Re: [PATCH] [BRIDGE] Set features based on slave's ones (was Ethernet Bridging: Enable Hardware Checksumming)

[Nivedita Singhvi <niv@xxxxxxxxxx>]

Catalin(ux aka Dino) BOIE wrote:

> Hello!
>
> The attached patch, makes the bridge to select features (almost all) 
> only if _all_ devices supports them.
> The patch was tested (create a bridge, add an interface, remove the 
> interface and always check features flags).
> What do you think?
While this is generally a cleaner thing to do - it breaks
what we need - Jon's  patch adds the checksum offload/SG
unconditionally precisely because we don't want it to be
an all or nothing - we'd like to utilize offload on those
devices that do support it..

thanks,
Nivedita


> ------------------------------------------------------------------------
>
> --- bridge1/net/bridge/br_private.h     2005-03-02 09:37:50.000000000 +0200
> +++ linux/net/bridge/br_private.h       2005-05-19 18:00:05.000000000 +0300
> @@ -27,6 +27,10 @@
>  #define BR_PORT_BITS   10
>  #define BR_MAX_PORTS   (1<<BR_PORT_BITS)
>  
> +#define BR_FEAT_MASK	(NETIF_F_HW_CSUM | NETIF_F_SG \
> +                       | NETIF_F_FRAGLIST | NETIF_F_IP_CSUM \
> +                       | NETIF_F_HIGHDMA | NETIF_F_TSO)
> +
>  typedef struct bridge_id bridge_id;
>  typedef struct mac_addr mac_addr;
>  typedef __u16 port_id;
> --- bridge1/net/bridge/br_device.c      2005-03-02 09:37:30.000000000 +0200
> +++ linux/net/bridge/br_device.c        2005-05-19 17:14:21.000000000 +0300
> @@ -107,4 +107,5 @@ void br_dev_setup(struct net_device *dev
>         dev->tx_queue_len = 0;
>         dev->set_mac_address = NULL;
>         dev->priv_flags = IFF_EBRIDGE;
> +       dev->features = BR_FEAT_MASK;
>  }
> --- bridge1/net/bridge/br_if.c  2005-03-02 09:38:33.000000000 +0200
> +++ linux/net/bridge/br_if.c    2005-05-19 18:21:39.000000000 +0300
> @@ -314,6 +314,27 @@ int br_min_mtu(const struct net_bridge *
>         return mtu;
>  }
>  
> +/*
> + * If slave device (@dev) doesn't support special features,
> + * turn them off globally.
> + */
> +static inline void br_features_change(struct net_bridge *br, struct net_device 
> *dev)
> +{
> +       br->dev->features &= dev->features | ~BR_FEAT_MASK;
> +}
> +
> +/*
> + * Recomputes features using slave's features
> + */
> +static void br_features_recompute(struct net_bridge *br)
> +{
> +       struct net_bridge_port *p;
> +
> +       br->dev->features |= BR_FEAT_MASK;
> +       list_for_each_entry(p, &br->port_list, list)
> +               br_features_change(br, p->dev);
> +}
> +
>  /* called with RTNL */
>  int br_add_if(struct net_bridge *br, struct net_device *dev)
>  {
> @@ -332,9 +353,10 @@ int br_add_if(struct net_bridge *br, str
>         if (IS_ERR(p = new_nbp(br, dev, br_initial_port_cost(dev))))
>                 return PTR_ERR(p);
>  
> +	br_features_change(br, dev);
> +
>         if ((err = br_fdb_insert(br, p, dev->dev_addr, 1)))
>                 destroy_nbp(p);
> - 
>  	else if ((err = br_sysfs_addif(p)))
>                 del_nbp(p);
>         else {
> @@ -368,6 +390,7 @@ int br_del_if(struct net_bridge *br, str
>  
>  	spin_lock_bh(&br->lock);
>         br_stp_recalculate_bridge_id(br);
> +       br_features_recompute(br);
>         spin_unlock_bh(&br->lock);
>  
>  	return 0;