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[2003:cf:d740:65dc:b9e8:48d5:8408:b27]) by smtp.gmail.com with ESMTPSA id u7-20020a056000038700b0033b5730d6aasm2320272wrf.10.2024.02.09.08.51.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Feb 2024 08:51:19 -0800 (PST) Message-ID: <272941d6-fb76-4c5c-968e-d441c7957646@redhat.com> Date: Fri, 9 Feb 2024 17:51:18 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] block: Allow concurrent BB context changes To: Michael Tokarev , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org, Stefan Hajnoczi , Kevin Wolf , Paolo Bonzini , Fam Zheng References: <20240202144755.671354-1-hreitz@redhat.com> <9bc07eef-da55-4ebf-a4ee-1d55eb6fd921@tls.msk.ru> Content-Language: en-US From: Hanna Czenczek In-Reply-To: <9bc07eef-da55-4ebf-a4ee-1d55eb6fd921@tls.msk.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.269, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 09.02.24 15:08, Michael Tokarev wrote: > 02.02.2024 17:47, Hanna Czenczek : >> Hi, >> >> Without the AioContext lock, a BB's context may kind of change at any >> time (unless it has a root node, and I/O requests are pending). That >> also means that its own context (BlockBackend.ctx) and that of its root >> node can differ sometimes (while the context is being changed). > > How relevant this is for -stable (8.2 at least) which does not have > "scsi: eliminate AioContext lock" patchset, and in particular,: > v8.2.0-124-geaad0fe260 "scsi: only access SCSIDevice->requests from > one thread"? > > The issue first patch "block-backend: Allow concurrent context changes" > fixes (RHEL-19381) seems to be for 8.1.something, so it exists in 8.2 > too, and this particular fix applies to 8.2. > > But with other changes around all this, I'm a bit lost as of what should > be done on stable.  Not even thinking about 7.2 here :) Ah, sorry, yes.  Since we do still have the AioContext lock, this series won’t be necessary in -stable.  Sorry for the noise! Hanna