From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16BFCECDFBB for ; Fri, 20 Jul 2018 06:24:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDE2220673 for ; Fri, 20 Jul 2018 06:24:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BDE2220673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727822AbeGTHLF (ORCPT ); Fri, 20 Jul 2018 03:11:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:58998 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727289AbeGTHLF (ORCPT ); Fri, 20 Jul 2018 03:11:05 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id DD1F2AD9F; Fri, 20 Jul 2018 06:24:25 +0000 (UTC) From: NeilBrown To: Herbert Xu Date: Fri, 20 Jul 2018 16:24:16 +1000 Cc: David Miller , tgraf@suug.ch, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH - revised] rhashtable: detect when object movement might have invalidated a lookup In-Reply-To: <20180717063020.rpqsgrbpwavklxz7@gondor.apana.org.au> References: <20180601160613.7ud25g2ux55k3bma@gondor.apana.org.au> <87k1q8yh70.fsf@notabene.neil.brown.name> <20180711.224658.2077863065492745521.davem@davemloft.net> <20180711.224801.1129067473269289703.davem@davemloft.net> <87fu0kt5m0.fsf@notabene.neil.brown.name> <20180716005134.q4rfkfn3m5zzwt62@gondor.apana.org.au> <874lh0t1ls.fsf@notabene.neil.brown.name> <20180716021653.xtbyetdfc2uzxub3@gondor.apana.org.au> <871sc3uah9.fsf@notabene.neil.brown.name> <20180717063020.rpqsgrbpwavklxz7@gondor.apana.org.au> Message-ID: <87y3e6qvan.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, Jul 17 2018, Herbert Xu wrote: > On Mon, Jul 16, 2018 at 01:26:42PM +1000, NeilBrown wrote: >> >> Look in Documenation/RCU/rculist_nulls.txt. >> The very first example is a typical lookup for a nulls list. >> The above sample code would read: > > OK, but how will this work with rhlist? It would be very bad to > have a feature that works for rhashtable but fails in strange > ways when you use rhlist. It should be easy enough to handle in rhlist too. When inserting a new object, we put it at the start of the chain, and if there was already a list with the same key, it gets moved to the new object. A walk could see some objects repeatedly when this happens, but that is already possible. Thanks, NeilBrown > > Cheers, > --=20 > Email: Herbert Xu > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAltRgBAACgkQOeye3VZi gbmD4Q/6A17Rg4xFwye/fH2dwE/5rCQu0XOZF3q9MZyezggXgnTkreqh+lkR3pdt FtYHnDCps9vCrVeGwbnFun6TD4Q5iMnstdRddsaq1xCQykvbg+obRqU0N3bbzcJ6 JRsmg9TaxAv4OYX3LTrUhcdLEKLs4Hq/t0D64SFlBsHUR/GiYPGVioPZ8f+SmwV8 xBC8ulaGXh901f7NUT/KklHi8MAEa2nCSIJxng1dCaayjOZaXcgf3mEAc3gu4TV+ m4QrgnXAnhn3+yknKxNBildy1/ZIBYWpR283vrW1XDkmr63lbN0VstlRLM+VaTV5 yGexu+Riy3+J1/utX+Ruz+iq4WCiZBjoGtHIapBiHNXaZsWZlNS/2rPRdtNDOHjm iCk/xWt/1Avp0Y07mV4ikqtWdQtvMyGCDi+CDJX09KJLxLJlBJeJDMnXz2odiFCN fThGKNyD2zKJA8GGNumlR9YKr0e+DjuTS7RS0coI3U9W4tgCxLWSVZvs4H8FokSL oB+gd/SpqUgcmjp1DzRBWIdz5Vg6JkPE6dNjCQKx+h6XqBITwLHKbEGW8OJhW3CG WnWZH08NfjgV1oVSG+5EWlVvGiqwEyNQJNABW+sFmF72QAUNr5epu4pIedkhszpC SYWiUTvLHSYxdr9QnsieZLdX0c8399JS0ojFOEQ5cX/7+Fwm3r4= =6aZF -----END PGP SIGNATURE----- --=-=-=--