linux-kernel - Re: [PATCH 2/2] uacce: add uacce module

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Message-ID: <20190815142021.GE23267@kroah.com>
Date:   Thu, 15 Aug 2019 16:20:21 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Zhangfei Gao <zhangfei.gao@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-accelerators@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, Kenneth Lee <liguozhu@...ilicon.com>,
        Zaibo Xu <xuzaibo@...wei.com>,
        Zhou Wang <wangzhou1@...ilicon.com>
Subject: Re: [PATCH 2/2] uacce: add uacce module

On Wed, Aug 14, 2019 at 05:34:25PM +0800, Zhangfei Gao wrote:
> +/* lock to protect all queues management */
> +static DECLARE_RWSEM(uacce_qs_lock);
> +#define uacce_qs_rlock() down_read(&uacce_qs_lock)
> +#define uacce_qs_runlock() up_read(&uacce_qs_lock)
> +#define uacce_qs_wlock() down_write(&uacce_qs_lock)
> +#define uacce_qs_wunlock() up_write(&uacce_qs_lock)

Do not define your own locking macros.  That makes the code impossible
to review.

And are you _sure_ you need a rw lock?  You have benchmarked where it
has a performance impact?

> +/**
> + * uacce_wake_up - Wake up the process who is waiting this queue
> + * @q the accelerator queue to wake up
> + */
> +void uacce_wake_up(struct uacce_queue *q)
> +{
> +	dev_dbg(&q->uacce->dev, "wake up\n");

ftrace is your friend, no need for any such logging lines anywhere in
these files.

> +	wake_up_interruptible(&q->wait);
> +}
> +EXPORT_SYMBOL_GPL(uacce_wake_up);

...

> +static struct attribute *uacce_dev_attrs[] = {
> +	&dev_attr_id.attr,
> +	&dev_attr_api.attr,
> +	&dev_attr_node_id.attr,
> +	&dev_attr_numa_distance.attr,
> +	&dev_attr_flags.attr,
> +	&dev_attr_available_instances.attr,
> +	&dev_attr_algorithms.attr,
> +	&dev_attr_qfrs_offset.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group uacce_dev_attr_group = {
> +	.name	= UACCE_DEV_ATTRS,
> +	.attrs	= uacce_dev_attrs,
> +};

Why is your attribute group in a subdirectory?  Why not in the "normal"
class directory?

You are adding sysfs files to the kernel without any Documentation/ABI/
entries, which is a requirement.  Please fix that up for the next time
you send these.

> +static const struct attribute_group *uacce_dev_attr_groups[] = {
> +	&uacce_dev_attr_group,
> +	NULL
> +};
> +
> +static int uacce_create_chrdev(struct uacce *uacce)
> +{
> +	int ret;
> +
> +	ret = idr_alloc(&uacce_idr, uacce, 0, 0, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +

Shouldn't this function create the memory needed for this structure?
You are relying ont he caller to do it for you, why?


> +	cdev_init(&uacce->cdev, &uacce_fops);
> +	uacce->dev_id = ret;
> +	uacce->cdev.owner = THIS_MODULE;
> +	device_initialize(&uacce->dev);
> +	uacce->dev.devt = MKDEV(MAJOR(uacce_devt), uacce->dev_id);
> +	uacce->dev.class = uacce_class;
> +	uacce->dev.groups = uacce_dev_attr_groups;
> +	uacce->dev.parent = uacce->pdev;
> +	dev_set_name(&uacce->dev, "%s-%d", uacce->drv_name, uacce->dev_id);
> +	ret = cdev_device_add(&uacce->cdev, &uacce->dev);
> +	if (ret)
> +		goto err_with_idr;
> +
> +	dev_dbg(&uacce->dev, "create uacce minior=%d\n", uacce->dev_id);
> +	return 0;
> +
> +err_with_idr:
> +	idr_remove(&uacce_idr, uacce->dev_id);
> +	return ret;
> +}
> +
> +static void uacce_destroy_chrdev(struct uacce *uacce)
> +{
> +	cdev_device_del(&uacce->cdev, &uacce->dev);
> +	idr_remove(&uacce_idr, uacce->dev_id);
> +}
> +
> +static int uacce_default_get_available_instances(struct uacce *uacce)
> +{
> +	return -1;

Do not make up error values, use the proper -EXXXX value instead.

> +}
> +
> +static int uacce_default_start_queue(struct uacce_queue *q)
> +{
> +	dev_dbg(&q->uacce->dev, "fake start queue");
> +	return 0;

Why even have this function if you do not do anything in it?

> +}
> +
> +static int uacce_dev_match(struct device *dev, void *data)
> +{
> +	if (dev->parent == data)
> +		return -EBUSY;

There should be in-kernel functions for this now, no need for you to
roll your own.

thanks,

greg k-h