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

Commit Message

Jose E. Marchesi Feb. 6, 2024, 10:23 a.m. UTC

[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 <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: Yonghong Song <[e-mail]>
Cc: Eduard Zingerman <[e-mail]>
Cc: David Faust <[e-mail]>
Cc: Cupertino Miranda <[e-mail]>
---
 tools/testing/selftests/bpf/progs/test_cls_redirect.c        | 2 ++
 tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c | 2 ++
 tools/testing/selftests/bpf/progs/test_tc_tunnel.c           | 2 ++
 3 files changed, 6 insertions(+)

Comments

Yonghong Song Feb. 6, 2024, 4:15 p.m. UTC | #1

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 <[e-mail]>
> Cc: Andrii Nakryiko <[e-mail]>
> Cc: Yonghong Song <[e-mail]>
> Cc: Eduard Zingerman <[e-mail]>
> Cc: David Faust <[e-mail]>
> Cc: Cupertino Miranda <[e-mail]>

Acked-by: Yonghong Song <[e-mail]>

[e-mail] Feb. 6, 2024, 5:50 p.m. UTC | #2

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[e-mail]>:

On Tue,  6 Feb 2024 11:23:30 +0100 you 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.
> 
> [...]

Here is the summary with links:
  - [bpf-next,V3] bpf: use -Wno-address-of-packed-member in some selftests
    https://git.kernel.org/bpf/bpf-next/c/c27aa462aa78

You are awesome, thank you!

Patch

diff --git a/tools/testing/selftests/bpf/progs/test_cls_redirect.c b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
index 66b304982245..bfc9179259d5 100644
--- a/tools/testing/selftests/bpf/progs/test_cls_redirect.c
+++ b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
@@ -22,6 +22,8 @@ 
 
 #include "test_cls_redirect.h"
 
+#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
+
 #ifdef SUBPROGS
 #define INLINING __noinline
 #else
diff --git a/tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c b/tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c
index f41c81212ee9..da54c09e9a15 100644
--- a/tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c
+++ b/tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c
@@ -23,6 +23,8 @@ 
 #include "test_cls_redirect.h"
 #include "bpf_kfuncs.h"
 
+#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
+
 #define offsetofend(TYPE, MEMBER) \
 	(offsetof(TYPE, MEMBER) + sizeof((((TYPE *)0)->MEMBER)))
 
diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index e6e678aa9874..d8d7ab5e8e30 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -20,6 +20,8 @@ 
 #include <bpf/bpf_endian.h>
 #include <bpf/bpf_helpers.h>
 
+#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
+
 static const int cfg_port = 8000;
 
 static const int cfg_udp_src = 20000;