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[80.230.39.63]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477a96aa472sm40401155e9.0.2025.11.19.01.32.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Nov 2025 01:32:23 -0800 (PST) Date: Wed, 19 Nov 2025 04:32:20 -0500 From: "Michael S. Tsirkin" To: Eugenio Perez Martin Cc: Jason Wang , Laurent Vivier , virtualization@lists.linux.dev, Maxime Coquelin , Cindy Lu , linux-kernel@vger.kernel.org, Yongji Xie , Xuan Zhuo , Stefano Garzarella Subject: Re: [PATCH v9 5/6] vduse: add vq group asid support Message-ID: <20251119042923-mutt-send-email-mst@kernel.org> References: <20251113115558.1277981-1-eperezma@redhat.com> <20251113115558.1277981-6-eperezma@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 19, 2025 at 10:26:43AM +0100, Eugenio Perez Martin wrote: > > But this is not the logic that is > > implemented in this patch as there's no synchronize_rcu() in the > > vduse_set_group_asid_nomsg(). > > We only set the pointer on the writer's side, we do nothing like > freeing resources. Should we set the pointer before or after > syncrhonize_rcu()? synchronize_rcu is called after writer makes it's changes. > What do we need to do on the other side of > syncrhonize_rcu()? Presumably, return so the caller knows the as has been updated. However, user-triggerable synchronize_rcu() is almost always a bug. If that's what is going on, you want srcu. -- MST