Re: [PATCH v3] bpf: Remove custom build rule

[Oleg Nesterov]

I know nothing about Kbuild, I can only confirm that this patch fixes the
problem I encountered in practice.

On 08/28, Alexey Gladkov wrote:
>
> $ touch kernel/bpf/core.c
> $ make C=2 CHECK=true kernel/bpf/core.o
>
> Outputs:
>
>   CHECK   scripts/mod/empty.c
>   CALL    scripts/checksyscalls.sh
>   DESCEND objtool
>   INSTALL libsubcmd_headers
>   CC      kernel/bpf/core.o
>
> As can be seen the compilation is done, but CHECK is not executed.

And after that

	$ make C=2 CHECK=true kernel/bpf/core.o
	  CHECK   scripts/mod/empty.c
	  CALL    scripts/checksyscalls.sh
	  DESCEND objtool
	  INSTALL libsubcmd_headers

CHECK is also not executed.

compare with, for example,

	$ touch kernel/trace/trace.c
	$ make C=2 CHECK=true kernel/trace/trace.o
	  CHECK   scripts/mod/empty.c
	  CALL    scripts/checksyscalls.sh
	  DESCEND objtool
	  INSTALL libsubcmd_headers
	  CC      kernel/trace/trace.o
	  CHECK   kernel/trace/trace.c
	$ make C=2 CHECK=true kernel/trace/trace.o
	  CHECK   scripts/mod/empty.c
	  CALL    scripts/checksyscalls.sh
	  DESCEND objtool
	  INSTALL libsubcmd_headers
	  CHECK   kernel/trace/trace.c

Tested-by: Oleg Nesterov <oleg@xxxxxxxxxx>