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// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) "%s() " fmt "\n", __func__
#include <linux/device.h>
#include <linux/errname.h>
#include <linux/fs.h>
#include <linux/kthread.h>
#include <linux/ringbuffer_sys.h>
#include <linux/uio.h>
struct ringbuffer_test_file {
struct ringbuffer_test_rw {
struct mutex lock;
struct ringbuffer *rb;
struct task_struct *thr;
} rw[2];
};
#define BUF_NR 4
static int ringbuffer_test_writer(void *p)
{
struct file *file = p;
struct ringbuffer_test_file *f = file->private_data;
struct ringbuffer *rb = f->rw[READ].rb;
u32 idx = 0;
u32 buf[BUF_NR];
while (!kthread_should_stop()) {
cond_resched();
struct kvec vec = { buf, sizeof(buf) };
struct iov_iter iter;
iov_iter_kvec(&iter, ITER_SOURCE, &vec, 1, sizeof(buf));
for (unsigned i = 0; i < ARRAY_SIZE(buf); i++)
buf[i] = idx + i;
ssize_t ret = ringbuffer_write_iter(rb, &iter, false);
if (ret < 0)
continue;
idx += ret / sizeof(buf[0]);
}
return 0;
}
static int ringbuffer_test_reader(void *p)
{
struct file *file = p;
struct ringbuffer_test_file *f = file->private_data;
struct ringbuffer *rb = f->rw[WRITE].rb;
u32 idx = 0;
u32 buf[BUF_NR];
while (!kthread_should_stop()) {
cond_resched();
struct kvec vec = { buf, sizeof(buf) };
struct iov_iter iter;
iov_iter_kvec(&iter, ITER_DEST, &vec, 1, sizeof(buf));
ssize_t ret = ringbuffer_read_iter(rb, &iter, false);
if (ret < 0)
continue;
unsigned nr = ret / sizeof(buf[0]);
for (unsigned i = 0; i < nr; i++)
if (buf[i] != idx + i)
pr_err("read wrong data");
idx += ret / sizeof(buf[0]);
}
return 0;
}
static void ringbuffer_test_free(struct ringbuffer_test_file *f)
{
for (unsigned i = 0; i < ARRAY_SIZE(f->rw); i++)
if (!IS_ERR_OR_NULL(f->rw[i].thr))
kthread_stop_put(f->rw[i].thr);
for (unsigned i = 0; i < ARRAY_SIZE(f->rw); i++)
if (!IS_ERR_OR_NULL(f->rw[i].rb))
ringbuffer_free(f->rw[i].rb);
kfree(f);
}
static int ringbuffer_test_open(struct inode *inode, struct file *file)
{
static const char * const rw_str[] = { "reader", "writer" };
int ret = 0;
struct ringbuffer_test_file *f = kzalloc(sizeof(*f), GFP_KERNEL);
if (!f)
return -ENOMEM;
for (struct ringbuffer_test_rw *i = f->rw;
i < f->rw + ARRAY_SIZE(f->rw);
i++) {
unsigned idx = i - f->rw;
mutex_init(&i->lock);
i->rb = ringbuffer_alloc(PAGE_SIZE * 4);
ret = PTR_ERR_OR_ZERO(i->rb);
if (ret)
goto err;
i->thr = kthread_create(idx == READ
? ringbuffer_test_reader
: ringbuffer_test_writer,
file, "ringbuffer_%s", rw_str[idx]);
ret = PTR_ERR_OR_ZERO(i->thr);
if (ret)
goto err;
get_task_struct(i->thr);
}
file->private_data = f;
wake_up_process(f->rw[0].thr);
wake_up_process(f->rw[1].thr);
return 0;
err:
ringbuffer_test_free(f);
return ret;
}
static int ringbuffer_test_release(struct inode *inode, struct file *file)
{
ringbuffer_test_free(file->private_data);
return 0;
}
static ssize_t ringbuffer_test_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct ringbuffer_test_file *f = file->private_data;
struct ringbuffer_test_rw *i = &f->rw[READ];
ssize_t ret = mutex_lock_interruptible(&i->lock);
if (ret)
return ret;
ret = ringbuffer_read_iter(i->rb, iter, file->f_flags & O_NONBLOCK);
mutex_unlock(&i->lock);
return ret;
}
static ssize_t ringbuffer_test_write_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct ringbuffer_test_file *f = file->private_data;
struct ringbuffer_test_rw *i = &f->rw[WRITE];
ssize_t ret = mutex_lock_interruptible(&i->lock);
if (ret)
return ret;
ret = ringbuffer_write_iter(i->rb, iter, file->f_flags & O_NONBLOCK);
mutex_unlock(&i->lock);
return ret;
}
static struct ringbuffer *ringbuffer_test_ringbuffer(struct file *file, int rw)
{
struct ringbuffer_test_file *i = file->private_data;
BUG_ON(rw > WRITE);
return i->rw[rw].rb;
}
static const struct file_operations ringbuffer_fops = {
.owner = THIS_MODULE,
.read_iter = ringbuffer_test_read_iter,
.write_iter = ringbuffer_test_write_iter,
.ringbuffer = ringbuffer_test_ringbuffer,
.open = ringbuffer_test_open,
.release = ringbuffer_test_release,
};
static int __init ringbuffer_test_init(void)
{
int ringbuffer_major = register_chrdev(0, "ringbuffer-test", &ringbuffer_fops);
if (ringbuffer_major < 0)
return ringbuffer_major;
static const struct class ringbuffer_class = { .name = "ringbuffer_test" };
int ret = class_register(&ringbuffer_class);
if (ret)
goto major_out;
struct device *ringbuffer_device = device_create(&ringbuffer_class, NULL,
MKDEV(ringbuffer_major, 0),
NULL, "ringbuffer-test");
ret = PTR_ERR_OR_ZERO(ringbuffer_device);
if (ret)
goto class_out;
return 0;
class_out:
class_unregister(&ringbuffer_class);
major_out:
unregister_chrdev(ringbuffer_major, "ringbuffer-test");
return ret;
}
__initcall(ringbuffer_test_init);
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