Re: [PATCH 1/2] net: add IFF_SKB_TX_SHARED flag to priv_flags

[Eric Dumazet <eric.dumazet@gmail.com>]

Le lundi 25 juillet 2011 à 15:45 -0400, Neil Horman a écrit :
> Pktgen attempts to transmit shared skbs to net devices, which can't be used by
> some drivers as they keep state information in skbs.  This patch adds a flag
> marking drivers as being able to handle shared skbs in their tx path.  Drivers
> are defaulted to being unable to do so, but calling ether_setup enables this
> flag, as 90% of the drivers calling ether_setup touch real hardware and can
> handle shared skbs.  A subsequent patch will audit drivers to ensure that the
> flag is set properly
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> Reported-by: Jiri Pirko <jpirko@redhat.com>
> CC: Robert Olsson <robert.olsson@its.uu.se>
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Alexey Dobriyan <adobriyan@gmail.com>
> CC: David S. Miller <davem@davemloft.net>
> ---
>  include/linux/if.h |    2 ++
>  net/core/pktgen.c  |    8 +++++---
>  net/ethernet/eth.c |    1 +
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/if.h b/include/linux/if.h
> index 3bc63e6..03489ca 100644
> --- a/include/linux/if.h
> +++ b/include/linux/if.h
> @@ -76,6 +76,8 @@
>  #define IFF_BRIDGE_PORT	0x4000		/* device used as bridge port */
>  #define IFF_OVS_DATAPATH	0x8000	/* device used as Open vSwitch
>  					 * datapath port */
> +#define IFF_TX_SKB_SHARING	0x10000	/* The interface supports sharing
> +					 * skbs on transmit */
>  
>  #define IF_GET_IFACE	0x0001		/* for querying only */
>  #define IF_GET_PROTO	0x0002
> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> index f76079c..53f3f15 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -1070,7 +1070,9 @@ static ssize_t pktgen_if_write(struct file *file,
>  		len = num_arg(&user_buffer[i], 10, &value);
>  		if (len < 0)
>  			return len;
> -
> +		if ((len > 0) &&

		if ((value > 0) ...

> +		    (!(pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)))
> +			return -ENOTSUPP;
>  		i += len;
>  		pkt_dev->clone_skb = value;
>