linux-kernel - [PATCH 07/12] rmap: wrap page_check_address() using __cond

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Date:	Thu, 30 Sep 2010 12:50:16 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 07/12] rmap: wrap page_check_address() using __cond_lock()

The page_check_address() conditionally grabs *@...p in case of returning
non-NULL. Rename and wrap it using __cond_lock() removes following
warnings from sparse:

 mm/rmap.c:472:9: warning: context imbalance in 'page_mapped_in_vma' - unexpected unlock
 mm/rmap.c:524:9: warning: context imbalance in 'page_referenced_one' - unexpected unlock
 mm/rmap.c:706:9: warning: context imbalance in 'page_mkclean_one' - unexpected unlock
 mm/rmap.c:1066:9: warning: context imbalance in 'try_to_unmap_one' - unexpected unlock

Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 include/linux/rmap.h |   13 ++++++++++++-
 mm/rmap.c            |    2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 0fa7769..490206c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -205,9 +205,20 @@ int try_to_unmap_one(struct page *, struct vm_area_struct *,
 /*
  * Called from mm/filemap_xip.c to unmap empty zero page
  */
-pte_t *page_check_address(struct page *, struct mm_struct *,
+pte_t *__page_check_address(struct page *, struct mm_struct *,
 				unsigned long, spinlock_t **, int);
 
+static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
+					unsigned long address,
+					spinlock_t **ptlp, int sync)
+{
+	pte_t *ptep;
+
+	__cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
+						       ptlp, sync));
+	return ptep;
+}
+
 /*
  * Used by swapoff to help locate where page is expected in vma.
  */
diff --git a/mm/rmap.c b/mm/rmap.c
index 244ff06..9c900dd 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -403,7 +403,7 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
  *
  * On success returns with pte mapped and locked.
  */
-pte_t *page_check_address(struct page *page, struct mm_struct *mm,
+pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
 			  unsigned long address, spinlock_t **ptlp, int sync)
 {
 	pgd_t *pgd;
-- 
1.7.2.2

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