From owner-freebsd-net@freebsd.org Wed Jul 15 23:26:38 2020 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1545E37305E for ; Wed, 15 Jul 2020 23:26:38 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gate2.funkthat.com", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4B6YRx0yj9z4dwQ for ; Wed, 15 Jul 2020 23:26:33 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.15.2/8.15.2) with ESMTPS id 06FNQPuF041954 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Wed, 15 Jul 2020 16:26:25 -0700 (PDT) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.15.2/8.15.2/Submit) id 06FNQPfw041953 for freebsd-net@FreeBSD.org; Wed, 15 Jul 2020 16:26:25 -0700 (PDT) (envelope-from jmg) Date: Wed, 15 Jul 2020 16:26:25 -0700 From: John-Mark Gurney To: freebsd-net@FreeBSD.org Subject: IF_DRV_PREPEND unlocked? Message-ID: <20200715232624.GR4213@funkthat.com> Mail-Followup-To: freebsd-net@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Operating-System: FreeBSD 11.3-STABLE amd64 X-PGP-Fingerprint: D87A 235F FB71 1F3F 55B7 ED9B D5FF 5A51 C0AC 3D65 X-Files: The truth is out there X-URL: https://www.funkthat.com/ X-Resume: https://www.funkthat.com/~jmg/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.6.1 (2016-04-27) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (gold.funkthat.com [127.0.0.1]); Wed, 15 Jul 2020 16:26:25 -0700 (PDT) X-Rspamd-Queue-Id: 4B6YRx0yj9z4dwQ X-Spamd-Bar: +++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of jmg@gold.funkthat.com has no SPF policy when checking 208.87.223.18) smtp.mailfrom=jmg@gold.funkthat.com X-Spamd-Result: default: False [3.87 / 15.00]; SUBJECT_ENDS_QUESTION(1.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-net@freebsd.org]; TO_DN_NONE(0.00)[]; AUTH_NA(1.00)[]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_SPAM_MEDIUM(0.92)[0.921]; DMARC_NA(0.00)[funkthat.com]; NEURAL_HAM_SHORT(-0.17)[-0.174]; NEURAL_SPAM_LONG(0.93)[0.926]; R_SPF_NA(0.00)[no SPF record]; FORGED_SENDER(0.30)[jmg@funkthat.com,jmg@gold.funkthat.com]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:32354, ipnet:208.87.216.0/21, country:US]; FROM_NEQ_ENVFROM(0.00)[jmg@funkthat.com,jmg@gold.funkthat.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Jul 2020 23:26:38 -0000 I happen to be looking at the implementation of IFQ_DRV_PREPEND, and unlike IFQ_DRV_DEQUEUE, it doesn't obtain the lock when manipulating the ifq. I took a brief look at a few drivers, and it looks like some of them expect that _PREPEND lock the Q like _DEQUEUE does. This is likely not an issue often, since it's an error path that likely rarely happens, but we should fix it. Should we just add the IFQ_LOCK/_UNLOCK to the macro? Comments or thoughts? -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."