| Message ID | 20231104091615.4884-2-wuqiang.matt@bytedance.com |
|---|---|
| State | New |
| Headers | show |
| Series | locking/atomic: arch_cmpxchg[64]_local undefined | expand |
On Sat, 4 Nov 2023 17:16:12 +0800 "wuqiang.matt" <wuqiang.matt@bytedance.com> wrote: > Macro __cmpxchg() renamed to __cmpxchg_32() to emphasize it's explicit > support of 32bit data size, BUILD_BUG_ON() added to avoid any possible > misuses with unsupported data types. > > In case CONFIG_ARC_HAS_LLSC is undefined, arch_cmpxchg() uses spinlock > to accomplish SMP-safety, so the BUILD_BUG_ON checking is uncecessary. > Looks good to me. Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com> > --- > arch/arc/include/asm/cmpxchg.h | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h > index e138fde067de..bf46514f6f12 100644 > --- a/arch/arc/include/asm/cmpxchg.h > +++ b/arch/arc/include/asm/cmpxchg.h > @@ -18,14 +18,16 @@ > * if (*ptr == @old) > * *ptr = @new > */ > -#define __cmpxchg(ptr, old, new) \ > +#define __cmpxchg_32(ptr, old, new) \ > ({ \ > __typeof__(*(ptr)) _prev; \ > \ > + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ > + \ > __asm__ __volatile__( \ > - "1: llock %0, [%1] \n" \ > + "1: llock %0, [%1] \n" \ > " brne %0, %2, 2f \n" \ > - " scond %3, [%1] \n" \ > + " scond %3, [%1] \n" \ > " bnz 1b \n" \ > "2: \n" \ > : "=&r"(_prev) /* Early clobber prevent reg reuse */ \ > @@ -47,7 +49,7 @@ > \ > switch(sizeof((_p_))) { \ > case 4: \ > - _prev_ = __cmpxchg(_p_, _o_, _n_); \ > + _prev_ = __cmpxchg_32(_p_, _o_, _n_); \ > break; \ > default: \ > BUILD_BUG(); \ > @@ -65,8 +67,6 @@ > __typeof__(*(ptr)) _prev_; \ > unsigned long __flags; \ > \ > - BUILD_BUG_ON(sizeof(_p_) != 4); \ > - \ > /* \ > * spin lock/unlock provide the needed smp_mb() before/after \ > */ \ > -- > 2.40.1 >
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h index e138fde067de..bf46514f6f12 100644 --- a/arch/arc/include/asm/cmpxchg.h +++ b/arch/arc/include/asm/cmpxchg.h @@ -18,14 +18,16 @@ * if (*ptr == @old) * *ptr = @new */ -#define __cmpxchg(ptr, old, new) \ +#define __cmpxchg_32(ptr, old, new) \ ({ \ __typeof__(*(ptr)) _prev; \ \ + BUILD_BUG_ON(sizeof(*(ptr)) != 4); \ + \ __asm__ __volatile__( \ - "1: llock %0, [%1] \n" \ + "1: llock %0, [%1] \n" \ " brne %0, %2, 2f \n" \ - " scond %3, [%1] \n" \ + " scond %3, [%1] \n" \ " bnz 1b \n" \ "2: \n" \ : "=&r"(_prev) /* Early clobber prevent reg reuse */ \ @@ -47,7 +49,7 @@ \ switch(sizeof((_p_))) { \ case 4: \ - _prev_ = __cmpxchg(_p_, _o_, _n_); \ + _prev_ = __cmpxchg_32(_p_, _o_, _n_); \ break; \ default: \ BUILD_BUG(); \ @@ -65,8 +67,6 @@ __typeof__(*(ptr)) _prev_; \ unsigned long __flags; \ \ - BUILD_BUG_ON(sizeof(_p_) != 4); \ - \ /* \ * spin lock/unlock provide the needed smp_mb() before/after \ */ \
Macro __cmpxchg() renamed to __cmpxchg_32() to emphasize it's explicit support of 32bit data size, BUILD_BUG_ON() added to avoid any possible misuses with unsupported data types. In case CONFIG_ARC_HAS_LLSC is undefined, arch_cmpxchg() uses spinlock to accomplish SMP-safety, so the BUILD_BUG_ON checking is uncecessary. Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com> --- arch/arc/include/asm/cmpxchg.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)