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Tsirkin" , Parav Pandit Cc: "virtualization@lists.linux.dev" , "jasowang@redhat.com" , "stefanha@redhat.com" , "pbonzini@redhat.com" , "xuanzhuo@linux.alibaba.com" , "stable@vger.kernel.org" , Max Gurtovoy , "NBU-Contact-Li Rongqing (EXTERNAL)" Subject: Re: [PATCH] Revert "virtio_pci: Support surprise removal of virtio pci device" In-Reply-To: <20250827061537-mutt-send-email-mst@kernel.org> Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Avril Crosse O'Flaherty" References: <20250822091706.21170-1-parav@nvidia.com> <20250822060839-mutt-send-email-mst@kernel.org> <20250822090249-mutt-send-email-mst@kernel.org> <20250822095225-mutt-send-email-mst@kernel.org> <20250824102947-mutt-send-email-mst@kernel.org> <20250827061537-mutt-send-email-mst@kernel.org> User-Agent: Notmuch/0.38.3 (https://notmuchmail.org) Date: Wed, 27 Aug 2025 13:33:37 +0200 Message-ID: <87frdddmni.fsf@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On Wed, Aug 27 2025, "Michael S. Tsirkin" wrote: > On Tue, Aug 26, 2025 at 06:52:03PM +0000, Parav Pandit wrote: >> > What I do not understand, is what good does the revert do. Sorry. >> > >> Let me explain. >> It prevents the issue of vblk requests being stuck due to broken VQ. >> It prevents the vnet driver start_xmit() to be not stuck on skb completions. > > This is the part I don't get. In what scenario, before 43bb40c5b9265 > start_xmit is not stuck, but after 43bb40c5b9265 it is stuck? > > Once the device is gone, it is not using any buffers at all. What I also don't understand: virtio-ccw does exactly the same thing (virtio_break_device(), added in 2014), and it supports surprise removal _only_, yet I don't remember seeing bug reports?