Re: [PATCH 1/6] mac80211: allow no mac address until firmware load

[Dan Williams <dcbw@redhat.com>]

On Thu, 2008-07-10 at 16:57 +0200, Luis Carlos Cobo wrote:
> Originally by Johannes Berg. This patch adds support for devices that do not
> report their MAC address until the firmware is loaded. While the address is not
> known, a multicast on is used.

Johannes, thoughts on this?  Is there a better way to do it for devices
that don't know their MAC address until firmware load?

Dan

> Signed-off-by: Luis Carlos Cobo <luisca@cozybit.com>
> Tested-by: Javier Cardona <javier@cozybit.com>
> ---
>  net/mac80211/ieee80211_i.h |    1 +
>  net/mac80211/main.c        |   61 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 0 deletions(-)
> 
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index c916c2f..8e8c0eb 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -551,6 +551,7 @@ struct ieee80211_local {
>  	const struct ieee80211_ops *ops;
>  
>  	struct net_device *mdev; /* wmaster# - "master" 802.11 device */
> +	unsigned int hwid;
>  	int open_count;
>  	int monitors, cooked_mntrs;
>  	/* number of interfaces with corresponding FIF_ flags */
> diff --git a/net/mac80211/main.c b/net/mac80211/main.c
> index cf477ad..2204aa5 100644
> --- a/net/mac80211/main.c
> +++ b/net/mac80211/main.c
> @@ -178,6 +178,20 @@ static inline int identical_mac_addr_allowed(int type1, int type2)
>  		  type2 == IEEE80211_IF_TYPE_VLAN)));
>  }
>  
> +static void calculate_invalid_mac(u8 *addr, unsigned int hwid)
> +{
> +	/*
> +	 * Random multicast, private use address with hwid mixed in.
> +	 * Must be multicast to let is_valid_ether_addr() fail on it.
> +	 */
> +	addr[0] = 0xe7;
> +	addr[1] = 0xc4;
> +	addr[2] = 0x2e ^ ((hwid >> 24) & 0xFF);
> +	addr[3] = 0xdd ^ ((hwid >> 16) & 0xFF);
> +	addr[4] = 0xcb ^ ((hwid >>  8) & 0xFF);
> +	addr[5] = 0x8c ^ ((hwid >>  0) & 0xFF);
> +}
> +
>  static int ieee80211_open(struct net_device *dev)
>  {
>  	struct ieee80211_sub_if_data *sdata, *nsdata;
> @@ -187,9 +201,17 @@ static int ieee80211_open(struct net_device *dev)
>  	u32 changed = 0;
>  	int res;
>  	bool need_hw_reconfig = 0;
> +	u8 inval_addr[ETH_ALEN];
>  
>  	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
>  
> +	calculate_invalid_mac(inval_addr, local->hwid);
> +
> +	/* fail early if user set an invalid address */
> +	if (compare_ether_addr(dev->dev_addr, inval_addr) &&
> +	    !is_valid_ether_addr(dev->dev_addr))
> +		return -EADDRNOTAVAIL;
> +
>  	/* we hold the RTNL here so can safely walk the list */
>  	list_for_each_entry(nsdata, &local->interfaces, list) {
>  		struct net_device *ndev = nsdata->dev;
> @@ -288,6 +310,32 @@ static int ieee80211_open(struct net_device *dev)
>  		ieee80211_led_radio(local, local->hw.conf.radio_enabled);
>  	}
>  
> +	/*
> +	 * Check all interfaces and copy the hopefully now-present
> +	 * MAC address to those that have the special invalid one.
> +	 */
> +	list_for_each_entry(nsdata, &local->interfaces, list) {
> +		struct net_device *ndev = nsdata->dev;
> +
> +		/*
> +		 * No need to check netif_running since we do not allow
> +		 * it to start up with this invalid address.
> +		 */
> +		if (compare_ether_addr(inval_addr, ndev->dev_addr) == 0)
> +			memcpy(ndev->dev_addr,
> +			       local->hw.wiphy->perm_addr,
> +			       ETH_ALEN);
> +	}
> +
> +	/*
> +	 * Validate the MAC address for this device.
> +	 */
> +	if (!is_valid_ether_addr(dev->dev_addr)) {
> +		if (!local->open_count && local->ops->stop)
> +			local->ops->stop(local_to_hw(local));
> +		return -EADDRNOTAVAIL;
> +	}
> +
>  	switch (sdata->vif.type) {
>  	case IEEE80211_IF_TYPE_VLAN:
>  		list_add(&sdata->u.vlan.list, &sdata->u.vlan.ap->u.ap.vlans);
> @@ -995,6 +1043,8 @@ void ieee80211_if_setup(struct net_device *dev)
>  	dev->open = ieee80211_open;
>  	dev->stop = ieee80211_stop;
>  	dev->destructor = ieee80211_if_free;
> +	/* we will validate the address ourselves in ->open */
> +	dev->validate_addr = NULL;
>  }
>  
>  /* everything else */
> @@ -1571,6 +1621,8 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
>  	struct ieee80211_local *local;
>  	int priv_size;
>  	struct wiphy *wiphy;
> +	static atomic_t hw_counter = ATOMIC_INIT(0);
> +	u8 inval_addr[ETH_ALEN];
>  
>  	/* Ensure 32-byte alignment of our private data and hw private data.
>  	 * We use the wiphy priv data for both our ieee80211_local and for
> @@ -1601,6 +1653,15 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
>  	local = wiphy_priv(wiphy);
>  	local->hw.wiphy = wiphy;
>  
> +	/*
> +	 * Hack for devices that cannot read the mac address until they are
> +	 * started... keep an invalid multicast address as the device MAC...
> +	 * Read on in ieee80211_open().
> +	 */
> +	local->hwid = atomic_inc_return(&hw_counter);
> +	calculate_invalid_mac(inval_addr, local->hwid);
> +	memcpy(local->hw.wiphy->perm_addr, inval_addr, ETH_ALEN);
> +
>  	local->hw.priv = (char *)local +
>  			 ((sizeof(struct ieee80211_local) +
>  			   NETDEV_ALIGN_CONST) & ~NETDEV_ALIGN_CONST);