[DTrace-devel] [PATCH] bpf/Build: spurious fail of test compile is not detected

[Kris Van Hees]

Thanks for this patch.  I already had the same fix queued up on 2.0-branch-dev
for pushing so I added your Signed-off-by and the Orabug to the patch I already
had.

Funny thing is that this problem would only show up when you do a non-SMP
build (which is why I didn't see it earlier).

On Wed, Oct 14, 2020 at 04:10:11PM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> In bpf/Build, the bpf-check target checks for an old version of the BPF cross
> compiler.  There are two problems:
> 
> - The rule is executed before some essential links are set up.  Therefore,
>   the compile always fails, emitting the error message:
> 
>     bpf/get_bvar.c:5:10: fatal error: linux/bpf.h: No such file or directory
>      #include <linux/bpf.h>
>               ^~~~~~~~~~~~~
>     compilation terminated.
> 
> - Because no assembly output is generated, the check never sees an error.
> 
> The first problem can be solved by introducing a dependency in the make rules
> such that the links will be created before the bpf-check rule is executed.
> 
> The second problem is not that important since, if there truly is a compilation
> problem, the actual compilation of the file in question will error out.
> 
> Orabug: 32016090
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  bpf/Build | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/bpf/Build b/bpf/Build
> index ee41f221..bd7683e0 100644
> --- a/bpf/Build
> +++ b/bpf/Build
> @@ -27,7 +27,7 @@ bpf_dlib_SOURCES = \
>  	get_tvar.c set_tvar.c \
>  	memcpy.c strnlen.c
>  
> -bpf-check:
> +bpf-check: $(objdir)/include/.dir.stamp
>  	$(BPFC) $(BPFCPPFLAGS) $(bpf_dlib_CPPFLAGS) $(BPFCFLAGS) -S \
>  		-o - bpf/get_bvar.c | \
>  		awk '/dt_get_bvar:/ { \
> -- 
> 2.18.4
> 
> 
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