Re: [PATCH v5 3/3] locking/mutex: Ensure forward progress of waiter-spinner

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

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Hi Waiman,

[auto build test ERROR on tip/locking/core]
[also build test ERROR on v4.8-rc1]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Waiman-Long/locking-mutex-Enable-optimistic-spinning-of-lock-waiter/20160811-074736
config: arm-sunxi_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 5.4.0-6) 5.4.0 20160609
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm 

All error/warnings (new ones prefixed by >>):

   In file included from include/linux/compiler.h:58:0,
                    from include/uapi/linux/stddef.h:1,
                    from include/linux/stddef.h:4,
                    from include/uapi/linux/posix_types.h:4,
                    from include/uapi/linux/types.h:13,
                    from include/linux/types.h:5,
                    from include/linux/thread_info.h:10,
                    from include/asm-generic/current.h:4,
                    from ./arch/arm/include/generated/asm/current.h:1,
                    from include/linux/mutex.h:13,
                    from kernel/locking/mutex.c:20:
   kernel/locking/mutex.c: In function 'mutex_optimistic_spin':
>> include/linux/compiler-gcc.h:15:19: error: expected expression before '__asm__'
    #define barrier() __asm__ __volatile__("": : :"memory")
                      ^
>> arch/arm/include/asm/processor.h:82:23: note: in expansion of macro 'barrier'
    #define cpu_relax()   barrier()
                          ^
>> arch/arm/include/asm/processor.h:85:47: note: in expansion of macro 'cpu_relax'
    #define cpu_relax_lowlatency()                cpu_relax()
                                                  ^
>> kernel/locking/mutex.c:355:10: note: in expansion of macro 'cpu_relax_lowlatency'
     for (;; cpu_relax_lowlatency()) {
             ^

vim +/cpu_relax +85 arch/arm/include/asm/processor.h

^1da177e4 include/asm-arm/processor.h      Linus Torvalds  2005-04-16  76  
^1da177e4 include/asm-arm/processor.h      Linus Torvalds  2005-04-16  77  unsigned long get_wchan(struct task_struct *p);
^1da177e4 include/asm-arm/processor.h      Linus Torvalds  2005-04-16  78  
5dab26af1 arch/arm/include/asm/processor.h Will Deacon     2011-03-04  79  #if __LINUX_ARM_ARCH__ == 6 || defined(CONFIG_ARM_ERRATA_754327)
534be1d5a arch/arm/include/asm/processor.h Will Deacon     2010-06-21  80  #define cpu_relax()			smp_mb()
534be1d5a arch/arm/include/asm/processor.h Will Deacon     2010-06-21  81  #else
^1da177e4 include/asm-arm/processor.h      Linus Torvalds  2005-04-16 @82  #define cpu_relax()			barrier()
534be1d5a arch/arm/include/asm/processor.h Will Deacon     2010-06-21  83  #endif
^1da177e4 include/asm-arm/processor.h      Linus Torvalds  2005-04-16  84  
3a6bfbc91 arch/arm/include/asm/processor.h Davidlohr Bueso 2014-06-29 @85  #define cpu_relax_lowlatency()                cpu_relax()
3a6bfbc91 arch/arm/include/asm/processor.h Davidlohr Bueso 2014-06-29  86  
815d5ec86 include/asm-arm/processor.h      Al Viro         2006-01-12  87  #define task_pt_regs(p) \
32d39a935 include/asm-arm/processor.h      Al Viro         2006-01-12  88  	((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)

:::::: The code at line 85 was first introduced by commit
:::::: 3a6bfbc91df04b081a44d419e0260bad54abddf7 arch, locking: Ciao arch_mutex_cpu_relax()

:::::: TO: Davidlohr Bueso <davidlohr@hp.com>
:::::: CC: Ingo Molnar <mingo@kernel.org>

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0-DAY kernel test infrastructure                Open Source Technology Center
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