[PATCH] mlx4: use bitmap library

[PATCH] mlx4: use bitmap library

[Akinobu Mita]

Use bitmap_set() and bitmap_clear()

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
---
 drivers/net/mlx4/alloc.c |   15 ++++-----------
 1 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/net/mlx4/alloc.c b/drivers/net/mlx4/alloc.c
index 8c85156..76595bd 100644
--- a/drivers/net/mlx4/alloc.c
+++ b/drivers/net/mlx4/alloc.c
@@ -74,7 +74,7 @@ void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj)
 
 u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 {
-	u32 obj, i;
+	u32 obj;
 
 	if (likely(cnt == 1 && align == 1))
 		return mlx4_bitmap_alloc(bitmap);
@@ -91,8 +91,7 @@ u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 	}
 
 	if (obj < bitmap->max) {
-		for (i = 0; i < cnt; i++)
-			set_bit(obj + i, bitmap->table);
+		bitmap_set(bitmap->table, obj, cnt);
 		if (obj == bitmap->last) {
 			bitmap->last = (obj + cnt);
 			if (bitmap->last >= bitmap->max)
@@ -109,13 +108,10 @@ u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 
 void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt)
 {
-	u32 i;
-
 	obj &= bitmap->max + bitmap->reserved_top - 1;
 
 	spin_lock(&bitmap->lock);
-	for (i = 0; i < cnt; i++)
-		clear_bit(obj + i, bitmap->table);
+	bitmap_clear(bitmap->table, obj, cnt);
 	bitmap->last = min(bitmap->last, obj);
 	bitmap->top = (bitmap->top + bitmap->max + bitmap->reserved_top)
 			& bitmap->mask;
@@ -125,8 +121,6 @@ void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt)
 int mlx4_bitmap_init(struct mlx4_bitmap *bitmap, u32 num, u32 mask,
 		     u32 reserved_bot, u32 reserved_top)
 {
-	int i;
-
 	/* num must be a power of 2 */
 	if (num != roundup_pow_of_two(num))
 		return -EINVAL;
@@ -142,8 +136,7 @@ int mlx4_bitmap_init(struct mlx4_bitmap *bitmap, u32 num, u32 mask,
 	if (!bitmap->table)
 		return -ENOMEM;
 
-	for (i = 0; i < reserved_bot; ++i)
-		set_bit(i, bitmap->table);
+	bitmap_set(bitmap->table, 0, reserved_bot);
 
 	return 0;
 }
-- 
1.6.0.6

Re: [PATCH] mlx4: use bitmap library

[David Miller]

From: Akinobu Mita <akinobu.mita@gmail.com>
Date: Sat, 21 Aug 2010 18:24:48 +0900

> Use bitmap_set() and bitmap_clear()
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

Unlike loops calling set_bit() and clear_bit(), bitmap_set() and
bitmap_clear() are not atomic.

Are you sure this is ok here?

Re: [PATCH] mlx4: use bitmap library

[Akinobu Mita]

2010/8/23 David Miller <davem@davemloft.net>:
> From: Akinobu Mita <akinobu.mita@gmail.com>
> Date: Sat, 21 Aug 2010 18:24:48 +0900
>
>> Use bitmap_set() and bitmap_clear()
>>
>> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
>
> Unlike loops calling set_bit() and clear_bit(), bitmap_set() and
> bitmap_clear() are not atomic.
>
> Are you sure this is ok here?
>

I think this ok. Because the bitmap region is searched by
bitmap_find_next_zero_area() which cannot be atomic and
setting and clearing the bitmap region is protected by bitmap->lock
(except for initialization of the bitmap in mlx4_bitmap_init).

This change should be done when I submitted commit
43ff8b60853793fb0155b3e465739d2170c3aa2f ("mlx4: use
bitmap_find_next_zero_area")
at the same time.

I'll recheck this is ok and update the commit message for this change,
then resubmit the patch.

Re: [PATCH] mlx4: use bitmap library

[David Miller]

From: Akinobu Mita <akinobu.mita@gmail.com>
Date: Mon, 23 Aug 2010 13:21:55 +0900

> I'll recheck this is ok and update the commit message for this change,
> then resubmit the patch.

Ok, thank you.