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Daniel Borkmann 3024d95a4c bpf: Partially revert flexible-array member replacement
Partially revert 94dfc73e7c ("treewide: uapi: Replace zero-length arrays
with flexible-array members") given it breaks BPF UAPI.

For example, BPF CI run reveals build breakage under LLVM:

  [...]
    CLNG-BPF [test_maps] map_ptr_kern.o
    CLNG-BPF [test_maps] btf__core_reloc_arrays___diff_arr_val_sz.o
    CLNG-BPF [test_maps] test_bpf_cookie.o
  progs/map_ptr_kern.c:314:26: error: field 'trie_key' with variable sized type 'struct bpf_lpm_trie_key' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
           struct bpf_lpm_trie_key trie_key;
                                   ^
    CLNG-BPF [test_maps] btf__core_reloc_type_based___diff.o
  1 error generated.
  make: *** [Makefile:521: /tmp/runner/work/bpf/bpf/tools/testing/selftests/bpf/map_ptr_kern.o] Error 1
  make: *** Waiting for unfinished jobs....
  [...]

Typical usage of the bpf_lpm_trie_key is that the struct gets embedded into
a user defined key for the LPM BPF map, from the selftest example:

  struct bpf_lpm_trie_key {                 <-- UAPI exported struct
         __u32   prefixlen;
         __u8    data[];
  };

  struct lpm_key {                          <-- BPF program defined struct
         struct bpf_lpm_trie_key trie_key;
         __u32 data;
  };

Undo this for BPF until a different solution can be found. It's the only flexible-
array member case in the UAPI header.

This was discovered in BPF CI after Dave reported that the include/uapi/linux/bpf.h
header was out of sync with tools/include/uapi/linux/bpf.h after 94dfc73e7c. And
the subsequent sync attempt failed CI.

Fixes: 94dfc73e7c ("treewide: uapi: Replace zero-length arrays with flexible-array members")
Reported-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/bpf/22aebc88-da67-f086-e620-dd4a16e2bc69@iogearbox.net
2022-08-17 23:45:47 +02:00
Documentation Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
block block: convert to advancing variants of iov_iter_get_pages{,_alloc}() 2022-08-08 22:37:22 -04:00
certs Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
crypto crypto: blake2b: effectively disable frame size warning 2022-08-10 17:59:11 -07:00
drivers net: lan966x: fix checking for return value of platform_get_irq_byname() 2022-08-12 11:29:46 +01:00
fs New code for 6.0: 2022-08-11 13:11:49 -07:00
include bpf: Partially revert flexible-array member replacement 2022-08-17 23:45:47 +02:00
init Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
io_uring iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
lib iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
mm - hugetlb_vmemmap cleanups from Muchun Song 2022-08-10 11:18:00 -07:00
net skmsg: Fix wrong last sg check in sk_msg_recvmsg() 2022-08-17 22:33:20 +02:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts Revert "Makefile.extrawarn: re-enable -Wformat for clang" 2022-08-11 08:40:01 -07:00
security + Features 2022-08-10 10:53:22 -07:00
sound sound updates for 6.0-rc1 2022-08-06 10:19:51 -07:00
tools selftests/bpf: Add lru_bug to s390x deny list 2022-08-12 09:21:28 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Actually create debugfs in kvm_create_vm() 2022-08-10 15:08:28 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-10 18:29:34 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.