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[ Upstream commitd2836dddc9] When libbpf initializes the kernel's struct_ops in "bpf_map__init_kern_struct_ops()", it enforces all pointer types must be a function pointer and rejects others. It turns out to be too strict. For example, when directly using "struct tcp_congestion_ops" from vmlinux.h, it has a "struct module *owner" member and it is set to NULL in a bpf_tcp_cc.o. Instead, it only needs to ensure the member is a function pointer if it has been set (relocated) to a bpf-prog. This patch moves the "btf_is_func_proto(kern_mtype)" check after the existing "if (!prog) { continue; }". The original debug message in "if (!prog) { continue; }" is also removed since it is no longer valid. Beside, there is a later debug message to tell which function pointer is set. The "btf_is_func_proto(mtype)" has already been guaranteed in "bpf_object__collect_st_ops_relos()" which has been run before "bpf_map__init_kern_struct_ops()". Thus, this check is removed. v2: - Remove outdated debug message (Andrii) Remove because there is a later debug message to tell which function pointer is set. - Following mtype->type is no longer needed. Remove: "skip_mods_and_typedefs(btf, mtype->type, &mtype_id)" - Do "if (!prog)" test before skip_mods_and_typedefs. Fixes:590a008882("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210212021030.266932-1-kafai@fb.com Signed-off-by: Sasha Levin <sashal@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.