From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH v3 39/41] xen/events: use virt_xxx barriers Date: Mon, 11 Jan 2016 11:12:06 +0000 Message-ID: <56938E06.9050702@citrix.com> References: <1452426622-4471-1-git-send-email-mst@redhat.com> <1452426622-4471-40-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1452426622-4471-40-git-send-email-mst@redhat.com> Sender: linux-ia64-owner@vger.kernel.org To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , Russell King - ARM Linux , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Joe Perches , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenpro List-Id: linux-arch.vger.kernel.org On 10/01/16 14:21, Michael S. Tsirkin wrote: > drivers/xen/events/events_fifo.c uses rmb() to communicate with the > other side. > > For guests compiled with CONFIG_SMP, smp_rmb would be sufficient, so > rmb() here is only needed if a non-SMP guest runs on an SMP host. > > Switch to the virt_rmb barrier which serves this exact purpose. > > Pull in asm/barrier.h here to make sure the file is self-contained. > > Suggested-by: David Vrabel > Signed-off-by: Michael S. Tsirkin Acked-by: David Vrabel David From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp02.citrix.com ([66.165.176.63]:50154 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759544AbcAKLMN (ORCPT ); Mon, 11 Jan 2016 06:12:13 -0500 Message-ID: <56938E06.9050702@citrix.com> Date: Mon, 11 Jan 2016 11:12:06 +0000 From: David Vrabel MIME-Version: 1.0 Subject: Re: [PATCH v3 39/41] xen/events: use virt_xxx barriers References: <1452426622-4471-1-git-send-email-mst@redhat.com> <1452426622-4471-40-git-send-email-mst@redhat.com> In-Reply-To: <1452426622-4471-40-git-send-email-mst@redhat.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , Russell King - ARM Linux , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Joe Perches , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org, Konrad Rzeszutek Wilk , Boris Ostrovsky , Julien Grall , Ross Lagerwall , Stefano Stabellini , Wei Liu Message-ID: <20160111111206.7aA1MsaWEULyVLJL2oY-AEGMJWEA2V9hrlE5Q-pWvNo@z> On 10/01/16 14:21, Michael S. Tsirkin wrote: > drivers/xen/events/events_fifo.c uses rmb() to communicate with the > other side. > > For guests compiled with CONFIG_SMP, smp_rmb would be sufficient, so > rmb() here is only needed if a non-SMP guest runs on an SMP host. > > Switch to the virt_rmb barrier which serves this exact purpose. > > Pull in asm/barrier.h here to make sure the file is self-contained. > > Suggested-by: David Vrabel > Signed-off-by: Michael S. Tsirkin Acked-by: David Vrabel David