Re: [B.A.T.M.A.N.] [PATCH] batman-adv: change VID semantic in the BLA code

[Antonio Quartulli <ordex@autistici.org>]

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On Wed, Apr 03, 2013 at 11:17:14AM +0200, Antonio Quartulli wrote:
> From: Antonio Quartulli <antonio@open-mesh.com>
> 
> In order to make batman-adv fully vlan aware later, the
> semantic used for variables storing the VLAN ID values has
> to be changed in order to be adapted to the new one which
> will be used batman-adv wide.
> 
> In particular, the VID has to be an "_unsigned_ short int"
> and its 4 MSB will be used as a flag bitfield, while the
> remaining 12 bits are used to store the real VID value
> 
> Cc: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
> Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>

[cut..]

> diff --git a/packet.h b/packet.h
> index a51ccfc..d5464f6 100644
> --- a/packet.h
> +++ b/packet.h
> @@ -105,6 +105,14 @@ enum batadv_tt_client_flags {
>  	BATADV_TT_CLIENT_PENDING = BIT(10),
>  };
>  
> +/**
> + * batadv_vlan_flags - flags for the four MSB of any vlan ID field
> + * @BATADV_VLAN_HAS_TAG: whether the field contains a valid vlan tag or not
> + */
> +enum batadv_vlan_flags {
> +	BATADV_VLAN_HAS_TAG	= BIT(15),
> +};
> +
>  /* claim frame types for the bridge loop avoidance */
>  enum batadv_bla_claimframe {
>  	BATADV_CLAIM_TYPE_CLAIM		= 0x00,
> diff --git a/soft-interface.c b/soft-interface.c
> index 403b8c4..34597a2 100644
> --- a/soft-interface.c
> +++ b/soft-interface.c
> @@ -154,7 +154,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
>  						    0x00, 0x00};
>  	unsigned int header_len = 0;
>  	int data_len = skb->len, ret;
> -	short vid __maybe_unused = -1;
> +	unsigned short vid __maybe_unused = BATADV_NO_FLAGS;
>  	bool do_bcast = false;
>  	uint32_t seqno;
>  	unsigned long brd_delay = 1;
> @@ -303,7 +303,7 @@ void batadv_interface_rx(struct net_device *soft_iface,
>  	struct ethhdr *ethhdr;
>  	struct vlan_ethhdr *vhdr;
>  	struct batadv_header *batadv_header = (struct batadv_header *)skb->data;
> -	short vid __maybe_unused = -1;
> +	unsigned short vid __maybe_unused = BATADV_NO_FLAGS;
>  	__be16 ethertype = __constant_htons(ETH_P_BATMAN);
>  	bool is_bcast;

I just realised that this change is going to break compatibility because we
change the menaing of the value that BLA sends over the wire.

We must postpone this change to the next (BIG) compat bump.

Cheers,

-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

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