Subject: [PATCH 1/5] VFIO: platform: add reset_list and register/unregister functions

From: [email-masked] (Alex Williamson)
Date: Wed, 13 May 2015 12:32:05 -0600

On Thu, 2015-05-07 at 16:27 +0200, Eric Auger wrote:
> vfio_platform_common now stores a lists of available reset functions.
> Two functions are exposed to register/unregister a reset function. A
> reset function is paired with a compat string.
> 
> Signed-off-by: Eric Auger <[email-masked]>
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 63 +++++++++++++++++++++++++++
>  drivers/vfio/platform/vfio_platform_private.h | 13 ++++++
>  2 files changed, 76 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index abcff7a..edbf24c 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -23,6 +23,9 @@
>  
>  #include "vfio_platform_private.h"
>  
> +struct list_head reset_list;
> +LIST_HEAD(reset_list);
> +

Redundant?  Static?

>  static DEFINE_MUTEX(driver_lock);
>  
>  static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> @@ -511,6 +514,13 @@ EXPORT_SYMBOL_GPL(vfio_platform_probe_common);
>  struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
>  {
>  	struct vfio_platform_device *vdev;
> +	struct vfio_platform_reset_node *iter, *tmp;
> +
> +	list_for_each_entry_safe(iter, tmp, &reset_list, link) {
> +		list_del(&iter->link);
> +		kfree(iter->compat);
> +		kfree(iter);
> +	}

This doesn't make sense.  We allow reset functions to be registered and
unregistered, but we forget them all when any device is released?!

>  
>  	vdev = vfio_del_group_dev(dev);
>  	if (vdev)
> @@ -519,3 +529,56 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
>  	return vdev;
>  }
>  EXPORT_SYMBOL_GPL(vfio_platform_remove_common);
> +
> +int vfio_platform_register_reset(char *compat, struct module *reset_owner,
> +				 vfio_platform_reset_fn_t reset)
> +{
> +	struct vfio_platform_reset_node *node, *iter;
> +	bool found = false;
> +
> +	list_for_each_entry(iter, &reset_list, link) {
> +		if (!strcmp(iter->compat, compat)) {
> +			found = true;

Just return errno here

> +			break;
> +		}
> +	}
> +	if (found)
> +		return -EINVAL;
> +
> +	node = kmalloc(sizeof(*node), GFP_KERNEL);
> +	if (!node)
> +		return -ENOMEM;
> +
> +	node->compat = kstrdup(compat, GFP_KERNEL);
> +	if (!node->compat)

Leaking node

> +		return -ENOMEM;
> +
> +	node->owner = reset_owner;
> +	node->reset = reset;
> +
> +	list_add(&node->link, &reset_list);

Isn't this racy?  Don't we need some locks around the list?

> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vfio_platform_register_reset);
> +
> +int vfio_platform_unregister_reset(char *compat)
> +{
> +	struct vfio_platform_reset_node *iter;
> +	bool found = false;
> +
> +	list_for_each_entry(iter, &reset_list, link) {
> +		if (!strcmp(iter->compat, compat)) {

Return errno here

> +			found = true;
> +			break;
> +		}
> +	}
> +	if (!found)
> +		return -EINVAL;
> +
> +	list_del(&iter->link);

Racy

> +	kfree(iter->compat);
> +	kfree(iter);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vfio_platform_unregister_reset);
> +
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 5d31e04..da2d60b 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -69,6 +69,15 @@ struct vfio_platform_device {
>  	int	(*get_irq)(struct vfio_platform_device *vdev, int i);
>  };
>  
> +typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);

Seems like this ought to be in a non-private header if we're exporting
the [un]register functions.
> +
> +struct vfio_platform_reset_node {
> +	struct list_head link;
> +	char *compat;
> +	struct module *owner;
> +	vfio_platform_reset_fn_t reset;
> +};
> +
>  extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  				      struct device *dev);
>  extern struct vfio_platform_device *vfio_platform_remove_common
> @@ -82,4 +91,8 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  					unsigned start, unsigned count,
>  					void *data);
>  
> +extern int vfio_platform_register_reset(char *compat, struct module *owner,
> +					vfio_platform_reset_fn_t reset);
> +extern int vfio_platform_unregister_reset(char *compat);
> +
>  #endif /* VFIO_PLATFORM_PRIVATE_H */