Hi Marco,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.4-rc6]
[cannot apply to next-20191106]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Marco-Elver/Add-Kernel-Concurrency-Sanitizer-KCSAN/20191105-002542
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a99d8080aaf358d5d23581244e5da23b35e340b9
config: x86_64-randconfig-a004-201944 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
--
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   fs/afs/dynroot.c: In function 'afs_dynroot_lookup':
   fs/afs/dynroot.c:117:6: warning: 'len' may be used uninitialized in this function [-Wmaybe-uninitialized]
     ret = lookup_one_len(name, dentry->d_parent, len);
         ^
   fs/afs/dynroot.c:91:6: note: 'len' was declared here
     int len;
         ^
--
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   7 real  2 user  5 sys  107.26% cpu 	make modules_prepare
--
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   In file included from include/linux/compiler_types.h:59:0,
                    from <command-line>:0:
>> include/linux/compiler_attributes.h:35:29: warning: "__GCC4_has_attribute___no_sanitize_thread__" is not defined [-Wundef]
    # define __has_attribute(x) __GCC4_has_attribute_##x
                                ^
>> include/linux/compiler-gcc.h:148:5: note: in expansion of macro '__has_attribute'
    #if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
        ^
   8 real  24 user  10 sys  405.87% cpu 	make prepare

vim +/__has_attribute +148 include/linux/compiler-gcc.h

   147	
 > 148	#if __has_attribute(__no_sanitize_thread__) && defined(__SANITIZE_THREAD__)
   149	#define __no_sanitize_thread                                                   \
   150		__attribute__((__noinline__)) __attribute__((no_sanitize_thread))
   151	#else
   152	#define __no_sanitize_thread
   153	#endif
   154	

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation