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Wed, 07 Jan 2026 01:47:59 -0800 (PST) Received: from [192.168.88.32] ([212.105.155.208]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d7f69e13bsm86823385e9.7.2026.01.07.01.47.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Jan 2026 01:47:58 -0800 (PST) Message-ID: <99b6f3f7-4130-436a-bfef-3ef35832e02c@redhat.com> Date: Wed, 7 Jan 2026 10:47:56 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v12 04/12] vsock: add netns support to virtio transports To: Bobby Eshleman Cc: Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman , Stefan Hajnoczi , "Michael S. Tsirkin" , Jason Wang , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Xuan Zhuo , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Bryan Tan , Vishnu Dasa , Broadcom internal kernel review list , Shuah Khan , linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kselftest@vger.kernel.org, berrange@redhat.com, Sargun Dhillon , Bobby Eshleman References: <20251126-vsock-vmtest-v12-0-257ee21cd5de@meta.com> <20251126-vsock-vmtest-v12-4-257ee21cd5de@meta.com> <6cef5a68-375a-4bb6-84f8-fccc00cf7162@redhat.com> <06b7cfea-d366-44f7-943e-087ead2f25c2@redhat.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 12/2/25 11:01 PM, Bobby Eshleman wrote: > On Tue, Dec 02, 2025 at 09:47:19PM +0100, Paolo Abeni wrote: >> I still have some concern WRT the dynamic mode change after netns >> creation. I fear some 'unsolvable' (or very hard to solve) race I can't >> see now. A tcp_child_ehash_entries-like model will avoid completely the >> issue, but I understand it would be a significant change over the >> current status. >> >> "Luckily" the merge window is on us and we have some time to discuss. Do >> you have a specific use-case for the ability to change the netns mode >> after creation? >> >> /P > > I don't think there is a hard requirement that the mode be change-able > after creation. Though I'd love to avoid such a big change... or at > least leave unchanged as much of what we've already reviewed as > possible. > > In the scheme of defining the mode at creation and following the > tcp_child_ehash_entries-ish model, what I'm imagining is: > - /proc/sys/net/vsock/child_ns_mode can be set to "local" or "global" > - /proc/sys/net/vsock/child_ns_mode is not immutable, can change any > number of times > > - when a netns is created, the new netns mode is inherited from > child_ns_mode, being assigned using something like: > > net->vsock.ns_mode = > get_net_ns_by_pid(current->pid)->child_ns_mode > > - /proc/sys/net/vsock/ns_mode queries the current mode, returning > "local" or "global", returning value of net->vsock.ns_mode > - /proc/sys/net/vsock/ns_mode and net->vsock.ns_mode are immutable and > reject writes > > Does that align with what you have in mind? Sorry for the latency. This fell of my radar while I still processed PW before EoY and afterwards I had some break. Yes, the above aligns with what I suggested, and I think it should solve possible race-related concerns (but I haven't looked at the RFC). /P