2d5ec1c66e
Allow to use bpf_program__set_attach_target to only set target attach program FD, while letting libbpf to use target attach function name from SEC() definition. This might be useful for some scenarios where bpf_object contains multiple related freplace BPF programs intended to replace different sub-programs in target BPF program. In such case all programs will have the same attach_prog_fd, but different attach_func_name. It's convenient to specify such target function names declaratively in SEC() definitions, but attach_prog_fd is a dynamic runtime setting. To simplify such scenario, allow bpf_program__set_attach_target() to delay BTF ID resolution till the BPF program load time by providing NULL attach_func_name. In that case the behavior will be similar to using bpf_object_open_opts.attach_prog_fd (which is marked deprecated since v0.7), but has the benefit of allowing more control by user in what is attached to what. Such setup allows having BPF programs attached to different target attach_prog_fd with target functions still declaratively recorded in BPF source code in SEC() definitions. Selftests changes in the next patch should make this more obvious. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210916015836.1248906-5-andrii@kernel.org
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.