Messages in this thread | | | Subject | Re: [PATCH] powerpc/64: Fix an out of date comment about MMIO ordering | From | Benjamin Herrenschmidt <> | Date | Fri, 17 Jul 2020 08:38:29 +1000 |
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On Thu, 2020-07-16 at 12:38 -0700, Palmer Dabbelt wrote: > From: Palmer Dabbelt <palmerdabbelt@google.com> > > This primitive has been renamed, but because it was spelled incorrectly in the > first place it must have escaped the fixup patch. As far as I can tell this > logic is still correct: smp_mb__after_spinlock() uses the default smp_mb() > implementation, which is "sync" rather than "hwsync" but those are the same > (though I'm not that familiar with PowerPC).
Typo ? That must be me ... :)
Looks fine. Yes, sync and hwsync are the same (by opposition to lwsync which is lighter weight and doesn't order cache inhibited).
Cheers, Ben.
> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> > --- > arch/powerpc/kernel/entry_64.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index b3c9f15089b6..7b38b4daca93 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -357,7 +357,7 @@ _GLOBAL(_switch) > * kernel/sched/core.c). > * > * Uncacheable stores in the case of involuntary preemption must > - * be taken care of. The smp_mb__before_spin_lock() in __schedule() > + * be taken care of. The smp_mb__after_spinlock() in __schedule() > * is implemented as hwsync on powerpc, which orders MMIO too. So > * long as there is an hwsync in the context switch path, it will > * be executed on the source CPU after the task has performed
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