From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: Re: [PATCH] pktgen: Clone skb to avoid corruption of skbs in ndo_start_xmit methods Date: Wed, 20 Jul 2011 12:36:31 -0400 Message-ID: <20110720163631.GI12349@hmsreliant.think-freely.org> References: <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> <4E270350.7050904@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 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: Ben Greear Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:55881 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751740Ab1GTQg4 (ORCPT ); Wed, 20 Jul 2011 12:36:56 -0400 Content-Disposition: inline In-Reply-To: <4E270350.7050904@candelatech.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jul 20, 2011 at 09:33:20AM -0700, Ben Greear wrote: > 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 = clone/share > >>>decision dynamically and only impacts performance for those system= s. > >>> > >> > >>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 st= art 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 *fi= le, > > 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; > > >=20 > Please only return an error if value > 1. >=20 > 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. >=20 > Thanks, > Ben >=20 Understood, thank you Ben. Neil > --=20 > Ben Greear > Candela Technologies Inc http://www.candelatech.com >=20 >=20