Re: [PATCH] locking/qspinlock: Ensure node is initialised before updating prev->next

[kbuild test robot]

Hi Will,

I love your patch! Yet something to improve:

[auto build test ERROR on v4.15]
[cannot apply to tip/locking/core tip/core/locking tip/auto-latest next-20180202]
[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/Will-Deacon/locking-qspinlock-Ensure-node-is-initialised-before-updating-prev-next/20180203-095222
config: x86_64-randconfig-x017-201804 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

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

   In file included from include/linux/kernel.h:10:0,
                    from include/linux/list.h:9,
                    from include/linux/smp.h:12,
                    from kernel/locking/qspinlock.c:25:
   kernel/locking/qspinlock.c: In function 'queued_spin_lock_slowpath':
>> include/linux/compiler.h:264:8: error: conversion to non-scalar type requested
     union { typeof(x) __val; char __c[1]; } __u = \
           ^
>> arch/x86/include/asm/barrier.h:71:2: note: in expansion of macro 'WRITE_ONCE'
     WRITE_ONCE(*p, v);      \
     ^~~~~~~~~~
   include/asm-generic/barrier.h:157:33: note: in expansion of macro '__smp_store_release'
    #define smp_store_release(p, v) __smp_store_release(p, v)
                                    ^~~~~~~~~~~~~~~~~~~
>> kernel/locking/qspinlock.c:419:3: note: in expansion of macro 'smp_store_release'
      smp_store_release(prev->next, node);
      ^~~~~~~~~~~~~~~~~
--
   In file included from include/linux/kernel.h:10:0,
                    from include/linux/list.h:9,
                    from include/linux/smp.h:12,
                    from kernel//locking/qspinlock.c:25:
   kernel//locking/qspinlock.c: In function 'queued_spin_lock_slowpath':
>> include/linux/compiler.h:264:8: error: conversion to non-scalar type requested
     union { typeof(x) __val; char __c[1]; } __u = \
           ^
>> arch/x86/include/asm/barrier.h:71:2: note: in expansion of macro 'WRITE_ONCE'
     WRITE_ONCE(*p, v);      \
     ^~~~~~~~~~
   include/asm-generic/barrier.h:157:33: note: in expansion of macro '__smp_store_release'
    #define smp_store_release(p, v) __smp_store_release(p, v)
                                    ^~~~~~~~~~~~~~~~~~~
   kernel//locking/qspinlock.c:419:3: note: in expansion of macro 'smp_store_release'
      smp_store_release(prev->next, node);
      ^~~~~~~~~~~~~~~~~

vim +/WRITE_ONCE +71 arch/x86/include/asm/barrier.h

47933ad4 Peter Zijlstra     2013-11-06  66  
1638fb72 Michael S. Tsirkin 2015-12-27  67  #define __smp_store_release(p, v)					\
47933ad4 Peter Zijlstra     2013-11-06  68  do {									\
47933ad4 Peter Zijlstra     2013-11-06  69  	compiletime_assert_atomic_type(*p);				\
47933ad4 Peter Zijlstra     2013-11-06  70  	barrier();							\
76695af2 Andrey Konovalov   2015-08-02 @71  	WRITE_ONCE(*p, v);						\
47933ad4 Peter Zijlstra     2013-11-06  72  } while (0)
47933ad4 Peter Zijlstra     2013-11-06  73  

:::::: The code at line 71 was first introduced by commit
:::::: 76695af20c015206cffb84b15912be6797d0cca2 locking, arch: use WRITE_ONCE()/READ_ONCE() in smp_store_release()/smp_load_acquire()

:::::: TO: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
:::::: CC: Ingo Molnar <mingo@xxxxxxxxxx>

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

Attachment: .config.gz
Description: application/gzip