]);
+	wq->msg_pipe[0] = -1;
+
+	close(wq->msg_pipe[1]);
+	wq->msg_pipe[1] = -1;
+
+	free(wq);
+	return err;
+}
+
+/**
+ * workqueue_strerror - print message regarding lastest error in @wq
+ *
+ * Buffer size should be at least WORKQUEUE_STRERR_BUFSIZE bytes.
+ */
+int workqueue_strerror(struct workqueue_struct *wq, int err, char *buf, size_t size)
+{
+	int ret;
+	char sbuf[THREADPOOL_STRERR_BUFSIZE], *emsg;
+	const char *status_str, *errno_str;
+
+	status_str = IS_ERR_OR_NULL(wq) ? "error" : workqueue_status_tags[wq->status];
+	errno_str = workqueue_errno_str[-err-WORKQUEUE_ERROR__OFFSET];
+
+	switch (err) {
+	case -WORKQUEUE_ERROR__NOTALLOWED:
+		return scnprintf(buf, size, "%s (%s).\n",
+			errno_str, status_str);
+	case -WORKQUEUE_ERROR__POOLEXE:
+	case -WORKQUEUE_ERROR__POOLWAIT:
+		if (IS_ERR_OR_NULL(wq))
+			return scnprintf(buf, size, "%s: unknown.\n",
+				errno_str);
+
+		ret = threadpool__strerror(wq->pool, wq->pool_errno, sbuf, sizeof(sbuf));
+		if (ret < 0)
+			return ret;
+		return scnprintf(buf, size, "%s: %s.\n", errno_str, sbuf);
+	case -WORKQUEUE_ERROR__WRITEPIPE:
+	case -WORKQUEUE_ERROR__READPIPE:
+		emsg = str_error_r(errno, sbuf, sizeof(sbuf));
+		return scnprintf(buf, size, "%s: %s.\n", errno_str, emsg);
+	case -WORKQUEUE_ERROR__INVALIDMSG:
+		return scnprintf(buf, size, "%s.\n", errno_str);
+	default:
+		emsg = str_error_r(err, sbuf, sizeof(sbuf));
+		return scnprintf(buf, size, "Error: %s", emsg);
+	}
+}
+
+/**
+ * create_workqueue_strerror - print message regarding @err_ptr
+ *
+ * Buffer size should be at least WORKQUEUE_STRERR_BUFSIZE bytes.
+ */
+int create_workqueue_strerror(struct workqueue_struct *err_ptr, char *buf, size_t size)
+{
+	return workqueue_strerror(err_ptr, PTR_ERR(err_ptr), buf, size);
+}
+
+/**
+ * destroy_workqueue_strerror - print message regarding @err
+ *
+ * Buffer size should be at least WORKQUEUE_STRERR_BUFSIZE bytes.
+ */
+int destroy_workqueue_strerror(int err, char *buf, size_t size)
+{
+	return workqueue_strerror(NULL, err, buf, size);
+}
+
+/**
+ * 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..456cd8b6cb2a26d8
--- /dev/null
+++ b/tools/perf/util/workqueue/workqueue.h
@@ -0,0 +1,38 @@
+/* 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 *pool);
+extern int destroy_workqueue(struct workqueue_struct *wq);
+
+extern int workqueue_nr_threads(struct workqueue_struct *wq);
+
+#define WORKQUEUE_STRERR_BUFSIZE (128+THREADPOOL_STRERR_BUFSIZE)
+#define WORKQUEUE_ERROR__OFFSET 512
+enum {
+	WORKQUEUE_ERROR__NOTALLOWED = WORKQUEUE_ERROR__OFFSET,
+	WORKQUEUE_ERROR__POOLEXE,
+	WORKQUEUE_ERROR__POOLWAIT,
+	WORKQUEUE_ERROR__WRITEPIPE,
+	WORKQUEUE_ERROR__READPIPE,
+	WORKQUEUE_ERROR__INVALIDMSG,
+};
+extern int workqueue_strerror(struct workqueue_struct *wq, int err, char *buf, size_t size);
+extern int create_workqueue_strerror(struct workqueue_struct *err_ptr, char *buf, size_t size);
+extern int destroy_workqueue_strerror(int err, char *buf, size_t size);
+#endif /* __WORKQUEUE_WORKQUEUE_H */
-- 
2.31.1