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[80.230.39.63]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477b1037d32sm31884905e9.12.2025.11.18.23.53.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Nov 2025 23:53:39 -0800 (PST) Date: Wed, 19 Nov 2025 02:53:36 -0500 From: "Michael S. Tsirkin" To: Daniel Jurgens Cc: netdev@vger.kernel.org, jasowang@redhat.com, pabeni@redhat.com, virtualization@lists.linux.dev, parav@nvidia.com, shshitrit@nvidia.com, yohadt@nvidia.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, jgg@ziepe.ca, kevin.tian@intel.com, kuba@kernel.org, andrew+netdev@lunn.ch, edumazet@google.com Subject: Re: [PATCH net-next v11 05/12] virtio_net: Query and set flow filter caps Message-ID: <20251119024647-mutt-send-email-mst@kernel.org> References: <20251118143903.958844-1-danielj@nvidia.com> <20251118143903.958844-6-danielj@nvidia.com> Precedence: bulk X-Mailing-List: netdev@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: <20251118143903.958844-6-danielj@nvidia.com> On Tue, Nov 18, 2025 at 08:38:55AM -0600, Daniel Jurgens wrote: > +/** > + * struct virtio_net_ff_cap_data - Flow filter resource capability limits > + * @groups_limit: maximum number of flow filter groups supported by the device > + * @classifiers_limit: maximum number of classifiers supported by the device > + * @rules_limit: maximum number of rules supported device-wide across all groups > + * @rules_per_group_limit: maximum number of rules allowed in a single group > + * @last_rule_priority: priority value associated with the lowest-priority rule > + * @selectors_per_classifier_limit: maximum selectors allowed in one classifier > + * > + * The limits are reported by the device and describe resource capacities for > + * flow filters. This sentence adds nothing of substance. Pls don't add fluff like this in comments. > Multi-byte fields are little-endian. You do not really need to say "Multi-byte fields are little-endian." do you? It says __le explicitly. Same applies to all structures. > + */ > +struct virtio_net_ff_cap_data { > + __le32 groups_limit; > + __le32 classifiers_limit; > + __le32 rules_limit; > + __le32 rules_per_group_limit; > + __u8 last_rule_priority; > + __u8 selectors_per_classifier_limit; > +}; so the compiler adds 2 bytes of padding here. The bug is in the spec. I think this happens to work for people because controllers either also added 2 bytes of padding here at the end, or they report a shorter structure and the spec says commands can be truncated. So I think we can just add 2 bytes of padding at the end and it will be harmless. It is a spec extension, but a minor one. -- MST