> No, I don't mean to use the existing #ifdef/elif/else.
>
> Define an #ifdef /#else dedicated to xmb macros.
>
> Something like that:
>
> @@ -35,9 +35,15 @@
> * However, on CPUs that don't support lwsync, lwsync actually maps to a
> * heavy-weight sync, so smp_wmb() can be a lighter-weight eieio.
> */
> +#if defined(CONFIG_PPC64) || defined(CONFIG_PPC_E500MC)
> +#define __mb() asm volatile ("lwsync" : : : "memory")
> +#define __rmb() asm volatile ("lwsync" : : : "memory")
> +#define __wmb() asm volatile ("lwsync" : : : "memory")
> +#else
> #define __mb() __asm__ __volatile__ ("sync" : : : "memory")
> #define __rmb() __asm__ __volatile__ ("sync" : : : "memory")
> #define __wmb() __asm__ __volatile__ ("sync" : : : "memory")
> +#endif
Ok. Got it. Will do.
> >> Shouldn't you also consider the same for mb() ?
> > My change wasn't meant to address newer usages of as volatile
> > #defines. I just wanted to redefine the rmb and wmb #defines
> > to lwsync.
>
> That's my point, why not also redefine mb to lwsync ?
That would be incorrect. lwsync will only work for one: load or store.
mb() is meant for barriering both loads as well as stores so the sync
instruction is correct for that one.
>
> >>
> >> Note that your series will conflict with b6e259297a6b ("powerpc/kcsan:
> >> Memory barriers semantics") in powerpc/next tree.
> > I thought of defining the __rmb and __wmb macros but I decided against
> > it because I didn't understand kcsan completely.
> > I used the standard Linus' tree, not powerpc/next.
> > Can you tell me which branch or git repo I should make this patch on ?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git
>
> 'merge' branch is a merge of branches 'master', 'fixes' and 'next'.
>
> That's the branch to use, allthough it is not always in sync with fixes
> and next, in that case all you have to do is to locally merge 'next' and
> 'fixes' branch until it's done remotely.
>
> But just using 'next' branch also works most of the time.
>
> Note that 'next' branch should already be part of linux-next so you may
> also use linux-next if you prefer.
>
Will send another patch on this.
Thanks. Will use linux-next branch on this git repo.
