Return-path: Received: from xc.sipsolutions.net ([83.246.72.84]:55291 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752772AbYKSM3g (ORCPT ); Wed, 19 Nov 2008 07:29:36 -0500 Subject: Re: [PATCH/RFT] iwlagn: fix RX skb alignment From: Johannes Berg To: Tomas Winkler Cc: John Linville , reinette chatre , Marcel Holtmann , "Luis R. Rodriguez" , Zhu Yi , linux-wireless In-Reply-To: <1ba2fa240811190424v4b9074e5u4e679bea278b1f3@mail.gmail.com> (sfid-20081119_132502_191402_DA089F51) References: <1226969241.4014.24.camel@johannes.berg> <1227001390.4014.43.camel@johannes.berg> <1ba2fa240811180613g48c94199s67e4334e89282e76@mail.gmail.com> <1227055693.4014.95.camel@johannes.berg> <1ba2fa240811190121h3ff51824o90b72a206192e793@mail.gmail.com> <1227094832.26243.10.camel@johannes.berg> <1ba2fa240811190424v4b9074e5u4e679bea278b1f3@mail.gmail.com> (sfid-20081119_132502_191402_DA089F51) Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-2ARwvjIcdMNmH8m/NHzF" Date: Wed, 19 Nov 2008 13:28:57 +0100 Message-Id: <1227097737.26243.28.camel@johannes.berg> (sfid-20081119_132939_630525_7FD5CF77) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: --=-2ARwvjIcdMNmH8m/NHzF Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2008-11-19 at 14:24 +0200, Tomas Winkler wrote: > On Wed, Nov 19, 2008 at 1:40 PM, Johannes Berg > wrote: > > On Wed, 2008-11-19 at 11:21 +0200, Tomas Winkler wrote: > > > >> > Indeed. One would seem to be the buffer list itself, which also need= s to > >> > fit within a 40-bit mask with 256 alignment (rxq->bd), the rb_stts n= eeds > >> > 16-byte alignment which probably is always satisfied, but I'm not su= re, > >> > you'll need to research the alignment guarantees. > >> > >> Note these are allocated using persistent calls and not kmalloc I hope > >> at least does are page alignment. > > > > Good point. On powerpc at least that uses alloc_pages internally. >=20 > Not sure if if wouldn't be better just work directly with pages in RX? Well, in theory yes, but it's not possible to have skb->data point to a separate page rather than a kmalloc area. And while you could allocate an skb with very little headroom and the rest of the skb data in the fraglist with pages, mac80211 couldn't handle it. johannes --=-2ARwvjIcdMNmH8m/NHzF Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iQIcBAABAgAGBQJJJAaFAAoJEKVg1VMiehFY53oP/3xyJxL9BXbnRQry9bzPB7JL 73f0V8AAHxU1Oo5Nd/Bqin7IKIJ4xsNhbNSoYdC0McDsJPGG2uqPWtjJJRMutSU2 8ILI2U8RQThhUWz8Ta2aMAX46IfdQ1JfTFTk2COAIC6RygOSFU3x09olALX4DWx9 4ehjA+v3QdxV6NgnSuoaeE0NSRVKZBgpCsO7fyxV0ABXYjYovXd2ak6/guvIRrdz Kl7nnhLGMOdcQjY4/Ts0xgJzQl21DvXGv/jHADW0gzO0FMfgmsrieKp6Csovlu+z HHxS0oK3v0hHep2tCw4W6jViPx+MggQ63U5nSsta60e9hzhHgMkoLLgp9QG1RITX sKKWYhj8Tdd0jrLzFof6JUM8K3kSTR0ZEoj8bBhnuu48ZXUBjPcrlil57x5X0d8u F60hHDqVzzXm5piaiP8A0Z5jwiN7/8AfWjGBZx1BnCWztcsIqMDZTHsHmk5Umbb/ z5em/qCWkcEKPaRR5Lx8qjwkMBXvsEdaoazAJ7535Y9YcHMAk6qjopM/CvjjKU4b YmOBKHG95fTes14BjCcw9E76iEYQQKfh4tNHaf7LaoRNwShPGrytMTZo3iOMofaX YyWufE2P9aOC75wSacDhCbZ7I3FO1gmfXwRIopwa1EPTwxGRy2AAitsyxBu2YkJB DxSGEv+XPv3yZV3dYvxF =P4Et -----END PGP SIGNATURE----- --=-2ARwvjIcdMNmH8m/NHzF--