Re: [PATCH 1/4] vfio: platform: add capability to register a reset function

[Alex Williamson <alex.williamson@redhat.com>]

On Sun, 2015-10-18 at 18:00 +0200, Eric Auger wrote:
> In preparation for subsequent changes in reset function lookup,
> lets introduce a dynamic list of reset combos (compat string,
> reset module, reset function). The list can be populated/voided with
> two new functions, vfio_platform_register/unregister_reset. Those are
> not yet used in this patch.
> 
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 55 +++++++++++++++++++++++++++
>  drivers/vfio/platform/vfio_platform_private.h | 14 +++++++
>  2 files changed, 69 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index e43efb5..d36afc9 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -23,6 +23,8 @@
>  
>  #include "vfio_platform_private.h"
>  
> +struct list_head reset_list;

What's the purpose of this one above?

> +LIST_HEAD(reset_list);

static

I think you also need a mutex protecting this list, otherwise nothing
prevents concurrent list changes and walks.  A rw lock probably fits the
usage model best, but I don't expect much contention if you just want to
use a mutex.

>  static DEFINE_MUTEX(driver_lock);
>  
>  static const struct vfio_platform_reset_combo reset_lookup_table[] = {
> @@ -573,3 +575,56 @@ 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(struct module *reset_owner, char *compat,

const char *

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

Leaks node

> +
> +	node->owner = reset_owner;
> +	node->reset = reset;
> +
> +	list_add(&node->link, &reset_list);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vfio_platform_register_reset);
> +
> +int vfio_platform_unregister_reset(char *compat)

const char *

> +{
> +	struct vfio_platform_reset_node *iter;
> +	bool found = false;
> +
> +	list_for_each_entry(iter, &reset_list, link) {
> +		if (!strcmp(iter->compat, compat)) {
> +			found = true;
> +			break;
> +		}
> +	}
> +	if (!found)
> +		return -EINVAL;
> +
> +	list_del(&iter->link);
> +	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 1c9b3d5..17323f0 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -76,6 +76,15 @@ struct vfio_platform_reset_combo {
>  	const char *module_name;
>  };
>  
> +typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
> +
> +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
> @@ -89,4 +98,9 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  					unsigned start, unsigned count,
>  					void *data);
>  
> +extern int vfio_platform_register_reset(struct module *owner,
> +					char *compat,
> +					vfio_platform_reset_fn_t reset);
> +extern int vfio_platform_unregister_reset(char *compat);
> +
>  #endif /* VFIO_PLATFORM_PRIVATE_H */