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[80.230.68.31]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47aa0960af0sm21194916f8f.30.2026.07.06.01.44.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jul 2026 01:44:01 -0700 (PDT) Date: Mon, 6 Jul 2026 04:43:59 -0400 From: "Michael S. Tsirkin" To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Adam Litke , Rusty Russell , virtualization@lists.linux.dev, Andrew Morton , linux-mm@kvack.org Subject: Re: [PATCH v2] virtio_balloon: prime stats vq after virtio_device_ready() Message-ID: <20260706044122-mutt-send-email-mst@kernel.org> References: <2f0d0de033f3005d3b985883be3e5cf37b3f6c42.1783278596.git.mst@redhat.com> <13794c5e-375a-4fc5-84b4-a637d077f8a0@kernel.org> <20260706042207-mutt-send-email-mst@kernel.org> <6b8e4ad3-6909-4d0a-89a4-104a5ad9fe79@kernel.org> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <6b8e4ad3-6909-4d0a-89a4-104a5ad9fe79@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ypcp0NqWW9xjmZDRcvTAYGrgYzkgRfXFV4w1W_duh0U_1783327443 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Jul 06, 2026 at 10:38:18AM +0200, David Hildenbrand (Arm) wrote: > >>> - virtqueue_kick(vb->stats_vq); > >>> + disable_work(&vb->update_balloon_stats_work); > >> > >> That's to stop the stats queue triggering stats_request() I assume? > > > > Yes. > > > >> Is that > >> valid before we actually added+kicked ourselves? > > > > Why not? > > I was wondering whether the spec would state something about that. Sorry I do not get the question. Virtio API expects callers to serialize calls for each VQ. So this just prevents the work from running and accessing the VQ while probe calls add_buf/kick. I'll add a comment explaining that. But it has nothing to do with the spec. > > > >> Also, can't we simply handle that in stats_request(), just ignoring it there? > > > > Then we'd need to maintain a special flag and I dislike that. > > I was hoping that we could use the device-ready indication, but there would be a > small race window indeed. > > -- > Cheers, > > David