1a11a4c74f
Add bpf_map__resize() to change max_entries for a map. Quite often necessary map size is unknown at compile time and can be calculated only at run time. Currently the following approach is used to do so: * bpf_object__open_buffer() to open Elf file from a buffer; * bpf_object__find_map_by_name() to find relevant map; * bpf_map__def() to get map attributes and create struct bpf_create_map_attr from them; * update max_entries in bpf_create_map_attr; * bpf_create_map_xattr() to create new map with updated max_entries; * bpf_map__reuse_fd() to replace the map in bpf_object with newly created one. And after all this bpf_object can finally be loaded. The map will have new size. It 1) is quite a lot of steps; 2) doesn't take BTF into account. For "2)" even more steps should be made and some of them require changes to libbpf (e.g. to get struct btf * from bpf_object). Instead the whole problem can be solved by introducing simple bpf_map__resize() API that checks the map and sets new max_entries if the map is not loaded yet. So the new steps are: * bpf_object__open_buffer() to open Elf file from a buffer; * bpf_object__find_map_by_name() to find relevant map; * bpf_map__resize() to update max_entries. That's much simpler and works with BTF. Signed-off-by: Andrey Ignatov <rdna@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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.