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2023-03-28docs: netlink: document the sub-type attribute propertyDonald Hunter
Add a definition for sub-type to the protocol spec doc and a description of its usage for C arrays in genetlink-legacy. Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-28docs: netlink: document struct support for genetlink-legacyDonald Hunter
Describe the genetlink-legacy support for using struct definitions for fixed headers and for binary attributes. Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-16ynl: broaden the license even moreJakub Kicinski
I relicensed Netlink spec code to GPL-2.0 OR BSD-3-Clause but we still put a slightly different license on the uAPI header than the rest of the code. Use the Linux-syscall-note on all the specs and all generated code. It's moot for kernel code, but should not hurt. This way the licenses match everywhere. Cc: Chuck Lever <chuck.lever@oracle.com> Fixes: 37d9df224d1e ("ynl: re-license uniformly under GPL-2.0 OR BSD-3-Clause") Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-07ynl: re-license uniformly under GPL-2.0 OR BSD-3-ClauseJakub Kicinski
I was intending to make all the Netlink Spec code BSD-3-Clause to ease the adoption but it appears that: - I fumbled the uAPI and used "GPL WITH uAPI note" there - it gives people pause as they expect GPL in the kernel As suggested by Chuck re-license under dual. This gives us benefit of full BSD freedom while fulfilling the broad "kernel is under GPL" expectations. Link: https://lore.kernel.org/all/20230304120108.05dd44c5@kernel.org/ Link: https://lore.kernel.org/r/20230306200457.3903854-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-03-03tools: ynl: use 1 as the default for first entry in attrs/opsJakub Kicinski
Pretty much all families use value: 1 or reserve as unspec the first entry in attribute set and the first operation. Make this the default. Update documentation (the doc for values of operations just refers back to doc for attrs so updating only attrs). Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-03-03tools: ynl: fully inherit attrs in subsetsJakub Kicinski
To avoid having to repeat the entire definition of an attribute (including the value) use the Attr object from the original set. In fact this is already the documented expectation. Fixes: be5bea1cc0bf ("net: add basic C code generators for Netlink") Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-01-31docs: netlink: add a starting guide for working with specsJakub Kicinski
We have a bit of documentation about the internals of Netlink and the specs, but really the goal is for most people to not worry about those. Add a practical guide for beginners who want to poke at the specs. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-01-31netlink: specs: finish up operation enum-modelsJakub Kicinski
I had a (bright?) idea of introducing the concept of enum-models to account for all the weird ways families enumerate their messages. I've never finished it because generating C code for each of them is pretty daunting. But for languages which can use ID values directly the support is simple enough, so clean this up a bit. "unified" model is what I recommend going forward. "directional" model is what ethtool uses. "notify-split" is used by the proposed DPLL code, but we can just make them use "unified", it hasn't been merged :) Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-01-24docs: add more netlink docs (incl. spec docs)Jakub Kicinski
Add documentation about the upcoming Netlink protocol specs. Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2022-09-29docs: netlink: clarify the historical baggage of Netlink flagsJakub Kicinski
nlmsg_flags are full of historical baggage, inconsistencies and strangeness. Try to document it more thoroughly. Explain the meaning of the ECHO flag (and while at it clarify the comment in the uAPI). Handwave a little about the NEW request flags and how they make sense on the surface but cater to really old paradigm before commands were a thing. I will add more notes on how to make use of ECHO and discouragement for reuse of flags to the kernel-side documentation. Link: https://lore.kernel.org/r/20220927212306.823862-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-30netlink: add support for ext_ack missing attributesJakub Kicinski
There is currently no way to report via extack in a structured way that an attribute is missing. This leads to families resorting to string messages. Add a pair of attributes - @offset and @type for machine-readable way of reporting missing attributes. The @offset points to the nest which should have contained the attribute, @type is the expected nla_type. The offset will be skipped if the attribute is missing at the message level rather than inside a nest. User space should be able to figure out which attribute enum (AKA attribute space AKA attribute set) the nest pointed to by @offset is using. Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2022-08-23docs: netlink: basic introduction to NetlinkJakub Kicinski
Provide a bit of a brain dump of netlink related information as documentation. Hopefully this will be useful to people trying to navigate implementing YAML based parsing in languages we won't be able to help with. I started writing this doc while trying to figure out what it'd take to widen the applicability of YAML to good old rtnl, but the doc grew beyond that as it usually happens. In all honesty a lot of this information is new to me as I usually follow the "copy an existing example, drink to forget" process of writing netlink user space, so reviews will be much appreciated. Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20220819200221.422801-2-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>