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[80.230.34.155]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4832040a3cesm68665225e9.3.2026.02.07.01.56.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Feb 2026 01:56:16 -0800 (PST) Date: Sat, 7 Feb 2026 04:56:13 -0500 From: "Michael S. Tsirkin" To: Jakub Kicinski Cc: Srujana Challa , netdev@vger.kernel.org, virtualization@lists.linux.dev, pabeni@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, davem@davemloft.net, edumazet@google.com, ndabilpuram@marvell.com, kshankar@marvell.com Subject: Re: [PATCH v2 net-next] virtio_net: Improve RSS key size validation and use NETDEV_RSS_KEY_LEN Message-ID: <20260207045416-mutt-send-email-mst@kernel.org> References: <20260206120154.2548079-1-schalla@marvell.com> <20260206191308.7fdbfef4@kernel.org> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260206191308.7fdbfef4@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 7aUuafVt-ZYEfz_siVPXglaWUSLx5Y3TqRU1PGGi6Jc_1770458178 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Feb 06, 2026 at 07:13:08PM -0800, Jakub Kicinski wrote: > On Fri, 6 Feb 2026 17:31:54 +0530 Srujana Challa wrote: > > Replace hardcoded RSS max key size limit with NETDEV_RSS_KEY_LEN to > > align with kernel's standard RSS key length. Add validation for RSS > > key size against spec minimum (40 bytes) and driver maximum. When > > validation fails, gracefully disable RSS features and continue > > initialization rather than failing completely. > > Hm, FWIW clang says: > > drivers/net/virtio_net.c:6841:31: warning: result of comparison of constant 256 with expression of type 'u8' (aka 'unsigned char') is always false [-Wtautological-constant-out-of-range-compare] > 6841 | } else if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) { > | ~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Which is kinda annoying because the value was increased in net-next. > If Machael wants this backported then we need to keep the check > and follow up in net-next? We could try to cast the u32 away but > that feels dirty.. I'd say yes. the warning is harmless. so patch 1 - this code patch 2 - replace with BUILD_BUG_ON but i ask then whether this code was actually tested against net-next. -- MST