Fwd: stable kernels 6.6.23 and 6.1.83 fails to build: error: unknown type name 'u32'

Hi,

On Bugzilla, ncopa@alpinelinux.org reported resolve_btfids FTBFS regression on musl system [1]:

The latest releases fails to build with musl libc (Alpine Linux edge and v3.19):

rm -f -f /home/ncopa/aports/main/linux-lts/src/build-lts.x86_64/tools/bpf/resolve_btfids/libbpf/libbpf.a; ar rcs /home/ncopa/aports/main/linux-lts/src/build-lts.x86_64/tool
s/bpf/resolve_btfids/libbpf/libbpf.a /home/ncopa/aports/main/linux-lts/src/build-lts.x86_64/tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf-in.o
In file included from main.c:73:
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:7:9: error: unknown type name 'u32'
    7 |         u32 cnt;                                                              
      |         ^~~                
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:8:9: error: unknown type name 'u32'
    8 |         u32 ids[];         
      |         ^~~                    
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:12:9: error: unknown type name 'u32'
   12 |         u32 cnt;   
      |         ^~~                        
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:13:9: error: unknown type name 'u32'
   13 |         u32 flags;
      |         ^~~
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:15:17: error: unknown type name 'u32'
   15 |                 u32 id;
      |                 ^~~
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:16:17: error: unknown type name 'u32'
   16 |                 u32 flags;
      |                 ^~~
/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/include/linux/btf_ids.h:215:8: error: unknown type name 'u32'
  215 | extern u32 btf_tracing_ids[];
      |        ^~~
make[4]: *** [/home/ncopa/aports/main/linux-lts/src/linux-6.6/tools/build/Makefile.build:98: /home/ncopa/aports/main/linux-lts/src/build-lts.x86_64/tools/bpf/resolve_btfids
/main.o] Error 1
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [Makefile:83: /home/ncopa/aports/main/linux-lts/src/build-lts.x86_64/tools/bpf/resolve_btfids//resolve_btfids-in.o] Error 2
make[2]: *** [Makefile:76: bpf/resolve_btfids] Error 2
make[1]: *** [/home/ncopa/aports/main/linux-lts/src/linux-6.6/Makefile:1354: tools/bpf/resolve_btfids] Error 2
make: *** [/home/ncopa/aports/main/linux-lts/src/linux-6.6/Makefile:234: __sub-make] Error 2

Bisection led to upstream commit 9707ac4fe2f5ba ("tools/resolve_btfids: Refactor set sorting with types from btf_ids.h") as the culprit.

See the report on Bugzilla for the full thread and proposed fix.

Thanks.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=218647