mlx4_core: maintain available field in bitmap allocator

Add mlx4_bitmap_avail() to give the number of available resources. We want to
use this as a hint to whether to allocate a resources or not. This patch is
introduced to be used with allocation blue flame registers.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/mlx4/alloc.c

@@ -62,6 +62,9 @@ u32 mlx4_bitmap_alloc(struct mlx4_bitmap *bitmap)
 	} else
 		obj = -1;
 
+	if (obj != -1)
+		--bitmap->avail;
+
 	spin_unlock(&bitmap->lock);
 
 	return obj;
@@ -101,11 +104,19 @@ u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 	} else
 		obj = -1;
 
+	if (obj != -1)
+		bitmap->avail -= cnt;
+
 	spin_unlock(&bitmap->lock);
 
 	return obj;
 }
 
+u32 mlx4_bitmap_avail(struct mlx4_bitmap *bitmap)
+{
+	return bitmap->avail;
+}
+
 void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt)
 {
 	obj &= bitmap->max + bitmap->reserved_top - 1;
@@ -115,6 +126,7 @@ void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt)
 	bitmap->last = min(bitmap->last, obj);
 	bitmap->top = (bitmap->top + bitmap->max + bitmap->reserved_top)
 			& bitmap->mask;
+	bitmap->avail += cnt;
 	spin_unlock(&bitmap->lock);
 }
 
@@ -130,6 +142,7 @@ int mlx4_bitmap_init(struct mlx4_bitmap *bitmap, u32 num, u32 mask,
 	bitmap->max  = num - reserved_top;
 	bitmap->mask = mask;
 	bitmap->reserved_top = reserved_top;
+	bitmap->avail = num - reserved_top - reserved_bot;
 	spin_lock_init(&bitmap->lock);
 	bitmap->table = kzalloc(BITS_TO_LONGS(bitmap->max) *
 				sizeof (long), GFP_KERNEL);

drivers/net/mlx4/mlx4.h

@@ -105,6 +105,7 @@ struct mlx4_bitmap {
 	u32			max;
 	u32                     reserved_top;
 	u32			mask;
+	u32			avail;
 	spinlock_t		lock;
 	unsigned long	       *table;
 };
@@ -371,6 +372,7 @@ u32 mlx4_bitmap_alloc(struct mlx4_bitmap *bitmap);
 void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj);
 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 mlx4_bitmap_avail(struct mlx4_bitmap *bitmap);
 int mlx4_bitmap_init(struct mlx4_bitmap *bitmap, u32 num, u32 mask,
 		     u32 reserved_bot, u32 resetrved_top);
 void mlx4_bitmap_cleanup(struct mlx4_bitmap *bitmap);