// SPDX-License-Identifier: GPL-2.0

/*
 * Test module for lockless object pool
 *
 * Copyright: wuqiang.matt@bytedance.com
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/hrtimer.h>
#include <linux/objpool.h>

#define OT_NR_MAX_BULK (16)

/* memory usage */
struct ot_mem_stat {
	atomic_long_t alloc;
	atomic_long_t free;
};

/* object allocation results */
struct ot_obj_stat {
	unsigned long nhits;
	unsigned long nmiss;
};

/* control & results per testcase */
struct ot_data {
	struct rw_semaphore start;
	struct completion wait;
	struct completion rcu;
	atomic_t nthreads ____cacheline_aligned_in_smp;
	atomic_t stop ____cacheline_aligned_in_smp;
	struct ot_mem_stat kmalloc;
	struct ot_mem_stat vmalloc;
	struct ot_obj_stat objects;
	u64    duration;
};

/* testcase */
struct ot_test {
	int async; /* synchronous or asynchronous */
	int mode; /* only mode 0 supported */
	int objsz; /* object size */
	int duration; /* ms */
	int delay; /* ms */
	int bulk_normal;
	int bulk_irq;
	unsigned long hrtimer; /* ms */
	const char *name;
	struct ot_data data;
};

/* per-cpu worker */
struct ot_item {
	struct objpool_head *pool; /* pool head */
	struct ot_test *test; /* test parameters */

	void (*worker)(struct ot_item *item, int irq);

	/* hrtimer control */
	ktime_t hrtcycle;
	struct hrtimer hrtimer;

	int bulk[2]; /* for thread and irq */
	int delay;
	u32 niters;

	/* summary per thread */
	struct ot_obj_stat stat[2]; /* thread and irq */
	u64 duration;
};

/*
 * memory leakage checking
 */

static void *ot_kzalloc(struct ot_test *test, long size)
{
	void *ptr = kzalloc(size, GFP_KERNEL);

	if (ptr)
		atomic_long_add(size, &test->data.kmalloc.alloc);
	return ptr;
}

static void ot_kfree(struct ot_test *test, void *ptr, long size)
{
	if (!ptr)
		return;
	atomic_long_add(size, &test->data.kmalloc.free);
	kfree(ptr);
}

static void ot_mem_report(struct ot_test *test)
{
	long alloc, free;

	pr_info("memory allocation summary for %s\n", test->name);

	alloc = atomic_long_read(&test->data.kmalloc.alloc);
	free = atomic_long_read(&test->data.kmalloc.free);
	pr_info("  kmalloc: %lu - %lu = %lu\n", alloc, free, alloc - free);

	alloc = atomic_long_read(&test->data.vmalloc.alloc);
	free = atomic_long_read(&test->data.vmalloc.free);
	pr_info("  vmalloc: %lu - %lu = %lu\n", alloc, free, alloc - free);
}

/* user object instance */
struct ot_node {
	void *owner;
	unsigned long data;
	unsigned long refs;
	unsigned long payload[32];
};

/* user objpool manager */
struct ot_context {
	struct objpool_head pool; /* objpool head */
	struct ot_test *test; /* test parameters */
	void *ptr; /* user pool buffer */
	unsigned long size; /* buffer size */
	struct rcu_head rcu;
};

static DEFINE_PER_CPU(struct ot_item, ot_pcup_items);

static int ot_init_data(struct ot_data *data)
{
	memset(data, 0, sizeof(*data));
	init_rwsem(&data->start);
	init_completion(&data->wait);
	init_completion(&data->rcu);
	atomic_set(&data->nthreads, 1);

	return 0;
}

static int ot_init_node(void *nod, void *context)
{
	struct ot_context *sop = context;
	struct ot_node *on = nod;

	on->owner = &sop->pool;
	return 0;
}

static enum hrtimer_restart ot_hrtimer_handler(struct hrtimer *hrt)
{
	struct ot_item *item = container_of(hrt, struct ot_item, hrtimer);
	struct ot_test *test = item->test;

	if (atomic_read_acquire(&test->data.stop))
		return HRTIMER_NORESTART;

	/* do bulk-testings for objects pop/push */
	item->worker(item, 1);

	hrtimer_forward(hrt, hrt->base->get_time(), item->hrtcycle);
	return HRTIMER_RESTART;
}

static void ot_start_hrtimer(struct ot_item *item)
{
	if (!item->test->hrtimer)
		return;
	hrtimer_start(&item->hrtimer, item->hrtcycle, HRTIMER_MODE_REL);
}

static void ot_stop_hrtimer(struct ot_item *item)
{
	if (!item->test->hrtimer)
		return;
	hrtimer_cancel(&item->hrtimer);
}

static int ot_init_hrtimer(struct ot_item *item, unsigned long hrtimer)
{
	struct hrtimer *hrt = &item->hrtimer;

	if (!hrtimer)
		return -ENOENT;

	item->hrtcycle = ktime_set(0, hrtimer * 1000000UL);
	hrtimer_init(hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	hrt->function = ot_hrtimer_handler;
	return 0;
}

static int ot_init_cpu_item(struct ot_item *item,
			struct ot_test *test,
			struct objpool_head *pool,
			void (*worker)(struct ot_item *, int))
{
	memset(item, 0, sizeof(*item));
	item->pool = pool;
	item->test = test;
	item->worker = worker;

	item->bulk[0] = test->bulk_normal;
	item->bulk[1] = test->bulk_irq;
	item->delay = test->delay;

	/* initialize hrtimer */
	ot_init_hrtimer(item, item->test->hrtimer);
	return 0;
}

static int ot_thread_worker(void *arg)
{
	struct ot_item *item = arg;
	struct ot_test *test = item->test;
	ktime_t start;

	atomic_inc(&test->data.nthreads);
	down_read(&test->data.start);
	up_read(&test->data.start);
	start = ktime_get();
	ot_start_hrtimer(item);
	do {
		if (atomic_read_acquire(&test->data.stop))
			break;
		/* do bulk-testings for objects pop/push */
		item->worker(item, 0);
	} while (!kthread_should_stop());
	ot_stop_hrtimer(item);
	item->duration = (u64) ktime_us_delta(ktime_get(), start);
	if (atomic_dec_and_test(&test->data.nthreads))
		complete(&test->data.wait);

	return 0;
}

static void ot_perf_report(struct ot_test *test, u64 duration)
{
	struct ot_obj_stat total, normal = {0}, irq = {0};
	int cpu, nthreads = 0;

	pr_info("\n");
	pr_info("Testing summary for %s\n", test->name);

	for_each_possible_cpu(cpu) {
		struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
		if (!item->duration)
			continue;
		normal.nhits += item->stat[0].nhits;
		normal.nmiss += item->stat[0].nmiss;
		irq.nhits += item->stat[1].nhits;
		irq.nmiss += item->stat[1].nmiss;
		pr_info("CPU: %d  duration: %lluus\n", cpu, item->duration);
		pr_info("\tthread:\t%16lu hits \t%16lu miss\n",
			item->stat[0].nhits, item->stat[0].nmiss);
		pr_info("\tirq:   \t%16lu hits \t%16lu miss\n",
			item->stat[1].nhits, item->stat[1].nmiss);
		pr_info("\ttotal: \t%16lu hits \t%16lu miss\n",
			item->stat[0].nhits + item->stat[1].nhits,
			item->stat[0].nmiss + item->stat[1].nmiss);
		nthreads++;
	}

	total.nhits = normal.nhits + irq.nhits;
	total.nmiss = normal.nmiss + irq.nmiss;

	pr_info("ALL: \tnthreads: %d  duration: %lluus\n", nthreads, duration);
	pr_info("SUM: \t%16lu hits \t%16lu miss\n",
		total.nhits, total.nmiss);

	test->data.objects = total;
	test->data.duration = duration;
}

/*
 * synchronous test cases for objpool manipulation
 */

/* objpool manipulation for synchronous mode (percpu objpool) */
static struct ot_context *ot_init_sync_m0(struct ot_test *test)
{
	struct ot_context *sop = NULL;
	int max = num_possible_cpus() << 3;
	gfp_t gfp = GFP_KERNEL;

	sop = (struct ot_context *)ot_kzalloc(test, sizeof(*sop));
	if (!sop)
		return NULL;
	sop->test = test;
	if (test->objsz < 512)
		gfp = GFP_ATOMIC;

	if (objpool_init(&sop->pool, max, test->objsz,
			 gfp, sop, ot_init_node, NULL)) {
		ot_kfree(test, sop, sizeof(*sop));
		return NULL;
	}
	WARN_ON(max != sop->pool.nr_objs);

	return sop;
}

static void ot_fini_sync(struct ot_context *sop)
{
	objpool_fini(&sop->pool);
	ot_kfree(sop->test, sop, sizeof(*sop));
}

static struct {
	struct ot_context * (*init)(struct ot_test *oc);
	void (*fini)(struct ot_context *sop);
} g_ot_sync_ops[] = {
	{.init = ot_init_sync_m0, .fini = ot_fini_sync},
};

/*
 * synchronous test cases: performance mode
 */

static void ot_bulk_sync(struct ot_item *item, int irq)
{
	struct ot_node *nods[OT_NR_MAX_BULK];
	int i;

	for (i = 0; i < item->bulk[irq]; i++)
		nods[i] = objpool_pop(item->pool);

	if (!irq && (item->delay || !(++(item->niters) & 0x7FFF)))
		msleep(item->delay);

	while (i-- > 0) {
		struct ot_node *on = nods[i];
		if (on) {
			on->refs++;
			objpool_push(on, item->pool);
			item->stat[irq].nhits++;
		} else {
			item->stat[irq].nmiss++;
		}
	}
}

static int ot_start_sync(struct ot_test *test)
{
	struct ot_context *sop;
	ktime_t start;
	u64 duration;
	unsigned long timeout;
	int cpu;

	/* initialize objpool for syncrhonous testcase */
	sop = g_ot_sync_ops[test->mode].init(test);
	if (!sop)
		return -ENOMEM;

	/* grab rwsem to block testing threads */
	down_write(&test->data.start);

	for_each_possible_cpu(cpu) {
		struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
		struct task_struct *work;

		ot_init_cpu_item(item, test, &sop->pool, ot_bulk_sync);

		/* skip offline cpus */
		if (!cpu_online(cpu))
			continue;

		work = kthread_create_on_node(ot_thread_worker, item,
				cpu_to_node(cpu), "ot_worker_%d", cpu);
		if (IS_ERR(work)) {
			pr_err("failed to create thread for cpu %d\n", cpu);
		} else {
			kthread_bind(work, cpu);
			wake_up_process(work);
		}
	}

	/* wait a while to make sure all threads waiting at start line */
	msleep(20);

	/* in case no threads were created: memory insufficient ? */
	if (atomic_dec_and_test(&test->data.nthreads))
		complete(&test->data.wait);

	// sched_set_fifo_low(current);

	/* start objpool testing threads */
	start = ktime_get();
	up_write(&test->data.start);

	/* yeild cpu to worker threads for duration ms */
	timeout = msecs_to_jiffies(test->duration);
	schedule_timeout_interruptible(timeout);

	/* tell workers threads to quit */
	atomic_set_release(&test->data.stop, 1);

	/* wait all workers threads finish and quit */
	wait_for_completion(&test->data.wait);
	duration = (u64) ktime_us_delta(ktime_get(), start);

	/* cleanup objpool */
	g_ot_sync_ops[test->mode].fini(sop);

	/* report testing summary and performance results */
	ot_perf_report(test, duration);

	/* report memory allocation summary */
	ot_mem_report(test);

	return 0;
}

/*
 * asynchronous test cases: pool lifecycle controlled by refcount
 */

static void ot_fini_async_rcu(struct rcu_head *rcu)
{
	struct ot_context *sop = container_of(rcu, struct ot_context, rcu);
	struct ot_test *test = sop->test;

	/* here all cpus are aware of the stop event: test->data.stop = 1 */
	WARN_ON(!atomic_read_acquire(&test->data.stop));

	objpool_fini(&sop->pool);
	complete(&test->data.rcu);
}

static void ot_fini_async(struct ot_context *sop)
{
	/* make sure the stop event is acknowledged by all cores */
	call_rcu(&sop->rcu, ot_fini_async_rcu);
}

static int ot_objpool_release(struct objpool_head *head, void *context)
{
	struct ot_context *sop = context;

	WARN_ON(!head || !sop || head != &sop->pool);

	/* do context cleaning if needed */
	if (sop)
		ot_kfree(sop->test, sop, sizeof(*sop));

	return 0;
}

static struct ot_context *ot_init_async_m0(struct ot_test *test)
{
	struct ot_context *sop = NULL;
	int max = num_possible_cpus() << 3;
	gfp_t gfp = GFP_KERNEL;

	sop = (struct ot_context *)ot_kzalloc(test, sizeof(*sop));
	if (!sop)
		return NULL;
	sop->test = test;
	if (test->objsz < 512)
		gfp = GFP_ATOMIC;

	if (objpool_init(&sop->pool, max, test->objsz, gfp, sop,
			 ot_init_node, ot_objpool_release)) {
		ot_kfree(test, sop, sizeof(*sop));
		return NULL;
	}
	WARN_ON(max != sop->pool.nr_objs);

	return sop;
}

static struct {
	struct ot_context * (*init)(struct ot_test *oc);
	void (*fini)(struct ot_context *sop);
} g_ot_async_ops[] = {
	{.init = ot_init_async_m0, .fini = ot_fini_async},
};

static void ot_nod_recycle(struct ot_node *on, struct objpool_head *pool,
			int release)
{
	struct ot_context *sop;

	on->refs++;

	if (!release) {
		/* push object back to opjpool for reuse */
		objpool_push(on, pool);
		return;
	}

	sop = container_of(pool, struct ot_context, pool);
	WARN_ON(sop != pool->context);

	/* unref objpool with nod removed forever */
	objpool_drop(on, pool);
}

static void ot_bulk_async(struct ot_item *item, int irq)
{
	struct ot_test *test = item->test;
	struct ot_node *nods[OT_NR_MAX_BULK];
	int i, stop;

	for (i = 0; i < item->bulk[irq]; i++)
		nods[i] = objpool_pop(item->pool);

	if (!irq) {
		if (item->delay || !(++(item->niters) & 0x7FFF))
			msleep(item->delay);
		get_cpu();
	}

	stop = atomic_read_acquire(&test->data.stop);

	/* drop all objects and deref objpool */
	while (i-- > 0) {
		struct ot_node *on = nods[i];

		if (on) {
			on->refs++;
			ot_nod_recycle(on, item->pool, stop);
			item->stat[irq].nhits++;
		} else {
			item->stat[irq].nmiss++;
		}
	}

	if (!irq)
		put_cpu();
}

static int ot_start_async(struct ot_test *test)
{
	struct ot_context *sop;
	ktime_t start;
	u64 duration;
	unsigned long timeout;
	int cpu;

	/* initialize objpool for syncrhonous testcase */
	sop = g_ot_async_ops[test->mode].init(test);
	if (!sop)
		return -ENOMEM;

	/* grab rwsem to block testing threads */
	down_write(&test->data.start);

	for_each_possible_cpu(cpu) {
		struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
		struct task_struct *work;

		ot_init_cpu_item(item, test, &sop->pool, ot_bulk_async);

		/* skip offline cpus */
		if (!cpu_online(cpu))
			continue;

		work = kthread_create_on_node(ot_thread_worker, item,
				cpu_to_node(cpu), "ot_worker_%d", cpu);
		if (IS_ERR(work)) {
			pr_err("failed to create thread for cpu %d\n", cpu);
		} else {
			kthread_bind(work, cpu);
			wake_up_process(work);
		}
	}

	/* wait a while to make sure all threads waiting at start line */
	msleep(20);

	/* in case no threads were created: memory insufficient ? */
	if (atomic_dec_and_test(&test->data.nthreads))
		complete(&test->data.wait);

	/* start objpool testing threads */
	start = ktime_get();
	up_write(&test->data.start);

	/* yeild cpu to worker threads for duration ms */
	timeout = msecs_to_jiffies(test->duration);
	schedule_timeout_interruptible(timeout);

	/* tell workers threads to quit */
	atomic_set_release(&test->data.stop, 1);

	/* do async-finalization */
	g_ot_async_ops[test->mode].fini(sop);

	/* wait all workers threads finish and quit */
	wait_for_completion(&test->data.wait);
	duration = (u64) ktime_us_delta(ktime_get(), start);

	/* assure rcu callback is triggered */
	wait_for_completion(&test->data.rcu);

	/*
	 * now we are sure that objpool is finalized either
	 * by rcu callback or by worker threads
	 */

	/* report testing summary and performance results */
	ot_perf_report(test, duration);

	/* report memory allocation summary */
	ot_mem_report(test);

	return 0;
}

/*
 * predefined testing cases:
 *   synchronous case / overrun case / async case
 *
 * async: synchronous or asynchronous testing
 * mode: only mode 0 supported
 * objsz: object size
 * duration: int, total test time in ms
 * delay: int, delay (in ms) between each iteration
 * bulk_normal: int, repeat times for thread worker
 * bulk_irq: int, repeat times for irq consumer
 * hrtimer: unsigned long, hrtimer intervnal in ms
 * name: char *, tag for current test ot_item
 */

#define NODE_COMPACT sizeof(struct ot_node)
#define NODE_VMALLOC (512)

static struct ot_test g_testcases[] = {

	/* sync & normal */
	{0, 0, NODE_COMPACT, 1000, 0,  1,  0,  0, "sync: percpu objpool"},
	{0, 0, NODE_VMALLOC, 1000, 0,  1,  0,  0, "sync: percpu objpool from vmalloc"},

	/* sync & hrtimer */
	{0, 0, NODE_COMPACT, 1000, 0,  1,  1,  4, "sync & hrtimer: percpu objpool"},
	{0, 0, NODE_VMALLOC, 1000, 0,  1,  1,  4, "sync & hrtimer: percpu objpool from vmalloc"},

	/* sync & overrun */
	{0, 0, NODE_COMPACT, 1000, 0, 16,  0,  0, "sync overrun: percpu objpool"},
	{0, 0, NODE_VMALLOC, 1000, 0, 16,  0,  0, "sync overrun: percpu objpool from vmalloc"},

	/* async mode */
	{1, 0, NODE_COMPACT, 1000, 100,  1,  0,  0, "async: percpu objpool"},
	{1, 0, NODE_VMALLOC, 1000, 100,  1,  0,  0, "async: percpu objpool from vmalloc"},

	/* async + hrtimer mode */
	{1, 0, NODE_COMPACT, 1000, 0,  4,  4,  4, "async & hrtimer: percpu objpool"},
	{1, 0, NODE_VMALLOC, 1000, 0,  4,  4,  4, "async & hrtimer: percpu objpool from vmalloc"},
};

static int __init ot_mod_init(void)
{
	int i;

	/* perform testings */
	for (i = 0; i < ARRAY_SIZE(g_testcases); i++) {
		ot_init_data(&g_testcases[i].data);
		if (g_testcases[i].async)
			ot_start_async(&g_testcases[i]);
		else
			ot_start_sync(&g_testcases[i]);
	}

	/* show tests summary */
	pr_info("\n");
	pr_info("Summary of testcases:\n");
	for (i = 0; i < ARRAY_SIZE(g_testcases); i++) {
		pr_info("    duration: %lluus \thits: %10lu \tmiss: %10lu \t%s\n",
			g_testcases[i].data.duration, g_testcases[i].data.objects.nhits,
			g_testcases[i].data.objects.nmiss, g_testcases[i].name);
	}

	return -EAGAIN;
}

static void __exit ot_mod_exit(void)
{
}

module_init(ot_mod_init);
module_exit(ot_mod_exit);

MODULE_DESCRIPTION("Test module for lockless object pool");
MODULE_LICENSE("GPL");