From owner-freebsd-arch@freebsd.org Wed Oct 5 13:14:22 2016 Return-Path: Delivered-To: freebsd-arch@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B607AAF5288 for ; Wed, 5 Oct 2016 13:14:22 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 33213753; Wed, 5 Oct 2016 13:14:22 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id u95DEDcQ088059 (version=TLSv1 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Wed, 5 Oct 2016 16:14:13 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua u95DEDcQ088059 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id u95DECEG088057; Wed, 5 Oct 2016 16:14:12 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Wed, 5 Oct 2016 16:14:12 +0300 From: Konstantin Belousov To: Lewis Donzis Cc: Jilles Tjoelker , deischen@freebsd.org, freebsd-arch@freebsd.org Subject: Re: mq on kqueue broken after upgrade to FreeBSD 11 Message-ID: <20161005131412.GF38409@kib.kiev.ua> References: <20160930184418.1047afc2@kan> <20161001092515.GW38409@kib.kiev.ua> <20161001201655.GA91457@stack.nl> <20161001210722.GC38409@kib.kiev.ua> <20161001231524.GB91457@stack.nl> <20161002114613.GE38409@kib.kiev.ua> <20161002132242.GA2628@stack.nl> <7A72D37B-6C57-41FE-893F-592235A19D9D@perftech.com> <20161002163708.GG38409@kib.kiev.ua> <95CA96C0-A0F2-46B6-8BEA-E1A923FEC91D@perftech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <95CA96C0-A0F2-46B6-8BEA-E1A923FEC91D@perftech.com> User-Agent: Mutt/1.6.1 (2016-04-27) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Oct 2016 13:14:22 -0000 On Mon, Oct 03, 2016 at 07:27:54AM -0500, Lewis Donzis wrote: > That's a very good point, I hadn't considered those other functions, > and it???s clear that an fd is allocated and stored in the mqd_t. > But using close() instead of mq_close() wouldn't delete the sigevent > or free the memory that was allocated by mq_open(). In other words, > I don't understand why you'd ever want/need to use close() on the > underlying fd. I really have troubles giving any useful interpretation to your question. OS provides the kernel service which backs the posix message queue implementation in userspace, as a file descriptor. To release resources designated by the file descriptor, it must be closed, as in, close(2) must be called. Librt does this in mq_close(3). Why should I need to show a case of using close(2) on kernel mq descriptor (perhaps besides librt) ? And how this changes or augments the fact that kmq is file descriptor ?