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[184.145.4.219]) by smtp.gmail.com with ESMTPSA id x194sm146583qkb.79.2021.05.26.14.58.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 14:58:59 -0700 (PDT) Date: Wed, 26 May 2021 17:58:58 -0400 From: Peter Xu To: Lukas Straub Subject: Re: [PATCH 1/1] yank: Unregister function when using TLS migration Message-ID: References: <20210526200540.1088333-1-leobras.c@gmail.com> <20210526232103.39e2a7d0@gecko.fritz.box> MIME-Version: 1.0 In-Reply-To: <20210526232103.39e2a7d0@gecko.fritz.box> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.371, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Leonardo Bras , "Daniel P. Berrange" , "Dr. David Alan Gilbert" , Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, May 26, 2021 at 11:21:03PM +0200, Lukas Straub wrote: > On Wed, 26 May 2021 16:40:35 -0400 > Peter Xu wrote: > > > On Wed, May 26, 2021 at 05:05:40PM -0300, Leonardo Bras wrote: > > > After yank feature was introduced, whenever migration is started using TLS, > > > the following error happens in both source and destination hosts: > > > > > > (qemu) qemu-kvm: ../util/yank.c:107: yank_unregister_instance: > > > Assertion `QLIST_EMPTY(&entry->yankfns)' failed. > > > > > > This happens because of a missing yank_unregister_function() when using > > > qio-channel-tls. > > > > > > Fix this by also allowing TYPE_QIO_CHANNEL_TLS object type to perform > > > yank_unregister_function() in channel_close() and multifd_load_cleanup(). > > > > > > Fixes: 50186051f ("Introduce yank feature") > > > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1964326 > > > Signed-off-by: Leonardo Bras > > > > Leo, > > > > Thanks for looking into it! > > > > So before looking int the fix... I do have a doubt on why we only enable yank > > on socket typed, as I think tls should also work with qio_channel_shutdown(). > > > > IIUC the confused thing here is we register only for qio-socket, however tls > > will actually call migration_channel_connect() twice, first with a qio-socket, > > then with the real tls-socket. For tls I feel like we have registered with the > > wrong channel - instead of the wrapper socket ioc, we should register to the > > final tls ioc? > > > > Lukas, is there a reason? > > > > Hi, > There is no specific reason. Both ways work equally well in preventing > qemu from hanging. shutdown() for tls-channel just makes it abort a > little sooner (by not attempting to encrypt and send data anymore). > > I don't lean either way. I guess registering it on the tls-channel > makes is a bit more explicit and clearer. Agreed, because IMHO logically the migration code should not be aware of internals of IOChannels, e.g., we shouldn't need to know ioc->master is the socket ioc of tls ioc to unregister. -- Peter Xu