Re: [paulmckrcu:cmpxchg2.2026.09.22a 25/28] arch/arc/include/asm/cmpxchg.h:71:23: warning: unused variable '_new_'
Bradley Morgan
brads at mainlining.org
Wed Sep 23 14:13:37 PDT 2026
On 23 September 2026 22:12:09 BST, kernel test robot <lkp at intel.com> wrote:
>tree: https://github.com/paulmckrcu/linux cmpxchg2.2026.09.22a
>head: 54c282c15475ebfae4712fe3ab637c9d19c723d6
>commit: b6d4f6af38f85e7948fd64f9bf09cbb858b4dade [25/28] ARC: Emulate two-byte cmpxchg
>config: arc-randconfig-1001-20260924 (https://download.01.org/0day-ci/archive/20260924/202609240539.AkulvjVe-lkp@intel.com/config)
>compiler: arc-linux-gcc (GCC) 14.3.0
>reproduce (this is a W=1 build):
>(https://download.01.org/0day-ci/archive/20260924/202609240539.AkulvjVe-lkp@intel.com/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 at intel.com>
>| Closes:
>https://lore.kernel.org/oe-kbuild-all/202609240539.AkulvjVe-lkp@intel.com/
>
>All warnings (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:80:23: error: '_o_' undeclared (first use in this function); did you mean '_p_'?
> 80 | if (_prev_ == _o_) \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
> 55 | #define raw_cmpxchg arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
> 2026 | return raw_cmpxchg(&v->counter, old, new);
> | ^~~~~~~~~~~
> arch/arc/include/asm/cmpxchg.h:80:23: note: each undeclared identifier is reported only once for each function it appears in
> 80 | if (_prev_ == _o_) \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
> 55 | #define raw_cmpxchg arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
> 2026 | return raw_cmpxchg(&v->counter, old, new);
> | ^~~~~~~~~~~
> arch/arc/include/asm/cmpxchg.h:81:24: error: '_n_' undeclared (first use in this function); did you mean '_p_'?
> 81 | *_p_ = _n_; \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
> 55 | #define raw_cmpxchg arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
> 2026 | return raw_cmpxchg(&v->counter, old, new);
> | ^~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:71:23: warning: unused variable '_new_'
>[-Wunused-variable]
> 71 | unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
> 55 | #define raw_cmpxchg arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
> 2026 | return raw_cmpxchg(&v->counter, old, new);
> | ^~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:70:23: warning: unused variable '_old_'
>[-Wunused-variable]
> 70 | unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
> 55 | #define raw_cmpxchg arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
> 2026 | return raw_cmpxchg(&v->counter, old, new);
> | ^~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg_acquire':
> arch/arc/include/asm/cmpxchg.h:80:23: error: '_o_' undeclared (first use in this function); did you mean '_p_'?
> 80 | if (_prev_ == _o_) \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:70:29: note: in expansion of macro 'arch_cmpxchg'
> 70 | #define raw_cmpxchg_acquire arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2055:16: note: in expansion of macro 'raw_cmpxchg_acquire'
> 2055 | return raw_cmpxchg_acquire(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> arch/arc/include/asm/cmpxchg.h:81:24: error: '_n_' undeclared (first use in this function); did you mean '_p_'?
> 81 | *_p_ = _n_; \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:70:29: note: in expansion of macro 'arch_cmpxchg'
> 70 | #define raw_cmpxchg_acquire arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2055:16: note: in expansion of macro 'raw_cmpxchg_acquire'
> 2055 | return raw_cmpxchg_acquire(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:71:23: warning: unused variable '_new_'
>[-Wunused-variable]
> 71 | unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:70:29: note: in expansion of macro 'arch_cmpxchg'
> 70 | #define raw_cmpxchg_acquire arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2055:16: note: in expansion of macro 'raw_cmpxchg_acquire'
> 2055 | return raw_cmpxchg_acquire(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:70:23: warning: unused variable '_old_'
>[-Wunused-variable]
> 70 | unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:70:29: note: in expansion of macro 'arch_cmpxchg'
> 70 | #define raw_cmpxchg_acquire arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2055:16: note: in expansion of macro 'raw_cmpxchg_acquire'
> 2055 | return raw_cmpxchg_acquire(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg_release':
> arch/arc/include/asm/cmpxchg.h:80:23: error: '_o_' undeclared (first use in this function); did you mean '_p_'?
> 80 | if (_prev_ == _o_) \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:82:29: note: in expansion of macro 'arch_cmpxchg'
> 82 | #define raw_cmpxchg_release arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2083:16: note: in expansion of macro 'raw_cmpxchg_release'
> 2083 | return raw_cmpxchg_release(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> arch/arc/include/asm/cmpxchg.h:81:24: error: '_n_' undeclared (first use in this function); did you mean '_p_'?
> 81 | *_p_ = _n_; \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:82:29: note: in expansion of macro 'arch_cmpxchg'
> 82 | #define raw_cmpxchg_release arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2083:16: note: in expansion of macro 'raw_cmpxchg_release'
> 2083 | return raw_cmpxchg_release(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:71:23: warning: unused variable '_new_'
>[-Wunused-variable]
> 71 | unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:82:29: note: in expansion of macro 'arch_cmpxchg'
> 82 | #define raw_cmpxchg_release arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2083:16: note: in expansion of macro 'raw_cmpxchg_release'
> 2083 | return raw_cmpxchg_release(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:70:23: warning: unused variable '_old_'
>[-Wunused-variable]
> 70 | unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:82:29: note: in expansion of macro 'arch_cmpxchg'
> 82 | #define raw_cmpxchg_release arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2083:16: note: in expansion of macro 'raw_cmpxchg_release'
> 2083 | return raw_cmpxchg_release(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg_relaxed':
> arch/arc/include/asm/cmpxchg.h:80:23: error: '_o_' undeclared (first use in this function); did you mean '_p_'?
> 80 | if (_prev_ == _o_) \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:91:29: note: in expansion of macro 'arch_cmpxchg'
> 91 | #define raw_cmpxchg_relaxed arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2108:16: note: in expansion of macro 'raw_cmpxchg_relaxed'
> 2108 | return raw_cmpxchg_relaxed(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> arch/arc/include/asm/cmpxchg.h:81:24: error: '_n_' undeclared (first use in this function); did you mean '_p_'?
> 81 | *_p_ = _n_; \
> | ^~~
> include/linux/atomic/atomic-arch-fallback.h:91:29: note: in expansion of macro 'arch_cmpxchg'
> 91 | #define raw_cmpxchg_relaxed arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2108:16: note: in expansion of macro 'raw_cmpxchg_relaxed'
> 2108 | return raw_cmpxchg_relaxed(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:71:23: warning: unused variable '_new_'
>[-Wunused-variable]
> 71 | unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:91:29: note: in expansion of macro 'arch_cmpxchg'
> 91 | #define raw_cmpxchg_relaxed arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2108:16: note: in expansion of macro 'raw_cmpxchg_relaxed'
> 2108 | return raw_cmpxchg_relaxed(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
>>> arch/arc/include/asm/cmpxchg.h:70:23: warning: unused variable '_old_'
>[-Wunused-variable]
> 70 | unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old)); \
> | ^~~~~
> include/linux/atomic/atomic-arch-fallback.h:91:29: note: in expansion of macro 'arch_cmpxchg'
> 91 | #define raw_cmpxchg_relaxed arch_cmpxchg
> | ^~~~~~~~~~~~
> include/linux/atomic/atomic-arch-fallback.h:2108:16: note: in expansion of macro 'raw_cmpxchg_relaxed'
> 2108 | return raw_cmpxchg_relaxed(&v->counter, old, new);
> | ^~~~~~~~~~~~~~~~~~~
> make[3]: *** [scripts/Makefile.build:185: kernel/bounds.s] Error 1 shuffle=1050985161
> make[3]: Target 'prepare' not remade because of errors.
> make[2]: *** [Makefile:1425: prepare0] Error 2 shuffle=1050985161
> make[2]: Target 'prepare' not remade because of errors.
> make[1]: *** [Makefile:248: __sub-make] Error 2 shuffle=1050985161
> make[1]: Target 'prepare' not remade because of errors.
> make: *** [Makefile:248: __sub-make] Error 2 shuffle=1050985161
> make: Target 'prepare' not remade because of errors.
>
>
>vim +/_new_ +71 arch/arc/include/asm/cmpxchg.h
>
> 66
> 67 #define arch_cmpxchg(ptr, old, new) \
> 68 ({ \
> 69 volatile __typeof__(ptr) _p_ = (ptr); \
> > 70 unsigned long _old_ = (unsigned long)(0 ? *(_p_) : (old)); \
> > 71 unsigned long _new_ = (unsigned long)(0 ? *(_p_) : (new)); \
> 72 __typeof__(*(ptr)) _prev_; \
> 73 unsigned long __flags; \
> 74 \
> 75 /* \
> 76 * spin lock/unlock provide the needed smp_mb() before/after \
> 77 */ \
> 78 atomic_ops_lock(__flags); \
> 79 _prev_ = *_p_; \
> 80 if (_prev_ == _o_) \
> 81 *_p_ = _n_; \
> 82 atomic_ops_unlock(__flags); \
> 83 _prev_; \
> 84 })
> 85
>
>--
>0-DAY CI Kernel Test Service
>https://github.com/intel/lkp-tests/wiki
Apparently nobody uses arc
--- Thanks!
"I'm not a very positive person" - Linus torvalds
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