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/*
* Wound/Wait Mutex testing module.
* Copyright (C) 2016-2018 VMWare Inc.
*/
#include "ww_mutex_test.h"
#ifdef WW_BUILTIN
#include <linux/ww_mutex.h>
#define ww_acquire_batch_begin(_a)
#define ww_acquire_batch_end(_a)
#else
#include "ww_mutex.h"
#endif
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/delay.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Thomas Hellström");
MODULE_DESCRIPTION("Test module for ww_mutex performance");
MODULE_VERSION("1.0.0");
struct ww_mutex_item {
struct ww_mutex mutex;
/* Align to a typical cache line */
u8 pad[64 - sizeof(struct ww_mutex) % 64];
};
struct wwt_device {
struct ww_mutex_item *locks;
int *used;
int num_locks;
};
struct wwt_thread {
struct wwt_device *dev;
struct ww_mutex **p_locks;
u8 *used;
int num_locks;
int thread;
u32 num_rollbacks;
struct work_struct work;
};
static struct wwt_device g_dev;
static struct wwt_thread threads[WWT_NUM_THREADS];
static DEFINE_WW_CLASS(wwt_class);
static void wwt_thread_rollback(struct wwt_thread *t, int upto)
{
while(upto--)
ww_mutex_unlock(t->p_locks[upto]);
t->num_rollbacks++;
}
static int wwt_thread_lock_sequence(struct wwt_thread *t)
{
struct ww_acquire_ctx ctx;
int ret = 0;
int i;
ww_acquire_init(&ctx, &wwt_class);
ww_acquire_batch_begin(&ctx);
restart:
for (i = 0; i < t->num_locks; ++i) {
ret = ww_mutex_lock(t->p_locks[i], &ctx);
if (ret) {
WARN_ON(i == 0);
wwt_thread_rollback(t, i);
if (ret == -EDEADLK) {
swap(t->p_locks[0], t->p_locks[i]);
goto restart;
} else
goto out_err;
}
}
ww_acquire_batch_end(&ctx);
ww_acquire_done(&ctx);
udelay(WWT_CS_UDELAY);
ww_acquire_batch_begin(&ctx);
wwt_thread_rollback(t, t->num_locks);
t->num_rollbacks--;
out_err:
ww_acquire_batch_end(&ctx);
ww_acquire_fini(&ctx);
return ret;
}
static void wwt_lock_work(struct work_struct *work) {
struct wwt_thread *t = container_of(work, struct wwt_thread, work);
int i, ret;
printk(KERN_INFO "thread %d: Starting work.\n", t->thread);
for (i = 0; i < WWT_NUM_SUB; ++i) {
ret = wwt_thread_lock_sequence(t);
if (ret)
break;
}
printk(KERN_INFO "thread %d; Fininshed with %u rollbacks. ret is %d\n",
t->thread, t->num_rollbacks, ret);
}
static int wwt_thread_setup(struct wwt_thread *t, int thread)
{
struct wwt_device *dev = &g_dev;
u32 idx;
int i;
t->dev = dev;
t->p_locks = vmalloc(WWT_NUM_T_LOCKS * sizeof(*t->p_locks));
t->num_rollbacks = 0;
t->thread = thread;
INIT_WORK(&t->work, wwt_lock_work);
#ifndef WWT_NO_SHARED
memset(dev->used, 0, dev->num_locks * sizeof(*dev->used));
#endif
if (!t->p_locks)
return -ENOMEM;
for (i = 0; i < WWT_NUM_T_LOCKS; ++i) {
get_random_bytes(&idx, sizeof(idx));
idx %= WWT_NUM_LOCKS;
while(dev->used[idx]) {
idx++;
idx %= WWT_NUM_LOCKS;
}
dev->used[idx] = 1;
t->p_locks[i] = &dev->locks[idx].mutex;
}
t->num_locks = WWT_NUM_T_LOCKS;
return 0;
}
static void wwt_thread_destroy(struct wwt_thread *t)
{
cancel_work_sync(&t->work);
if (t->p_locks)
vfree(t->p_locks);
}
static void wwt_device_fini(struct wwt_device *wdev)
{
int i;
if (wdev->used)
vfree(wdev->used);
for (i = 0; i < ARRAY_SIZE(threads); ++i)
wwt_thread_destroy(&threads[i]);
for (i = 0; i < wdev->num_locks; ++i)
ww_mutex_destroy(&wdev->locks[i].mutex);
vfree(wdev->locks);
wdev->num_locks = 0;
}
static int wwt_device_init(struct wwt_device *wdev, int num_locks)
{
int i, ret;
wdev->num_locks = 0;
wdev->locks = vzalloc(num_locks * sizeof(*wdev->locks));
if (!wdev->locks)
return -ENOMEM;
wdev->used = vzalloc(num_locks * sizeof(*wdev->used));
if (!wdev->locks)
goto out_thread_setup;
for (i = 0; i < num_locks; ++i)
ww_mutex_init(&wdev->locks[i].mutex, &wwt_class);
wdev->num_locks = num_locks;
printk(KERN_INFO "Allocated %d mutexes. Alignment is %lu %lu\n",
num_locks, ((unsigned long) wdev->locks) % 64,
sizeof(struct ww_mutex));
for (i = 0; i < ARRAY_SIZE(threads); ++i) {
ret = wwt_thread_setup(&threads[i], i);
if (ret)
goto out_thread_setup;
}
printk(KERN_INFO "Set up %lu threads\n", ARRAY_SIZE(threads));
usleep_range(10000, 20000);
for (i = 0; i < ARRAY_SIZE(threads); ++i) {
#ifndef WWT_SEQUENTIAL
queue_work(system_unbound_wq, &threads[i].work);
#else
wwt_lock_work(&threads[i].work);
#endif
}
return 0;
out_thread_setup:
wwt_device_fini(&g_dev);
return ret;
}
static int __init wwt_init(void) {
printk(KERN_INFO "Hello, World!\n");
return wwt_device_init(&g_dev, WWT_NUM_LOCKS);
}
static void __exit wwt_exit(void) {
wwt_device_fini(&g_dev);
printk(KERN_INFO "Goodbye, World!\n");
}
module_init(wwt_init);
module_exit(wwt_exit);
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