[android-common:android12-5.4 1/1] include/linux/kernel.h:843:43: warning: comparison of distinct pointer types lacks a cast

[kernel test robot <lkp@intel.com>]

tree:   https://android.googlesource.com/kernel/common android12-5.4
head:   14b655c6b6487670ee48bc9b760aefb4412b0f78
commit: f4b0174e9f18aaba59ee6ffdaf8827a7f94eb606 [1/1] tracing: Fix oob write in trace_seq_to_buffer()
config: i386-randconfig-2001-20250626 (https://download.01.org/0day-ci/archive/20250630/202506300640.42SWZMFf-lkp@intel.com/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/20250630/202506300640.42SWZMFf-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506300640.42SWZMFf-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/trace/trace.c:925:6: warning: no previous prototype for 'tracing_snapshot_instance_cond' [-Wmissing-prototypes]
     925 | void tracing_snapshot_instance_cond(struct trace_array *tr, void *cond_data)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from include/asm-generic/bug.h:19,
                    from arch/x86/include/asm/bug.h:83,
                    from include/linux/bug.h:5,
                    from include/linux/mmdebug.h:5,
                    from include/linux/mm.h:9,
                    from include/linux/ring_buffer.h:5,
                    from kernel/trace/trace.c:15:
   kernel/trace/trace.c: In function 'tracing_splice_read_pipe':
>> include/linux/kernel.h:843:43: warning: comparison of distinct pointer types lacks a cast
     843 |                 (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
         |                                           ^~
   include/linux/kernel.h:857:18: note: in expansion of macro '__typecheck'
     857 |                 (__typecheck(x, y) && __no_side_effects(x, y))
         |                  ^~~~~~~~~~~
   include/linux/kernel.h:867:31: note: in expansion of macro '__safe_cmp'
     867 |         __builtin_choose_expr(__safe_cmp(x, y), \
         |                               ^~~~~~~~~~
   include/linux/kernel.h:876:25: note: in expansion of macro '__careful_cmp'
     876 | #define min(x, y)       __careful_cmp(x, y, <)
         |                         ^~~~~~~~~~~~~
   kernel/trace/trace.c:6334:43: note: in expansion of macro 'min'
    6334 |                                           min((size_t)trace_seq_used(&iter->seq),
         |                                           ^~~
   kernel/trace/trace.c: At top level:
   kernel/trace/trace.c:8538:21: warning: no previous prototype for 'trace_array_create' [-Wmissing-prototypes]
    8538 | struct trace_array *trace_array_create(const char *name)
         |                     ^~~~~~~~~~~~~~~~~~
   kernel/trace/trace.c:8661:5: warning: no previous prototype for 'trace_array_destroy' [-Wmissing-prototypes]
    8661 | int trace_array_destroy(struct trace_array *this_tr)
         |     ^~~~~~~~~~~~~~~~~~~


vim +843 include/linux/kernel.h

526211bc58c4b3 Ingo Molnar    2009-03-05  829  
^1da177e4c3f41 Linus Torvalds 2005-04-16  830  /*
3c8ba0d61d04ce Kees Cook      2018-03-30  831   * min()/max()/clamp() macros must accomplish three things:
3c8ba0d61d04ce Kees Cook      2018-03-30  832   *
3c8ba0d61d04ce Kees Cook      2018-03-30  833   * - avoid multiple evaluations of the arguments (so side-effects like
3c8ba0d61d04ce Kees Cook      2018-03-30  834   *   "x++" happen only once) when non-constant.
3c8ba0d61d04ce Kees Cook      2018-03-30  835   * - perform strict type-checking (to generate warnings instead of
3c8ba0d61d04ce Kees Cook      2018-03-30  836   *   nasty runtime surprises). See the "unnecessary" pointer comparison
3c8ba0d61d04ce Kees Cook      2018-03-30  837   *   in __typecheck().
3c8ba0d61d04ce Kees Cook      2018-03-30  838   * - retain result as a constant expressions when called with only
3c8ba0d61d04ce Kees Cook      2018-03-30  839   *   constant expressions (to avoid tripping VLA warnings in stack
3c8ba0d61d04ce Kees Cook      2018-03-30  840   *   allocation usage).
3c8ba0d61d04ce Kees Cook      2018-03-30  841   */
3c8ba0d61d04ce Kees Cook      2018-03-30  842  #define __typecheck(x, y) \
3c8ba0d61d04ce Kees Cook      2018-03-30 @843  		(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
3c8ba0d61d04ce Kees Cook      2018-03-30  844  

:::::: The code at line 843 was first introduced by commit
:::::: 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 kernel.h: Retain constant expression output for max()/min()

:::::: TO: Kees Cook <keescook@chromium.org>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki