[PATCH 4/5] ringbuffer: Test device

Kent Overstreet
2024-06-03T00:33:23Z

This adds /dev/ringbuffer-test, which supports reading and writing a
sequence of integers, to test performance and correctness.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/Makefile | 1 +
fs/ringbuffer_test.c | 209 +++++++++++++++++++++++++++++++++++++++++++
lib/Kconfig.debug | 5 ++
3 files changed, 215 insertions(+)
create mode 100644 fs/ringbuffer_test.c

diff --git a/fs/Makefile b/fs/Makefile
index 48e54ac01fb1..91061f281f0a 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_EVENTFD) += eventfd.o
obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
obj-$(CONFIG_AIO) += aio.o
obj-$(CONFIG_RINGBUFFER) += ringbuffer.o
+obj-$(CONFIG_RINGBUFFER_TEST) += ringbuffer_test.o
obj-$(CONFIG_FS_DAX) += dax.o
obj-$(CONFIG_FS_ENCRYPTION) += crypto/
obj-$(CONFIG_FS_VERITY) += verity/
diff --git a/fs/ringbuffer_test.c b/fs/ringbuffer_test.c
new file mode 100644
index 000000000000..01aa9c55120d
--- /dev/null
+++ b/fs/ringbuffer_test.c
@@ -0,0 +1,209 @@
+// 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);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 59b6765d86b8..bb16762af575 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2957,6 +2957,11 @@ config TEST_OBJPOOL

If unsure, say N.

+config RINGBUFFER_TEST
+ bool "Test driver for sys_ringbuffer"
+ default n
+ depends on RINGBUFFER
+
endif # RUNTIME_TESTING_MENU

config ARCH_USE_MEMTEST
--
2.45.1