RDMA/rw: Fix error flow during RDMA context initialization

In case the SGL was mapped for P2P DMA operation, we must unmap it using
pci_p2pdma_unmap_sg during the error unwind of rdma_rw_ctx_init()

Fixes: 7f73eac ("PCI/P2PDMA: Introduce pci_p2pdma_unmap_sg()")
Link: https://lore.kernel.org/r/20200220100819.41860-1-maxg@mellanox.com
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

Author: Max Gurtovoy

drivers/infiniband/core/rw.c

@@ -273,6 +273,23 @@ static int rdma_rw_init_single_wr(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
 	return 1;
 }
 
+static void rdma_rw_unmap_sg(struct ib_device *dev, struct scatterlist *sg,
+			     u32 sg_cnt, enum dma_data_direction dir)
+{
+	if (is_pci_p2pdma_page(sg_page(sg)))
+		pci_p2pdma_unmap_sg(dev->dma_device, sg, sg_cnt, dir);
+	else
+		ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
+}
+
+static int rdma_rw_map_sg(struct ib_device *dev, struct scatterlist *sg,
+			  u32 sg_cnt, enum dma_data_direction dir)
+{
+	if (is_pci_p2pdma_page(sg_page(sg)))
+		return pci_p2pdma_map_sg(dev->dma_device, sg, sg_cnt, dir);
+	return ib_dma_map_sg(dev, sg, sg_cnt, dir);
+}
+
 /**
  * rdma_rw_ctx_init - initialize a RDMA READ/WRITE context
  * @ctx:	context to initialize
@@ -295,11 +312,7 @@ int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 	struct ib_device *dev = qp->pd->device;
 	int ret;
 
-	if (is_pci_p2pdma_page(sg_page(sg)))
-		ret = pci_p2pdma_map_sg(dev->dma_device, sg, sg_cnt, dir);
-	else
-		ret = ib_dma_map_sg(dev, sg, sg_cnt, dir);
-
+	ret = rdma_rw_map_sg(dev, sg, sg_cnt, dir);
 	if (!ret)
 		return -ENOMEM;
 	sg_cnt = ret;
@@ -338,7 +351,7 @@ int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 	return ret;
 
 out_unmap_sg:
-	ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
+	rdma_rw_unmap_sg(dev, sg, sg_cnt, dir);
 	return ret;
 }
 EXPORT_SYMBOL(rdma_rw_ctx_init);
@@ -588,11 +601,7 @@ void rdma_rw_ctx_destroy(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 		break;
 	}
 
-	if (is_pci_p2pdma_page(sg_page(sg)))
-		pci_p2pdma_unmap_sg(qp->pd->device->dma_device, sg,
-				    sg_cnt, dir);
-	else
-		ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
+	rdma_rw_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
 }
 EXPORT_SYMBOL(rdma_rw_ctx_destroy);