From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [PATCH] pktgen: Clone skb to avoid corruption of skbs in ndo_start_xmit methods Date: Wed, 20 Jul 2011 09:33:20 -0700 Message-ID: <4E270350.7050904@candelatech.com> References: <1311105179-26408-1-git-send-email-nhorman@tuxdriver.com> <1311105738.3113.11.camel@edumazet-laptop> <20110719202922.GA2352@minipsycho> <1311108107.3113.22.camel@edumazet-laptop> <20110720001904.GA1992@neilslaptop.think-freely.org> <1311122593.3113.46.camel@edumazet-laptop> <4E2626E1.6030005@candelatech.com> <20110720020737.GB2692@neilslaptop.think-freely.org> <1311135855.3113.66.camel@edumazet-laptop> <20110720151827.GD12349@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Jiri Pirko , netdev@vger.kernel.org, Alexey Dobriyan , "David S. Miller" , robert.olsson@its.uu.se To: Neil Horman Return-path: Received: from mail.candelatech.com ([208.74.158.172]:45969 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317Ab1GTQdu (ORCPT ); Wed, 20 Jul 2011 12:33:50 -0400 In-Reply-To: <20110720151827.GD12349@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: On 07/20/2011 08:18 AM, Neil Horman wrote: > On Wed, Jul 20, 2011 at 06:24:15AM +0200, Eric Dumazet wrote: >> Le mardi 19 juillet 2011 =E0 22:07 -0400, Neil Horman a =E9crit : >>>> >>> I think this is a good idea. It lets pktgen dynamically make the c= lone/share >>> decision dynamically and only impacts performance for those systems= =2E >>> >> >> 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 sta= rt 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 *fil= e, > if (len< 0) > return len; > > + if (pkt_dev->priv_flags& IFF_CANT_SHARE_SKB) > + return -EOPNOTSUPP; > + > i +=3D len; > pkt_dev->clone_skb =3D value; > Please only return an error if value > 1. Also, if there is any place where user can configure pkt_dev, you would want code there to check for the CANT_SHARE_SKB flag and force clone_skb to zero if user changes to a different device that cannot share skbs. Thanks, Ben --=20 Ben Greear Candela Technologies Inc http://www.candelatech.com