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 11:40:57 -0400 Message-ID: <20110720154057.GF12349@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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Ben Greear , Jiri Pirko , netdev@vger.kernel.org, Alexey Dobriyan , "David S. Miller" , robert.olsson@its.uu.se To: =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:59203 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751577Ab1GTPlP (ORCPT ); Wed, 20 Jul 2011 11:41:15 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jul 20, 2011 at 05:35:47PM +0200, Micha=C5=82 Miros=C5=82aw wro= te: > 2011/7/20 Neil Horman : > > On Wed, Jul 20, 2011 at 06:24:15AM +0200, Eric Dumazet wrote: > >> Le mardi 19 juillet 2011 =C3=A0 22:07 -0400, Neil Horman a =C3=A9c= rit : > >> > > > >> > I think this is a good idea. =C2=A0It lets pktgen dynamically ma= ke the clone/share > >> > decision dynamically and only impacts performance for those syst= ems. > >> > > >> > >> 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= ? =C2=A0If its > > agreeable to you, Ben, et al. I can add this to my local tree and s= tart 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 @@ > > =C2=A0#define IFF_BRIDGE_PORT =C2=A0 =C2=A0 =C2=A0 =C2=A00x4000 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0/* device used as bridge port */ > > =C2=A0#define IFF_OVS_DATAPATH =C2=A0 =C2=A0 =C2=A0 0x8000 =C2=A0/*= device used as Open vSwitch > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = * datapath port */ > > +#define IFF_CANT_SHARE_SKB =C2=A0 =C2=A0 0x10000 /* Device can't s= hare skbs in tx path */ > > > > =C2=A0#define IF_GET_IFACE =C2=A0 0x0001 =C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0/* for querying only */ > > =C2=A0#define IF_GET_PROTO =C2=A0 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 *f= ile, > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (len < 0) > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0return len; > > > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if (pkt_dev->pri= v_flags & IFF_CANT_SHARE_SKB) > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 return -EOPNOTSUPP; > > + > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0i +=3D len; > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0pkt_dev->clo= ne_skb =3D value; > > >=20 > I would prefer that the flag be inclusive, i.e. it should mark driver= s > which can use shared skbs. And it might be better to clone the skb in > case the flag is disabled to keep functionality working. >=20 Ok, I can agree with that. But you're ok with the general approach? Neil > Best Regards, > Micha=C5=82 Miros=C5=82aw >=20