Re: [PATCH v8 1/3] uacce: supports device isolation feature

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Sep 02, 2022 at 03:13:02AM +0000, Kai Ye wrote:
> UACCE adds the hardware error isolation API. Users can configure
> the isolation frequency by this sysfs node. UACCE reports the device
> isolate state to the user space. If the AER error frequency exceeds
> the value of setting for a certain period of time, the device will be
> isolated.
> 
> Signed-off-by: Kai Ye <yekai13@huawei.com>
> ---
>  drivers/misc/uacce/uacce.c | 58 ++++++++++++++++++++++++++++++++++++++
>  include/linux/uacce.h      | 11 ++++++++
>  2 files changed, 69 insertions(+)
> 
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index 281c54003edc..41f454c89cd1 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -7,6 +7,8 @@
>  #include <linux/slab.h>
>  #include <linux/uacce.h>
>  
> +#define MAX_ERR_ISOLATE_COUNT		65535

What units is this in?  Shouldn't this be in a .h file somewhere as it
is a limit you impose on a driver implementing this API.

> +
>  static struct class *uacce_class;
>  static dev_t uacce_devt;
>  static DEFINE_MUTEX(uacce_mutex);
> @@ -339,12 +341,57 @@ static ssize_t region_dus_size_show(struct device *dev,
>  		       uacce->qf_pg_num[UACCE_QFRT_DUS] << PAGE_SHIFT);
>  }
>  
> +static ssize_t isolate_show(struct device *dev,
> +			    struct device_attribute *attr, char *buf)
> +{
> +	struct uacce_device *uacce = to_uacce_device(dev);
> +
> +	if (!uacce->ops->get_isolate_state)
> +		return -ENODEV;
> +
> +	return sysfs_emit(buf, "%d\n", uacce->ops->get_isolate_state(uacce));
> +}
> +
> +static ssize_t isolate_strategy_show(struct device *dev,
> +				     struct device_attribute *attr, char *buf)
> +{
> +	struct uacce_device *uacce = to_uacce_device(dev);
> +	u32 val;
> +
> +	val = uacce->ops->isolate_strategy_read(uacce);
> +	if (val > MAX_ERR_ISOLATE_COUNT)
> +		return -EINVAL;

How can a driver return a higher number here?

> +
> +	return sysfs_emit(buf, "%u\n", val);
> +}
> +
> +static ssize_t isolate_strategy_store(struct device *dev,
> +				      struct device_attribute *attr,
> +				      const char *buf, size_t count)
> +{
> +	struct uacce_device *uacce = to_uacce_device(dev);
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 0, &val) < 0)
> +		return -EINVAL;
> +
> +	if (val > MAX_ERR_ISOLATE_COUNT)
> +		return -EINVAL;
> +
> +	ret = uacce->ops->isolate_strategy_write(uacce, val);
> +
> +	return ret ? ret : count;

Please write out if statements.

> +}
> +
>  static DEVICE_ATTR_RO(api);
>  static DEVICE_ATTR_RO(flags);
>  static DEVICE_ATTR_RO(available_instances);
>  static DEVICE_ATTR_RO(algorithms);
>  static DEVICE_ATTR_RO(region_mmio_size);
>  static DEVICE_ATTR_RO(region_dus_size);
> +static DEVICE_ATTR_RO(isolate);
> +static DEVICE_ATTR_RW(isolate_strategy);
>  
>  static struct attribute *uacce_dev_attrs[] = {
>  	&dev_attr_api.attr,
> @@ -353,6 +400,8 @@ static struct attribute *uacce_dev_attrs[] = {
>  	&dev_attr_algorithms.attr,
>  	&dev_attr_region_mmio_size.attr,
>  	&dev_attr_region_dus_size.attr,
> +	&dev_attr_isolate.attr,
> +	&dev_attr_isolate_strategy.attr,
>  	NULL,
>  };
>  
> @@ -368,6 +417,15 @@ static umode_t uacce_dev_is_visible(struct kobject *kobj,
>  	    (!uacce->qf_pg_num[UACCE_QFRT_DUS])))
>  		return 0;
>  
> +	if (attr == &dev_attr_isolate_strategy.attr &&
> +	    (!uacce->ops->isolate_strategy_read ||
> +	     !uacce->ops->isolate_strategy_write))

So you need either a read or write?  Why not both?

thanks,

greg k-h