From: NeilBrown <neilb@suse.de>
Date: Mon, 19 Mar 2012 01:46:40 +0000 (+1100)
Subject: md/bitmap: remove some pointless locking.
X-Git-Tag: v3.4-rc1~147^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5a6c824ebb7c9f8dbbc92ffd3528e6366cad1a54;p=profile%2Fivi%2Fkernel-x86-ivi.git

md/bitmap: remove some pointless locking.

There is nothing gained by holding a lock while we check if a pointer
is NULL or not.  If there could be a race, then it could become NULL
immediately after the unlock - but there is no race here.

So just remove the locking.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index fcf3c94..e12b515 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -446,18 +446,13 @@ out:
 void bitmap_update_sb(struct bitmap *bitmap)
 {
 	bitmap_super_t *sb;
-	unsigned long flags;
 
 	if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
 		return;
 	if (bitmap->mddev->bitmap_info.external)
 		return;
-	spin_lock_irqsave(&bitmap->lock, flags);
-	if (!bitmap->sb_page) { /* no superblock */
-		spin_unlock_irqrestore(&bitmap->lock, flags);
+	if (!bitmap->sb_page) /* no superblock */
 		return;
-	}
-	spin_unlock_irqrestore(&bitmap->lock, flags);
 	sb = kmap_atomic(bitmap->sb_page, KM_USER0);
 	sb->events = cpu_to_le64(bitmap->mddev->events);
 	if (bitmap->mddev->events < bitmap->events_cleared)
@@ -683,15 +678,10 @@ static int bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
 			     enum bitmap_mask_op op)
 {
 	bitmap_super_t *sb;
-	unsigned long flags;
 	int old;
 
-	spin_lock_irqsave(&bitmap->lock, flags);
-	if (!bitmap->sb_page) { /* can't set the state */
-		spin_unlock_irqrestore(&bitmap->lock, flags);
+	if (!bitmap->sb_page) /* can't set the state */
 		return 0;
-	}
-	spin_unlock_irqrestore(&bitmap->lock, flags);
 	sb = kmap_atomic(bitmap->sb_page, KM_USER0);
 	old = le32_to_cpu(sb->state) & bits;
 	switch (op) {