From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1Y4XOZ-0002vO-DD for mharc-qemu-trivial@gnu.org; Fri, 26 Dec 2014 11:05:43 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58019) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y4RwV-0007bH-A7 for qemu-trivial@nongnu.org; Fri, 26 Dec 2014 05:16:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y4RwU-0002MP-FD for qemu-trivial@nongnu.org; Fri, 26 Dec 2014 05:16:23 -0500 Received: from relay.parallels.com ([195.214.232.42]:44017) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y4RwQ-0002KS-5T; Fri, 26 Dec 2014 05:16:18 -0500 Received: from [10.30.3.11] (helo=mail.sw.ru) by relay.parallels.com with esmtps (TLSv1:AES128-SHA:128) (Exim 4.84) (envelope-from ) id 1Y4RwI-0003jY-Qp; Fri, 26 Dec 2014 13:16:10 +0300 Received: from irbis.local (10.30.2.139) by mail.sw.ru (10.30.3.11) with Microsoft SMTP Server (TLS) id 14.3.210.2; Fri, 26 Dec 2014 13:16:10 +0300 Message-ID: <549D356A.4050506@parallels.com> Date: Fri, 26 Dec 2014 13:16:10 +0300 From: "Denis V. Lunev" User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Peter Maydell , Tiejun Chen References: <1419581126-12927-1-git-send-email-tiejun.chen@intel.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.30.2.139] X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 195.214.232.42 X-Mailman-Approved-At: Fri, 26 Dec 2014 11:05:41 -0500 Cc: QEMU Trivial , Paolo Bonzini , QEMU Developers , kvm-devel Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] kvm_irqchip_assign_irqfd: just set irqfd in case of kvm_irqfds_enabled() X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Dec 2014 10:16:24 -0000 On 26/12/14 13:00, Peter Maydell wrote: > On 26 December 2014 at 08:05, Tiejun Chen wrote: >> We should avoid to set irqfd{} unconditionally. >> >> Signed-off-by: Tiejun Chen > > Is there a hot path that we use this on such that the difference > in code order matters at all? > > thanks > -- PMM > IMHO the patch does not change anything even on hot-hot path. the declaration 'struct kvm_irqfd irqfd = {};' will result in memset inside. Thus in order to achieve declared goal author should declare struct kvm_irqfd irqfd; and perform memset(&irqfd, 0, sizeof(irqfd)); later after the check. Regards, Den From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Denis V. Lunev" Subject: Re: [PATCH] kvm_irqchip_assign_irqfd: just set irqfd in case of kvm_irqfds_enabled() Date: Fri, 26 Dec 2014 13:16:10 +0300 Message-ID: <549D356A.4050506@parallels.com> References: <1419581126-12927-1-git-send-email-tiejun.chen@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: QEMU Trivial , Paolo Bonzini , QEMU Developers , kvm-devel To: Peter Maydell , Tiejun Chen Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On 26/12/14 13:00, Peter Maydell wrote: > On 26 December 2014 at 08:05, Tiejun Chen wrote: >> We should avoid to set irqfd{} unconditionally. >> >> Signed-off-by: Tiejun Chen > > Is there a hot path that we use this on such that the difference > in code order matters at all? > > thanks > -- PMM > IMHO the patch does not change anything even on hot-hot path. the declaration 'struct kvm_irqfd irqfd = {};' will result in memset inside. Thus in order to achieve declared goal author should declare struct kvm_irqfd irqfd; and perform memset(&irqfd, 0, sizeof(irqfd)); later after the check. Regards, Den From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58008) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y4RwT-0007bC-Ji for qemu-devel@nongnu.org; Fri, 26 Dec 2014 05:16:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y4RwQ-0002LU-E0 for qemu-devel@nongnu.org; Fri, 26 Dec 2014 05:16:21 -0500 Message-ID: <549D356A.4050506@parallels.com> Date: Fri, 26 Dec 2014 13:16:10 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1419581126-12927-1-git-send-email-tiejun.chen@intel.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] kvm_irqchip_assign_irqfd: just set irqfd in case of kvm_irqfds_enabled() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , Tiejun Chen Cc: QEMU Trivial , Paolo Bonzini , QEMU Developers , kvm-devel On 26/12/14 13:00, Peter Maydell wrote: > On 26 December 2014 at 08:05, Tiejun Chen wrote: >> We should avoid to set irqfd{} unconditionally. >> >> Signed-off-by: Tiejun Chen > > Is there a hot path that we use this on such that the difference > in code order matters at all? > > thanks > -- PMM > IMHO the patch does not change anything even on hot-hot path. the declaration 'struct kvm_irqfd irqfd = {};' will result in memset inside. Thus in order to achieve declared goal author should declare struct kvm_irqfd irqfd; and perform memset(&irqfd, 0, sizeof(irqfd)); later after the check. Regards, Den