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[95.62.39.214]) by smtp.gmail.com with ESMTPSA id a15-20020a5d4d4f000000b002cfe685bfd6sm17960924wru.108.2023.04.12.12.16.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Apr 2023 12:16:38 -0700 (PDT) From: Juan Quintela To: Peter Xu Cc: qemu-devel@nongnu.org, Peter Maydell , Leonardo Bras Soares Passos , Daniel P . =?utf-8?Q?Berrang=C3=A9?= , "Dr . David Alan Gilbert" Subject: Re: [PATCH for-8.0 3/3] migration: Recover behavior of preempt channel creation for pre-7.2 In-Reply-To: <20230326172540.2571110-4-peterx@redhat.com> (Peter Xu's message of "Sun, 26 Mar 2023 13:25:40 -0400") References: <20230326172540.2571110-1-peterx@redhat.com> <20230326172540.2571110-4-peterx@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Date: Wed, 12 Apr 2023 21:16:36 +0200 Message-ID: <87cz48oqqz.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu wrote: > In 8.0 devel window we reworked preempt channel creation, so that there'll > be no race condition when the migration channel and preempt channel got > established in the wrong order in commit 5655aab079. > > However no one noticed that the change will also be not compatible with > older qemus, majorly 7.1/7.2 versions where preempt mode started to be > supported. > > Leverage the same pre-7.2 flag introduced in the previous patch to recover > the behavior hopefully before 8.0 releases, so we don't break migration > when we migrate from 8.0 to older qemu binaries. > > Fixes: 5655aab079 ("migration: Postpone postcopy preempt channel to be after main") > Signed-off-by: Peter Xu Reviewed-by: Juan Quintela queued.