IB/mlx5: Decrease memory consumption of mr caches

Change the logic so we do not allocate memory nor map the device
before actually posting to the REG_UMR QP. In addition, unmap and free
the memory after we get completion.
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/mlx5/mr.c

@@ -61,13 +61,11 @@ static int order2idx(struct mlx5_ib_dev *dev, int order)
 
 static int add_keys(struct mlx5_ib_dev *dev, int c, int num)
 {
-	struct device *ddev = dev->ib_dev.dma_device;
 	struct mlx5_mr_cache *cache = &dev->cache;
 	struct mlx5_cache_ent *ent = &cache->ent[c];
 	struct mlx5_create_mkey_mbox_in *in;
 	struct mlx5_ib_mr *mr;
 	int npages = 1 << ent->order;
-	int size = sizeof(u64) * npages;
 	int err = 0;
 	int i;
 
@@ -83,21 +81,6 @@ static int add_keys(struct mlx5_ib_dev *dev, int c, int num)
 		}
 		mr->order = ent->order;
 		mr->umred = 1;
-		mr->pas = kmalloc(size + 0x3f, GFP_KERNEL);
-		if (!mr->pas) {
-			kfree(mr);
-			err = -ENOMEM;
-			goto out;
-		}
-		mr->dma = dma_map_single(ddev, mr_align(mr->pas, 0x40), size,
-					 DMA_TO_DEVICE);
-		if (dma_mapping_error(ddev, mr->dma)) {
-			kfree(mr->pas);
-			kfree(mr);
-			err = -ENOMEM;
-			goto out;
-		}
-
 		in->seg.status = 1 << 6;
 		in->seg.xlt_oct_size = cpu_to_be32((npages + 1) / 2);
 		in->seg.qpn_mkey7_0 = cpu_to_be32(0xffffff << 8);
@@ -108,8 +91,6 @@ static int add_keys(struct mlx5_ib_dev *dev, int c, int num)
 					    sizeof(*in));
 		if (err) {
 			mlx5_ib_warn(dev, "create mkey failed %d\n", err);
-			dma_unmap_single(ddev, mr->dma, size, DMA_TO_DEVICE);
-			kfree(mr->pas);
 			kfree(mr);
 			goto out;
 		}
@@ -129,11 +110,9 @@ static int add_keys(struct mlx5_ib_dev *dev, int c, int num)
 
 static void remove_keys(struct mlx5_ib_dev *dev, int c, int num)
 {
-	struct device *ddev = dev->ib_dev.dma_device;
 	struct mlx5_mr_cache *cache = &dev->cache;
 	struct mlx5_cache_ent *ent = &cache->ent[c];
 	struct mlx5_ib_mr *mr;
-	int size;
 	int err;
 	int i;
 
@@ -149,15 +128,11 @@ static void remove_keys(struct mlx5_ib_dev *dev, int c, int num)
 		ent->size--;
 		spin_unlock(&ent->lock);
 		err = mlx5_core_destroy_mkey(&dev->mdev, &mr->mmr);
-		if (err) {
+		if (err)
 			mlx5_ib_warn(dev, "failed destroy mkey\n");
-		} else {
-			size = ALIGN(sizeof(u64) * (1 << mr->order), 0x40);
-			dma_unmap_single(ddev, mr->dma, size, DMA_TO_DEVICE);
-			kfree(mr->pas);
+		else
 			kfree(mr);
 	}
-	}
 }
 
 static ssize_t size_write(struct file *filp, const char __user *buf,
@@ -408,11 +383,9 @@ static void free_cached_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 
 static void clean_keys(struct mlx5_ib_dev *dev, int c)
 {
-	struct device *ddev = dev->ib_dev.dma_device;
 	struct mlx5_mr_cache *cache = &dev->cache;
 	struct mlx5_cache_ent *ent = &cache->ent[c];
 	struct mlx5_ib_mr *mr;
-	int size;
 	int err;
 
 	cancel_delayed_work(&ent->dwork);
@@ -428,15 +401,11 @@ static void clean_keys(struct mlx5_ib_dev *dev, int c)
 		ent->size--;
 		spin_unlock(&ent->lock);
 		err = mlx5_core_destroy_mkey(&dev->mdev, &mr->mmr);
-		if (err) {
+		if (err)
 			mlx5_ib_warn(dev, "failed destroy mkey\n");
-		} else {
-			size = ALIGN(sizeof(u64) * (1 << mr->order), 0x40);
-			dma_unmap_single(ddev, mr->dma, size, DMA_TO_DEVICE);
-			kfree(mr->pas);
+		else
 			kfree(mr);
 	}
-	}
 }
 
 static int mlx5_mr_cache_debugfs_init(struct mlx5_ib_dev *dev)
@@ -678,10 +647,12 @@ static struct mlx5_ib_mr *reg_umr(struct ib_pd *pd, struct ib_umem *umem,
 				  int page_shift, int order, int access_flags)
 {
 	struct mlx5_ib_dev *dev = to_mdev(pd->device);
+	struct device *ddev = dev->ib_dev.dma_device;
 	struct umr_common *umrc = &dev->umrc;
 	struct ib_send_wr wr, *bad;
 	struct mlx5_ib_mr *mr;
 	struct ib_sge sg;
+	int size = sizeof(u64) * npages;
 	int err;
 	int i;
 
@@ -700,6 +671,19 @@ static struct mlx5_ib_mr *reg_umr(struct ib_pd *pd, struct ib_umem *umem,
 	if (!mr)
 		return ERR_PTR(-EAGAIN);
 
+	mr->pas = kmalloc(size + 0x3f, GFP_KERNEL);
+	if (!mr->pas) {
+		err = -ENOMEM;
+		goto error;
+	}
+	mr->dma = dma_map_single(ddev, mr_align(mr->pas, 0x40), size,
+				 DMA_TO_DEVICE);
+	if (dma_mapping_error(ddev, mr->dma)) {
+		kfree(mr->pas);
+		err = -ENOMEM;
+		goto error;
+	}
+
 	mlx5_ib_populate_pas(dev, umem, page_shift, mr_align(mr->pas, 0x40), 1);
 
 	memset(&wr, 0, sizeof(wr));
@@ -721,6 +705,9 @@ static struct mlx5_ib_mr *reg_umr(struct ib_pd *pd, struct ib_umem *umem,
 	wait_for_completion(&mr->done);
 	up(&umrc->sem);
 
+	dma_unmap_single(ddev, mr->dma, size, DMA_TO_DEVICE);
+	kfree(mr->pas);
+
 	if (mr->status != IB_WC_SUCCESS) {
 		mlx5_ib_warn(dev, "reg umr failed\n");
 		err = -EFAULT;