linux-kernel - [PATCH] powerpc/64: Fix an out of date comment about MMIO ordering

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Date:   Thu, 16 Jul 2020 12:38:20 -0700
From:   Palmer Dabbelt <palmer@...belt.com>
To:     Will Deacon <willdeacon@...gle.com>
Cc:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        npiggin@...il.com, msuchanek@...e.de, tglx@...utronix.de,
        bigeasy@...utronix.de, jniethe5@...il.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com, Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH] powerpc/64: Fix an out of date comment about MMIO ordering

From: Palmer Dabbelt <palmerdabbelt@...gle.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).

Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.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
-- 
2.28.0.rc0.105.gf9edc3c819-goog