Re: [PATCH] pktgen: Clone skb to avoid corruption of skbs in ndo_start_xmit methods

Eric Dumazet
2011-07-20T15:30:25Z

Le mercredi 20 juillet 2011 à 11:18 -0400, Neil Horman a écrit :
> On Wed, Jul 20, 2011 at 06:24:15AM +0200, Eric Dumazet wrote:
> > Le mardi 19 juillet 2011 à 22:07 -0400, Neil Horman a écrit :
> > > >
> > > I think this is a good idea. It lets pktgen dynamically make the clone/share
> > > decision dynamically and only impacts performance for those systems.
> > >
> >
> > Just let pktgen refuse to use clone_skb command for these devices.
> >
> copy that, This is by no means final, but what do you think of this? If its
> agreeable to you, Ben, et al. I can add this to my local tree and start auditing
> all the drivers that may need to have the flag set.
>
> Regards
> Neil
>
>
> diff --git a/include/linux/if.h b/include/linux/if.h
> index 3bc63e6..ae904fe 100644
> --- a/include/linux/if.h
> +++ b/include/linux/if.h
> @@ -76,6 +76,7 @@
> #define IFF_BRIDGE_PORT 0x4000 /* device used as bridge port */
> #define IFF_OVS_DATAPATH 0x8000 /* device used as Open vSwitch
> * datapath port */
> +#define IFF_CANT_SHARE_SKB 0x10000 /* Device can't share skbs in tx path */
>
> #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..bf6d88d 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -1071,6 +1071,9 @@ static ssize_t pktgen_if_write(struct file *file,
> if (len < 0)
> return len;
>
> + if (pkt_dev->priv_flags & IFF_CANT_SHARE_SKB)
> + return -EOPNOTSUPP;
> +

Well, the general idea was to intercept the "clone_skb XXX" command and
cap XXX to 0 for said devices.

So some admin can still use pktgen without clone_skb stuff.