From owner-freebsd-net@FreeBSD.ORG Wed Feb 4 14:03:23 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 6A87B3DE for ; Wed, 4 Feb 2015 14:03:23 +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 24FFDB11 for ; Wed, 4 Feb 2015 14:03:23 +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 t14E3MF0052898 for ; Wed, 4 Feb 2015 14:03:22 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 t14E3M4t052897; Wed, 4 Feb 2015 14:03:22 GMT (envelope-from root) Date: Wed, 4 Feb 2015 14:03:22 +0000 To: freebsd-net@freebsd.org From: "julian (JulianElischer)" Subject: [Differential] [Commented On] D1711: Changes to the callout code to restore active semantics and also add a test-framework and test to validate thecallout code (and potentially for use by other tests). Message-ID: <57443999a8bd0b310f9bea2e2412360d@localhost.localdomain> X-Priority: 3 Thread-Topic: D1711: Changes to the callout code to restore active semantics and also add a test-framework and test to validate the callout code (and potentially for use by other tests). 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: X-Phabricator-Cc: X-Phabricator-Cc: X-Phabricator-Cc: In-Reply-To: References: Thread-Index: Y2JjMTcyODJkYzgxM2NkZDFjY2RhOGRmMTlkIFTSJqo= 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: Wed, 04 Feb 2015 14:03:23 -0000 julian added a comment. let me see if this is correct.. I'm assuming that the reference count can not change if you hold the lock? if so then before releasing the lock, we can check if the count is 1.. if it is then we are the only person who even knows where this thing is so there can't be any new references added.. having stopped the callout action from happening we inherit it's reference. If it IS 1 then we can drop the lock because no one else can get it, and we can then drop the reference safely. the question is what to do if it is NOT 1? can that happen? who else might hold a reference..? we drop the lock, and wait a moment, and then retake the lock and retry? if it can not be > 1 then maybe an assert to that affect may be a safe thing to add. REVISION DETAIL https://reviews.freebsd.org/D1711 To: rrs, gnn, rwatson, lstewart, jhb, kostikbel, hselasky, adrian, imp, sbruno Cc: julian, hiren, jhb, kostikbel, emaste, delphij, neel, erj, freebsd-net