From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH v3 08/10] migration: handle the error condition properly Date: Wed, 8 Aug 2018 15:23:22 +0800 Message-ID: <4c3ebdce-8c4e-8cb4-4dfe-384489224343@gmail.com> References: <20180807091209.13531-1-xiaoguangrong@tencent.com> <20180807091209.13531-9-xiaoguangrong@tencent.com> <20180808050846.GG24415@xz-mi> <503d7733-e2e7-09c5-75a3-1e250f549065@gmail.com> <20180808065619.GK24415@xz-mi> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, mst@redhat.com, mtosatti@redhat.com, Xiao Guangrong , dgilbert@redhat.com, qemu-devel@nongnu.org, wei.w.wang@intel.com, jiang.biao2@zte.com.cn, pbonzini@redhat.com To: Peter Xu Return-path: In-Reply-To: <20180808065619.GK24415@xz-mi> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Id: kvm.vger.kernel.org On 08/08/2018 02:56 PM, Peter Xu wrote: > On Wed, Aug 08, 2018 at 02:29:52PM +0800, Xiao Guangrong wrote: >> >> >> On 08/08/2018 01:08 PM, Peter Xu wrote: >>> On Tue, Aug 07, 2018 at 05:12:07PM +0800, guangrong.xiao@gmail.com wrote: >>>> From: Xiao Guangrong >>>> >>>> ram_find_and_save_block() can return negative if any error hanppens, >>>> however, it is completely ignored in current code >>> >>> Could you hint me where we'll return an error? >>> >> >> I think control_save_page() may return a error condition but i am not >> good at it ... Other places look safe _currently_. These functions were >> designed to have error returned anyway. > > Ah, the RDMA codes... > > Then I feel like this patch would be more suitable to be put into some > of the RDMA series - at least we'd better be clear about what errors > we're going to capture. For non-RDMA, it seems a bit helpless after > all - AFAIU we're depending on the few qemu_file_get_error() calls to > detect output errors. So, are you talking about to modify the semantic of these functions, ram_save_host_page(), ram_save_target_page(), etc, and make them be: "Returns the number of pages written where zero means no dirty pages, error conditions are indicated in the QEMUFile @rs->file if it happened." If it's what you want, i will update the comments and make the implementation more clear to reflect this fact for these functions