Re: [PATCH v5 1/3] ARC: Emulate two-byte cmpxchg
From: kernel test robot
Date: Tue Oct 06 2026 - 05:58:05 EST
Hi Bradley,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on vgupta-arc/for-curr jcmvbkbc-xtensa/xtensa-for-next linus/master v7.3-rc6 next-20261005]
[cannot apply to vgupta-arc/for-next]
[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#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Bradley-Morgan/ARC-Emulate-two-byte-cmpxchg/20261005-120658
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20261005120700.383058-2-brads%40mainlining.org
patch subject: [PATCH v5 1/3] ARC: Emulate two-byte cmpxchg
config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20261006/202610061706.jjwf7ggl-lkp@xxxxxxxxx/config)
compiler: arc-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261006/202610061706.jjwf7ggl-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610061706.jjwf7ggl-lkp@xxxxxxxxx/
All errors (new ones prefixed by >>):
In file included from arch/arc/include/asm/atomic.h:13,
from include/linux/atomic.h:7,
from include/asm-generic/bitops/lock.h:5,
from arch/arc/include/asm/bitops.h:190,
from include/linux/bitops.h:67,
from include/linux/log2.h:12,
from kernel/bounds.c:14:
include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg':
>> arch/arc/include/asm/cmpxchg.h:54:46: error: implicit declaration of function 'cmpxchg_emu_u16'; did you mean 'cmpxchg_emu_u8'? [-Wimplicit-function-declaration]
54 | _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u16((volatile u16 *__force)_p_, (unsigned long)_o_, (unsigned long)_n_); \
| ^~~~~~~~~~~~~~~
include/linux/atomic.h:73:16: note: in expansion of macro 'arch_cmpxchg_relaxed'
73 | typeof(op##_relaxed(args)) __ret; \
| ^~
include/linux/atomic/atomic-arch-fallback.h:58:9: note: in expansion of macro '__atomic_op_fence'
58 | __atomic_op_fence(arch_cmpxchg, __VA_ARGS__)
| ^~~~~~~~~~~~~~~~~
include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
2026 | return raw_cmpxchg(&v->counter, old, new);
| ^~~~~~~~~~~
make[3]: *** [scripts/Makefile.build:185: kernel/bounds.s] Error 1
make[3]: Target 'prepare' not remade because of errors.
make[2]: *** [Makefile:1405: prepare0] Error 2
make[2]: Target 'prepare' not remade because of errors.
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:248: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +54 arch/arc/include/asm/cmpxchg.h
41
42 #define arch_cmpxchg_relaxed(ptr, old, new) \
43 ({ \
44 __typeof__(ptr) _p_ = (ptr); \
45 __typeof__(*(ptr)) _o_ = (old); \
46 __typeof__(*(ptr)) _n_ = (new); \
47 __typeof__(*(ptr)) _prev_; \
48 \
49 switch (sizeof(*(_p_))) { \
50 case 1: \
51 _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *__force)_p_, (uintptr_t)_o_, (uintptr_t)_n_); \
52 break; \
53 case 2: \
> 54 _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u16((volatile u16 *__force)_p_, (unsigned long)_o_, (unsigned long)_n_); \
55 break; \
56 case 4: \
57 _prev_ = __cmpxchg(_p_, _o_, _n_); \
58 break; \
59 default: \
60 BUILD_BUG(); \
61 } \
62 _prev_; \
63 })
64
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