linux-kernel - [PATCH v7 03/61] arm64: Turn flush_dcache_mmap

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Date:   Mon, 19 Feb 2018 11:44:58 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH v7 03/61] arm64: Turn flush_dcache_mmap_lock into a no-op

From: Matthew Wilcox <mawilcox@...rosoft.com>

ARM64 doesn't walk the VMA tree in its flush_dcache_page()
implementation, so has no need to take the tree_lock.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
Reviewed-by: Will Deacon <will.deacon@....com>
---
 arch/arm64/include/asm/cacheflush.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index bef9f418f089..550b0abea953 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -137,10 +137,8 @@ static inline void __flush_icache_all(void)
 	dsb(ish);
 }
 
-#define flush_dcache_mmap_lock(mapping) \
-	spin_lock_irq(&(mapping)->tree_lock)
-#define flush_dcache_mmap_unlock(mapping) \
-	spin_unlock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_lock(mapping)		do { } while (0)
+#define flush_dcache_mmap_unlock(mapping)	do { } while (0)
 
 /*
  * We don't appear to need to do anything here.  In fact, if we did, we'd
-- 
2.16.1