Merge branch 'hwbm-locking-fixes'

Gregory CLEMENT says:

====================
Fix spinlock usage in HWBM

these two patches fix spinlock related issues introduced in v4.6. They
have been reported by Russell King and Jean-Jacques Hiblot.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvneta_bm.c

@@ -189,6 +189,7 @@ struct mvneta_bm_pool *mvneta_bm_pool_use(struct mvneta_bm *priv, u8 pool_id,
 			SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 		hwbm_pool->construct = mvneta_bm_construct;
 		hwbm_pool->priv = new_pool;
+		spin_lock_init(&hwbm_pool->lock);
 
 		/* Create new pool */
 		err = mvneta_bm_pool_create(priv, new_pool);

net/core/hwbm.c

@@ -55,18 +55,21 @@ int hwbm_pool_add(struct hwbm_pool *bm_pool, unsigned int buf_num, gfp_t gfp)
 	spin_lock_irqsave(&bm_pool->lock, flags);
 	if (bm_pool->buf_num == bm_pool->size) {
 		pr_warn("pool already filled\n");
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return bm_pool->buf_num;
 	}
 
 	if (buf_num + bm_pool->buf_num > bm_pool->size) {
 		pr_warn("cannot allocate %d buffers for pool\n",
 			buf_num);
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return 0;
 	}
 
 	if ((buf_num + bm_pool->buf_num) < bm_pool->buf_num) {
 		pr_warn("Adding %d buffers to the %d current buffers will overflow\n",
 			buf_num,  bm_pool->buf_num);
+		spin_unlock_irqrestore(&bm_pool->lock, flags);
 		return 0;
 	}