linux-kernel - [PATCH v9 03/61] arm64: Turn flush_dcache_mmap

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Message-Id: <20180313132639.17387-4-willy@infradead.org>
Date:   Tue, 13 Mar 2018 06:25:41 -0700
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,
        Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
        linux-nilfs@...r.kernel.org
Subject: [PATCH v9 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 7dfcec4700fe..0094c6653b06 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -140,10 +140,8 @@ 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