Re: include/linux/compiler_types.h:315:38: error: call to '__compiletime_assert_498' declared with attribute error: BUILD_BUG_ON failed: offsetof(struct can_frame, len) != offsetof(struct canfd_frame, len) || offsetof(struct can_frame, data) != offsetof(struc...

[Oliver Hartkopp]

Hello,

On 11.02.21 17:51, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   291009f656e8eaebbdfd3a8d99f6b190a9ce9deb
> commit: c7b74967799b1af52b3045d69d4c26836b2d41de can: replace can_dlc as variable/element for payload length
> date:   3 months ago
> config: arm-randconfig-r015-20210210 (attached as .config)
> compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>          chmod +x ~/bin/make.cross
>          # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c7b74967799b1af52b3045d69d4c26836b2d41de

This hash references to the commit ("can: replace can_dlc as 
variable/element for payload length") which makes a change to the 
BUILD_BUG_ON() content but this does not cause the root problem.

Going back some commits shows the commit ("can: add optional DLC element 
to Classical CAN frame structure") with hash

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ea7800565a128c1adafa1791ce80afd6016fe21c

is introducing the reported problem.

I assume BUILD_BUG_ON() does not work with the newly introduced union{} 
in struct can_frame in this specific (arm) architecture.

There are no compile issues like this on x86.

When removing the union{} from the struct can_frame and replacing it 
just with 'len' in the reported c7b74967799b1 commit, it compiles 
without problems.

Regards,
Oliver

>          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>          git fetch --no-tags linus master
>          git checkout c7b74967799b1af52b3045d69d4c26836b2d41de
>          # save the attached .config to linux build tree
>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All errors (new ones prefixed by >>):
>
>     In file included from <command-line>:
>     net/can/af_can.c: In function 'can_init':
> > > include/linux/compiler_types.h:315:38: error: call to '__compiletime_assert_498' declared with attribute error: BUILD_BUG_ON failed: offsetof(struct can_frame, len) != offsetof(struct canfd_frame, len) || offsetof(struct can_frame, data) != offsetof(struct canfd_frame, data)
>       315 |  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>           |                                      ^
>     include/linux/compiler_types.h:296:4: note: in definition of macro '__compiletime_assert'
>       296 |    prefix ## suffix();    \
>           |    ^~~~~~
>     include/linux/compiler_types.h:315:2: note: in expansion of macro '_compiletime_assert'
>       315 |  _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:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
>        50 |  BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
>           |  ^~~~~~~~~~~~~~~~
>     net/can/af_can.c:891:2: note: in expansion of macro 'BUILD_BUG_ON'
>       891 |  BUILD_BUG_ON(offsetof(struct can_frame, len) !=
>           |  ^~~~~~~~~~~~
>
>
> vim +/__compiletime_assert_498 +315 include/linux/compiler_types.h
>
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  301
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  302  #define _compiletime_assert(condition, msg, prefix, suffix) \
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  303  	__compiletime_assert(condition, msg, prefix, suffix)
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  304
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  305  /**
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  306   * compiletime_assert - break build and emit msg if condition is false
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  307   * @condition: a compile-time constant condition to check
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  308   * @msg:       a message to emit if condition is false
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  309   *
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  310   * In tradition of POSIX assert, this macro will break the build if the
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  311   * supplied condition is *false*, emitting the supplied error message if the
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  312   * compiler has support to do so.
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  313   */
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  314  #define compiletime_assert(condition, msg) \
> eb5c2d4b45e3d2 Will Deacon 2020-07-21 @315  	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> eb5c2d4b45e3d2 Will Deacon 2020-07-21  316
>
> :::::: The code at line 315 was first introduced by commit
> :::::: eb5c2d4b45e3d2d5d052ea6b8f1463976b1020d5 compiler.h: Move compiletime_assert() macros into compiler_types.h
>
> :::::: TO: Will Deacon <will@xxxxxxxxxx>
> :::::: CC: Will Deacon <will@xxxxxxxxxx>
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx