From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: Re: TCP and reordering Date: Sun, 02 Dec 2012 09:31:25 +0000 Message-ID: <1354440685.21562.399.camel@shinybook.infradead.org> References: <20121127.210611.1127622873924794001.davem@davemloft.net> <1354089566.21562.20.camel@shinybook.infradead.org> <1354093703.21562.23.camel@shinybook.infradead.org> <1354100552.14302.78.camel@edumazet-glaptop> <1354103355.21562.46.camel@shinybook.infradead.org> <1354105619.14302.89.camel@edumazet-glaptop> <1354106362.21562.51.camel@shinybook.infradead.org> <1354107140.14302.140.camel@edumazet-glaptop> <1354117635.21562.63.camel@shinybook.infradead.org> <20121128161930.GB19042@kvack.org> <1354120887.21562.87.camel@shinybook.infradead.org> <1354122996.14302.427.camel@edumazet-glaptop> <1354411840.21562.373.camel@shinybook.infradead.org> <1354416005.20109.557.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="sha1"; protocol="application/x-pkcs7-signature"; boundary="=-bF8nfKIn9mZNJBu5Cbws" Cc: Benjamin LaHaise , Vijay Subramanian , David Miller , saku@ytti.fi, rick.jones2@hp.com, netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from merlin.infradead.org ([205.233.59.134]:57051 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751602Ab2LBJbi (ORCPT ); Sun, 2 Dec 2012 04:31:38 -0500 In-Reply-To: <1354416005.20109.557.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: --=-bF8nfKIn9mZNJBu5Cbws Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, 2012-12-01 at 18:40 -0800, Eric Dumazet wrote: > > +static unsigned int skb_acct_len(struct sk_buff *skb) > > +{ > > + return skb_tail_pointer(skb) - skb_network_header(skb); > > +} >=20 > Apparently this driver doesnt add any feature at alloc_netdev() time, so > it might work. (no frags in any skb) Well... as long as no driver appends stuff to the *tail* of the skb. As long as they only *prepend* headers for the device to use, we're fine. But I think that's fairly safe, for now. For PPP I think I'll end up keeping a tuple of { skb, orig_len, orig_destructor, orig_sk } for each skb which is in-flight. Since the queues of those should be *short*, and should generally complete in-order, that shouldn't be too much overhead. It'll only need a small static array of them per-channel. 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