From owner-freebsd-net@FreeBSD.ORG Thu Feb 5 16:37:53 2015 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 1BD55F84 for ; Thu, 5 Feb 2015 16:37:53 +0000 (UTC) Received: from phabric-backend.isc.freebsd.org (phabric-backend.isc.freebsd.org [IPv6:2001:4f8:3:ffe0:406a:0:50:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id CFBA06B4 for ; Thu, 5 Feb 2015 16:37:52 +0000 (UTC) Received: from phabric-backend.isc.freebsd.org (phabric-backend.isc.freebsd.org [127.0.1.5]) by phabric-backend.isc.freebsd.org (8.14.9/8.14.9) with ESMTP id t15Gbq1v030693 for ; Thu, 5 Feb 2015 16:37:52 GMT (envelope-from root@phabric-backend.isc.freebsd.org) Received: (from root@localhost) by phabric-backend.isc.freebsd.org (8.14.9/8.14.9/Submit) id t15GbqiI030692; Thu, 5 Feb 2015 16:37:52 GMT (envelope-from root) Date: Thu, 5 Feb 2015 16:37:52 +0000 To: freebsd-net@freebsd.org From: "rrs (Randall Stewart)" Subject: [Differential] [Commented On] D1777: Associated fix for arp/nd6 timer usage. Message-ID: X-Priority: 3 Thread-Topic: D1777: Associated fix for arp/nd6 timer usage. X-Herald-Rules: none X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-Cc: X-Phabricator-Cc: X-Phabricator-Cc: X-Phabricator-Cc: X-Phabricator-Cc: X-Phabricator-Cc: In-Reply-To: References: Thread-Index: N2Y2Y2VmY2ZjNTc1MTM4NTA3YmIzZDk3NmE4IFTTnGA= X-Phabricator-Sent-This-Message: Yes X-Mail-Transport-Agent: MetaMTA X-Auto-Response-Suppress: All X-Phabricator-Mail-Tags: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Feb 2015 16:37:53 -0000 rrs added a comment. Adrian: I know he said callout_drain, but just like in TCP that is *not* always possible. In the case of the arp/nd6 code lock are held (same as TCP) so you can't do a callout_drain. Thats why the original author put ref-counting in with the idea that the timer would kill it if it had to execute.. they just did not anticipate that by having the callout grab the lock, it would then be making references to it after they deleted it in this one case. Maybe I need to go back through the code and using jhb's a-n outline point out the lines of code so everyone can follow along how this fixes it... REVISION DETAIL https://reviews.freebsd.org/D1777 To: rrs, imp, sbruno, gnn, rwatson, lstewart, kostikbel, adrian, bz, jhb Cc: bz, emaste, hiren, julian, hselasky, freebsd-net