Re: include/linux/compiler_types.h:397:45: error: call to '__compiletime_assert_810' declared with attribute error: BUILD_BUG_ON failed: skb_ext_total_length() > 255

[Thomas Weißschuh]

+Cc Arnd who was taking care of CFLAGS_GCOV in the past.

On 2023-12-17 19:39:34+0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   3b8a9b2e6809d281890dd0a1102dc14d2cd11caf
> commit: 5d21d0a65b573507bae774708199328b38dedfe6 net: generalize calculation of skb extensions length
> date:   4 months ago
> config: um-randconfig-r025-20230617 (https://download.01.org/0day-ci/archive/20231217/202312171924.4FozI5FG-lkp@xxxxxxxxx/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231217/202312171924.4FozI5FG-lkp@xxxxxxxxx/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202312171924.4FozI5FG-lkp@xxxxxxxxx/
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from <command-line>:
>    In function 'skb_extensions_init',
>        inlined from 'skb_init' at net/core/skbuff.c:4848:2:
> >> include/linux/compiler_types.h:397:45: error: call to '__compiletime_assert_810' declared with attribute error: BUILD_BUG_ON failed: skb_ext_total_length() > 255
>      397 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>          |                                             ^
>    include/linux/compiler_types.h:378:25: note: in definition of macro '__compiletime_assert'
>      378 |                         prefix ## suffix();                             \
>          |                         ^~~~~~
>    include/linux/compiler_types.h:397:9: note: in expansion of macro '_compiletime_assert'
>      397 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>          |         ^~~~~~~~~~~~~~~~~~~
>    include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
>       39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>          |                                     ^~~~~~~~~~~~~~~~~~
>    include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
>       50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
>          |         ^~~~~~~~~~~~~~~~
>    net/core/skbuff.c:4800:9: note: in expansion of macro 'BUILD_BUG_ON'
>     4800 |         BUILD_BUG_ON(skb_ext_total_length() > 255);
>          |         ^~~~~~~~~~~~

[..]

This seems to be a compiler bug/configuration issue.

When I remove the entry for SKB_EXT_MCTP from skb_ext_type_len then the
error goes away. However this entry works the same as all other entries.

Also dropping -fno-tree-loop-im *or* -fprofile-arcs from CFLAGS_GCOV
makes the code compile as-is.

Or switching to a 64bit build...


Thomas