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Introduce 4 new netlink-based XDP APIs for attaching, detaching, and querying XDP programs: - bpf_xdp_attach; - bpf_xdp_detach; - bpf_xdp_query; - bpf_xdp_query_id. These APIs replace bpf_set_link_xdp_fd, bpf_set_link_xdp_fd_opts, bpf_get_link_xdp_id, and bpf_get_link_xdp_info APIs ([0]). The latter don't follow a consistent naming pattern and some of them use non-extensible approaches (e.g., struct xdp_link_info which can't be modified without breaking libbpf ABI). The approach I took with these low-level XDP APIs is similar to what we did with low-level TC APIs. There is a nice duality of bpf_tc_attach vs bpf_xdp_attach, and so on. I left bpf_xdp_attach() to support detaching when -1 is specified for prog_fd for generality and convenience, but bpf_xdp_detach() is preferred due to clearer naming and associated semantics. Both bpf_xdp_attach() and bpf_xdp_detach() accept the same opts struct allowing to specify expected old_prog_fd. While doing the refactoring, I noticed that old APIs require users to specify opts with old_fd == -1 to declare "don't care about already attached XDP prog fd" condition. Otherwise, FD 0 is assumed, which is essentially never an intended behavior. So I made this behavior consistent with other kernel and libbpf APIs, in which zero FD means "no FD". This seems to be more in line with the latest thinking in BPF land and should cause less user confusion, hopefully. For querying, I left two APIs, both more generic bpf_xdp_query() allowing to query multiple IDs and attach mode, but also a specialization of it, bpf_xdp_query_id(), which returns only requested prog_id. Uses of prog_id returning bpf_get_link_xdp_id() were so prevalent across selftests and samples, that it seemed a very common use case and using bpf_xdp_query() for doing it felt very cumbersome with a highly branches if/else chain based on flags and attach mode. Old APIs are scheduled for deprecation in libbpf 0.8 release. [0] Closes: https://github.com/libbpf/libbpf/issues/309 Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/r/20220120061422.2710637-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.