Re: [linux-next:master 12987/13499] include/linux/build_bug.h:78:41: error: static assertion failed: "SKB_WITH_OVERHEAD(TEST_XDP_FRAME_SIZE - XDP_PACKET_HEADROOM) == TEST_MAX_PKT_SIZE"

[Alexander Lobakin <aleksander.lobakin@intel.com>]

From: Kernel Test Robot <lkp@intel.com>
Date: Fri, 17 Feb 2023 21:45:40 +0800

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   c068f40300a0eaa34f7105d137a5560b86951aa9
> commit: 6c20822fada1b8adb77fa450d03a0d449686a4a9 [12987/13499] bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES
> config: ia64-randconfig-r025-20230213 (https://download.01.org/0day-ci/archive/20230217/202302172104.q3ddwzqu-lkp@intel.com/config)
> compiler: ia64-linux-gcc (GCC) 12.1.0

ia64 has 128-byte cacheline on some configs. While I can easily test it
in the kernel, what do I do in the userspace test >_<
Or just exclude non-{64,256} CLs from the assertion?

> 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/next/linux-next.git/commit/?id=6c20822fada1b8adb77fa450d03a0d449686a4a9
>         git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>         git fetch --no-tags linux-next master
>         git checkout 6c20822fada1b8adb77fa450d03a0d449686a4a9
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 olddefconfig
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 SHELL=/bin/bash net/
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202302172104.q3ddwzqu-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from include/linux/container_of.h:5,
>                     from include/linux/list.h:5,
>                     from include/linux/timer.h:5,
>                     from include/linux/workqueue.h:9,
>                     from include/linux/bpf.h:10,
>                     from net/bpf/test_run.c:4:
>>> include/linux/build_bug.h:78:41: error: static assertion failed: "SKB_WITH_OVERHEAD(TEST_XDP_FRAME_SIZE - XDP_PACKET_HEADROOM) == TEST_MAX_PKT_SIZE"
>       78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
>          |                                         ^~~~~~~~~~~~~~
>    include/linux/build_bug.h:77:34: note: in expansion of macro '__static_assert'
>       77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
>          |                                  ^~~~~~~~~~~~~~~
>    net/bpf/test_run.c:132:1: note: in expansion of macro 'static_assert'
>      132 | static_assert(SKB_WITH_OVERHEAD(TEST_XDP_FRAME_SIZE - XDP_PACKET_HEADROOM) ==
>          | ^~~~~~~~~~~~~
> 
> 
> vim +78 include/linux/build_bug.h
> 
> bc6245e5efd70c Ian Abbott       2017-07-10  60  
> 6bab69c65013be Rasmus Villemoes 2019-03-07  61  /**
> 6bab69c65013be Rasmus Villemoes 2019-03-07  62   * static_assert - check integer constant expression at build time
> 6bab69c65013be Rasmus Villemoes 2019-03-07  63   *
> 6bab69c65013be Rasmus Villemoes 2019-03-07  64   * static_assert() is a wrapper for the C11 _Static_assert, with a
> 6bab69c65013be Rasmus Villemoes 2019-03-07  65   * little macro magic to make the message optional (defaulting to the
> 6bab69c65013be Rasmus Villemoes 2019-03-07  66   * stringification of the tested expression).
> 6bab69c65013be Rasmus Villemoes 2019-03-07  67   *
> 6bab69c65013be Rasmus Villemoes 2019-03-07  68   * Contrary to BUILD_BUG_ON(), static_assert() can be used at global
> 6bab69c65013be Rasmus Villemoes 2019-03-07  69   * scope, but requires the expression to be an integer constant
> 6bab69c65013be Rasmus Villemoes 2019-03-07  70   * expression (i.e., it is not enough that __builtin_constant_p() is
> 6bab69c65013be Rasmus Villemoes 2019-03-07  71   * true for expr).
> 6bab69c65013be Rasmus Villemoes 2019-03-07  72   *
> 6bab69c65013be Rasmus Villemoes 2019-03-07  73   * Also note that BUILD_BUG_ON() fails the build if the condition is
> 6bab69c65013be Rasmus Villemoes 2019-03-07  74   * true, while static_assert() fails the build if the expression is
> 6bab69c65013be Rasmus Villemoes 2019-03-07  75   * false.
> 6bab69c65013be Rasmus Villemoes 2019-03-07  76   */
> 6bab69c65013be Rasmus Villemoes 2019-03-07  77  #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
> 6bab69c65013be Rasmus Villemoes 2019-03-07 @78  #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
> 6bab69c65013be Rasmus Villemoes 2019-03-07  79  
> 07a368b3f55a79 Maxim Levitsky   2022-10-25  80  
> 
> :::::: The code at line 78 was first introduced by commit
> :::::: 6bab69c65013bed5fce9f101a64a84d0385b3946 build_bug.h: add wrapper for _Static_assert
> 
> :::::: TO: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> :::::: CC: Linus Torvalds <torvalds@linux-foundation.org>
> 

Thanks,
Olek