On Tue, Jun 04, 2024 at 10:52:23PM +0200, Linus Walleij wrote: > Hi Paul, > > thanks for your patch! This caught my eye: > > On Tue, Jun 4, 2024 at 7:04 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > > Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems > > with ARCH < ARMv6K. > > ARCH == ARMv6. > > This ARCH < ARMv6K comes from inversion of the the a bit terse > comment for ifndef CONFIG_CPU_V6, which means "out of the > post-v6 CPUs, the following applies to those > V6". > > The code in the patch, IIUC make use of cmpxchg_emu_u8() > if and only if the CPU is V6. > > > -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ > > +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */ > > This is now a set with one member so this comment should say: > > /* ARCH == ARMv6 */ > > After this change. Thank you for looking this over! Does the following patch (to be merged into the original) capture it properly? Thanx, Paul ------------------------------------------------------------------------ diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index a428e06fe94ee..9beb64d305866 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -163,11 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */ +#ifdef CONFIG_CPU_V6 /* ARCH == ARMv6 */ case 1: oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); break; -#else /* min ARCH >= ARMv6K */ +#else /* min ARCH > ARMv6 */ case 1: do { asm volatile("@ __cmpxchg1\n"