Subject: RE: [Intel-wired-lan] [PATCH] virtchnl: Add missing explicit padding to structures

From: "Bowers, AndrewX" <[email-masked]>
Date: Wed, 22 Apr 2020 18:50:26 +0000

-----Original Message-----
From: Intel-wired-lan <[email-masked]> On Behalf Of Geert Uytterhoeven
Sent: Thursday, April 16, 2020 2:51 AM
To: Kirsher, Jeffrey T <[email-masked]>; David S . Miller <[email-masked]>
Cc: [email-masked]; [email-masked]; [email-masked]; Geert Uytterhoeven <[email-masked]>
Subject: [Intel-wired-lan] [PATCH] virtchnl: Add missing explicit padding to structures

On e.g. m68k, the alignment of 32-bit values is only 2 bytes, leading
to:

    ./include/linux/avf/virtchnl.h:147:36: warning: division by zero [-Wdiv-by-zero]
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
					^
    ./include/linux/avf/virtchnl.h:577:1: note: in expansion of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
     VIRTCHNL_CHECK_STRUCT_LEN(272, virtchnl_filter);
     ^~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:577:32: error: enumerator value for ‘virtchnl_static_assert_virtchnl_filter’ is not an integer constant
     VIRTCHNL_CHECK_STRUCT_LEN(272, virtchnl_filter);
				    ^~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:147:53: note: in definition of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
							 ^
    ./include/linux/avf/virtchnl.h:147:36: warning: division by zero [-Wdiv-by-zero]
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
					^
    ./include/linux/avf/virtchnl.h:619:1: note: in expansion of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
     VIRTCHNL_CHECK_STRUCT_LEN(16, virtchnl_pf_event);
     ^~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:619:31: error: enumerator value for ‘virtchnl_static_assert_virtchnl_pf_event’ is not an integer constant
     VIRTCHNL_CHECK_STRUCT_LEN(16, virtchnl_pf_event);
				   ^~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:147:53: note: in definition of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
							 ^
    ./include/linux/avf/virtchnl.h:147:36: warning: division by zero [-Wdiv-by-zero]
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
					^
    ./include/linux/avf/virtchnl.h:640:1: note: in expansion of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
     VIRTCHNL_CHECK_STRUCT_LEN(12, virtchnl_iwarp_qv_info);
     ^~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:640:31: error: enumerator value for ‘virtchnl_static_assert_virtchnl_iwarp_qv_info’ is not an integer constant
     VIRTCHNL_CHECK_STRUCT_LEN(12, virtchnl_iwarp_qv_info);
				   ^~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:147:53: note: in definition of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
							 ^
    ./include/linux/avf/virtchnl.h:147:36: warning: division by zero [-Wdiv-by-zero]
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
					^
    ./include/linux/avf/virtchnl.h:647:1: note: in expansion of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
     VIRTCHNL_CHECK_STRUCT_LEN(16, virtchnl_iwarp_qvlist_info);
     ^~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:647:31: error: enumerator value for ‘virtchnl_static_assert_virtchnl_iwarp_qvlist_info’ is not an integer constant
     VIRTCHNL_CHECK_STRUCT_LEN(16, virtchnl_iwarp_qvlist_info);
				   ^~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/avf/virtchnl.h:147:53: note: in definition of macro ‘VIRTCHNL_CHECK_STRUCT_LEN’
      { virtchnl_static_assert_##X = (n)/((sizeof(struct X) == (n)) ? 1 : 0) }
							 ^

Fix this by adding explicit padding to structures with holes.

Reported-by: [email-masked]
Signed-off-by: Geert Uytterhoeven <[email-masked]>
---
Exposed by the "select PCI" in commit 4be5e8648b0c287a ("media: move CEC platform drivers to a separate directory").
---
 include/linux/avf/virtchnl.h | 5 +++++
 1 file changed, 5 insertions(+)

Tested-by: Andrew Bowers <[email-masked]>