Re: [PATCH] powerpc/64: Fix an out of date comment about MMIO ordering
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2020-07-16 23:09:45
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On Thu, 2020-07-16 at 12:38 -0700, Palmer Dabbelt wrote:
From: Palmer Dabbelt <redacted> 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.
quoted hunk ↗ jump to hunk
Signed-off-by: Palmer Dabbelt <redacted> --- 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