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Wed, 18 Feb 2026 10:11:11 -0800 (PST) Received: from localhost ([2a03:2880:25ff:49::]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-64c22fb1d22sm6051799d50.17.2026.02.18.10.11.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Feb 2026 10:11:11 -0800 (PST) From: Bobby Eshleman Subject: [PATCH net v2 0/3] vsock: add write-once semantics to child_ns_mode Date: Wed, 18 Feb 2026 10:10:35 -0800 Message-Id: <20260218-vsock-ns-write-once-v2-0-19e4c50d509a@meta.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="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAJwAlmkC/33NQQqDMBBA0auEWTsliWKjq96juEjjWIdiIklIW 8S7F3KArj+8f0CiyJRgFAdEKpw4eBiFbgS41fonIc8wCtBS91KrK5YU3At9wnfkTBi8IzSm7eb edCSthkbAHmnhT1Xv4CnD1AhYOeUQv/VUVE1/0aJQoVXLo5WLNoMdbhtle3Fhg+k8zx//dlzIu gAAAA== X-Change-ID: 20260217-vsock-ns-write-once-8834d684e0a2 To: Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Stefan Hajnoczi , Shuah Khan , Bobby Eshleman , "Michael S. Tsirkin" , Jonathan Corbet , Shuah Khan Cc: virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Daan De Meyer X-Mailer: b4 0.14.3 Two administrator processes may race when setting child_ns_mode: one sets it to "local" and creates a namespace, but another changes it to "global" in between. The first process ends up with a namespace in the wrong mode. Make child_ns_mode write-once so that a namespace manager can set it once, check the value, and be guaranteed it won't change before creating its namespaces. Writing a different value after the first write returns -EBUSY. One patch for the implementation, one for docs, and one for tests. --- Changes in v2: - break docs, tests, and implementation into separate patches - clarify commit message - only use child_ns_mode, do not add additional child_ns_mode_locked variable - add documentation to Documentation/ - Link to v1: https://lore.kernel.org/r/20260217-vsock-ns-write-once-v1-1-a1fb30f289a9@meta.com --- Bobby Eshleman (3): selftests/vsock: change tests to respect write-once child ns mode vsock: lock down child_ns_mode as write-once vsock: document write-once behavior of the child_ns_mode sysctl Documentation/admin-guide/sysctl/net.rst | 10 ++++++--- include/net/af_vsock.h | 20 +++++++++++++++--- include/net/netns/vsock.h | 9 +++++++- net/vmw_vsock/af_vsock.c | 15 +++++++++----- tools/testing/selftests/vsock/vmtest.sh | 35 +++++++++++++++----------------- 5 files changed, 58 insertions(+), 31 deletions(-) --- base-commit: ccd8e87748ad083047d6c8544c5809b7f96cc8df change-id: 20260217-vsock-ns-write-once-8834d684e0a2 Best regards, -- Bobby Eshleman