Hi Mark,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on powerpc/next linus/master tip/core/entry v5.13-rc6 next-20210616]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Mark-Rutland/thread_info-use-helpers-to-snapshot-thread-flags/20210616-183127
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: arm64-randconfig-p001-20210615 (attached as .config)
compiler: aarch64-linux-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://github.com/0day-ci/linux/commit/a1022e40673660308b0f52aa06bc5798d7575eba
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mark-Rutland/thread_info-use-helpers-to-snapshot-thread-flags/20210616-183127
        git checkout a1022e40673660308b0f52aa06bc5798d7575eba
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm64 

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

All errors (new ones prefixed by >>):

   arch/arm64/kernel/signal.c:927:17: warning: no previous prototype for 'do_notify_resume' [-Wmissing-prototypes]
     927 | asmlinkage void do_notify_resume(struct pt_regs *regs,
         |                 ^~~~~~~~~~~~~~~~
   arch/arm64/kernel/signal.c: In function 'do_notify_resume':
>> arch/arm64/kernel/signal.c:974:18: error: implicit declaration of function 'read_thead_flags'; did you mean 'read_thread_flags'? [-Werror=implicit-function-declaration]
     974 |   thread_flags = read_thead_flags();
         |                  ^~~~~~~~~~~~~~~~
         |                  read_thread_flags
   cc1: some warnings being treated as errors


vim +974 arch/arm64/kernel/signal.c

   926	
   927	asmlinkage void do_notify_resume(struct pt_regs *regs,
   928					 unsigned long thread_flags)
   929	{
   930		do {
   931			if (thread_flags & _TIF_NEED_RESCHED) {
   932				/* Unmask Debug and SError for the next task */
   933				local_daif_restore(DAIF_PROCCTX_NOIRQ);
   934	
   935				schedule();
   936			} else {
   937				local_daif_restore(DAIF_PROCCTX);
   938	
   939				if (thread_flags & _TIF_UPROBE)
   940					uprobe_notify_resume(regs);
   941	
   942				if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
   943					clear_thread_flag(TIF_MTE_ASYNC_FAULT);
   944					send_sig_fault(SIGSEGV, SEGV_MTEAERR,
   945						       (void __user *)NULL, current);
   946				}
   947	
   948				if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
   949					do_signal(regs);
   950	
   951				if (thread_flags & _TIF_NOTIFY_RESUME) {
   952					tracehook_notify_resume(regs);
   953					rseq_handle_notify_resume(NULL, regs);
   954	
   955					/*
   956					 * If we reschedule after checking the affinity
   957					 * then we must ensure that TIF_NOTIFY_RESUME
   958					 * is set so that we check the affinity again.
   959					 * Since tracehook_notify_resume() clears the
   960					 * flag, ensure that the compiler doesn't move
   961					 * it after the affinity check.
   962					 */
   963					barrier();
   964	
   965					if (cpu_affinity_invalid(regs))
   966						force_sig(SIGKILL);
   967				}
   968	
   969				if (thread_flags & _TIF_FOREIGN_FPSTATE)
   970					fpsimd_restore_current_state();
   971			}
   972	
   973			local_daif_mask();
 > 974			thread_flags = read_thead_flags();
   975		} while (thread_flags & _TIF_WORK_MASK);
   976	}
   977	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org