linux-kernel - [PATCH 2/6] nommu: don't scan the vma list when deleting

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Date:	Mon, 28 Mar 2011 22:56:43 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Paul Mundt <lethal@...ux-sh.org>,
	David Howells <dhowells@...hat.com>,
	Greg Ungerer <gerg@...pgear.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/6] nommu: don't scan the vma list when deleting

Since the commit 297c5eee3724 ("mm: make the vma list be doubly linked")
made it a doubly linked list, we don't need to scan the list when
deleting @vma.

And the original code didn't update the prev pointer. Fix it too.

Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 mm/nommu.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index 20d9c330eb0e..a6a073f0745a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -770,7 +770,6 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
  */
 static void delete_vma_from_mm(struct vm_area_struct *vma)
 {
-	struct vm_area_struct **pp;
 	struct address_space *mapping;
 	struct mm_struct *mm = vma->vm_mm;
 
@@ -793,12 +792,14 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
 
 	/* remove from the MM's tree and list */
 	rb_erase(&vma->vm_rb, &mm->mm_rb);
-	for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
-		if (*pp == vma) {
-			*pp = vma->vm_next;
-			break;
-		}
-	}
+
+	if (vma->vm_prev)
+		vma->vm_prev->vm_next = vma->vm_next;
+	else
+		mm->mmap = vma->vm_next;
+
+	if (vma->vm_next)
+		vma->vm_next->vm_prev = vma->vm_prev;
 
 	vma->vm_mm = NULL;
 }
-- 
1.7.4

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