Re: [PATCHv3 bluetooth-next 2/4] nl802154: add set interface cmd

[Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>]

On Tue,  7 Apr 2015 13:49:51 +0200
Alexander Aring <alex.aring@gmail.com> wrote:

> This patch introduce the NL802154_CMD_SET_INTERFACE command which
> handles setting of all wpan interface mac attributes. his will
> introduce an easilier wpan mac settings handling in userspace
> application with nl802154.
> 
> Signed-off-by: Alexander Aring <alex.aring@gmail.com>
> ---
>  net/ieee802154/nl802154.c | 110
> ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 110
> insertions(+)
> 
> diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
> index c12c07f..e2f50ba 100644
> --- a/net/ieee802154/nl802154.c
> +++ b/net/ieee802154/nl802154.c
> @@ -603,6 +603,108 @@ static int nl802154_get_interface(struct
> sk_buff *skb, struct genl_info *info) return genlmsg_reply(msg, info);
>  }
>  
> +static int nl802154_set_interface(struct sk_buff *skb, struct
> genl_info *info) +{
> +	struct cfg802154_registered_device *rdev = info->user_ptr[0];
> +	struct net_device *dev = info->user_ptr[1];
> +	struct wpan_dev *wpan_dev = dev->ieee802154_ptr;
> +	int ret;
> +
> +	if (info->attrs[NL802154_ATTR_PAN_ID]) {
> +		__le16 pan_id;
> +
> +		if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
> +			return -EINVAL;
> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		pan_id =
> nla_get_le16(info->attrs[NL802154_ATTR_PAN_ID]);
> +		ret = rdev_set_pan_id(rdev, wpan_dev, pan_id);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (info->attrs[NL802154_ATTR_SHORT_ADDR]) {
> +		__le16 short_addr;
> +
> +		if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
> +			return -EINVAL;

This is not good. You may have partially applied the requested settings
when you return with an error, leaving the device in some intermediate
state that is most likely not useful. It'd be better to first check
whether all settings can be applied, and then apply them all at once.
But even then we have a problem with rolling back some changes if a
command fails :/

> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		short_addr =
> nla_get_le16(info->attrs[NL802154_ATTR_SHORT_ADDR]); +
> +		ret = rdev_set_short_addr(rdev, wpan_dev,
> short_addr);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (info->attrs[NL802154_ATTR_MAX_FRAME_RETRIES]) {
> +		s8 max_frame_retries;
> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		max_frame_retries = nla_get_s8(
> +
> info->attrs[NL802154_ATTR_MAX_FRAME_RETRIES]);
> +		if (max_frame_retries < -1 || max_frame_retries > 7)
> +			return -EINVAL;
> +
> +		ret = rdev_set_max_frame_retries(rdev, wpan_dev,
> +						 max_frame_retries);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (info->attrs[NL802154_ATTR_MIN_BE] &&
> +	    info->attrs[NL802154_ATTR_MAX_BE]) {
> +		u8 min_be, max_be;
> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		min_be =
> nla_get_u8(info->attrs[NL802154_ATTR_MIN_BE]);
> +		max_be =
> nla_get_u8(info->attrs[NL802154_ATTR_MAX_BE]);
> +		if (max_be < 3 || max_be > 8 || min_be > max_be)
> +			return -EINVAL;
> +
> +		ret = rdev_set_backoff_exponent(rdev, wpan_dev,
> min_be, max_be);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (info->attrs[NL802154_ATTR_MAX_CSMA_BACKOFFS]) {
> +		u8 max_csma_backoffs;
> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		max_csma_backoffs = nla_get_u8(
> +
> info->attrs[NL802154_ATTR_MAX_CSMA_BACKOFFS]);
> +		if (max_csma_backoffs > 5)
> +			return -EINVAL;
> +
> +		ret = rdev_set_max_csma_backoffs(rdev, wpan_dev,
> +						 max_csma_backoffs);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (info->attrs[NL802154_ATTR_LBT_MODE]) {
> +		bool mode;
> +
> +		if (netif_running(dev))
> +			return -EBUSY;
> +
> +		mode
> = !!nla_get_u8(info->attrs[NL802154_ATTR_LBT_MODE]);
> +		return rdev_set_lbt_mode(rdev, wpan_dev, mode);
> +	}
> +
> +	return 0;
> +}
> +
>  static int nl802154_new_interface(struct sk_buff *skb, struct
> genl_info *info) {
>  	struct cfg802154_registered_device *rdev = info->user_ptr[0];
> @@ -964,6 +1066,14 @@ static const struct genl_ops nl802154_ops[] = {
>  				  NL802154_FLAG_NEED_RTNL,
>  	},
>  	{
> +		.cmd = NL802154_CMD_SET_INTERFACE,
> +		.doit = nl802154_set_interface,
> +		.policy = nl802154_policy,
> +		.flags = GENL_ADMIN_PERM,
> +		.internal_flags = NL802154_FLAG_NEED_NETDEV |
> +				  NL802154_FLAG_NEED_RTNL,
> +	},
> +	{
>  		.cmd = NL802154_CMD_DEL_INTERFACE,
>  		.doit = nl802154_del_interface,
>  		.policy = nl802154_policy,