Re: [PATCH bpf-next V3] bpf: use -Wno-address-of-packed-member in some selftests

[Yonghong Song <yonghong.song@linux.dev>]

On 2/6/24 2:23 AM, Jose E. Marchesi wrote:
> [Differences from V2:
> - Remove conditionals in the source files pragmas, as the
>    pragma is supported by both GCC and clang.]
>
> Both GCC and clang implement the -Wno-address-of-packed-member
> warning, which is enabled by -Wall, that warns about taking the
> address of a packed struct field when it can lead to an "unaligned"
> address.
>
> This triggers the following errors (-Werror) when building three
> particular BPF selftests with GCC:
>
>    progs/test_cls_redirect.c
>    986 |         if (ipv4_is_fragment((void *)&encap->ip)) {
>    progs/test_cls_redirect_dynptr.c
>    410 |         pkt_ipv4_checksum((void *)&encap_gre->ip);
>    progs/test_cls_redirect.c
>    521 |         pkt_ipv4_checksum((void *)&encap_gre->ip);
>    progs/test_tc_tunnel.c
>     232 |         set_ipv4_csum((void *)&h_outer.ip);
>
> These warnings do not signal any real problem in the tests as far as I
> can see.
>
> This patch adds pragmas to these test files that inhibit the
> -Waddress-of-packed-member warning.
>
> Tested in bpf-next master.
> No regressions.
>
> Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Yonghong Song <yhs@meta.com>
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: David Faust <david.faust@oracle.com>
> Cc: Cupertino Miranda <cupertino.miranda@oracle.com>

Acked-by: Yonghong Song <yonghong.song@linux.dev>