IB/iser: DMA unmap unaligned for RDMA data before touching it

iSER uses the DMA mapping api to map the page holding the
SCSI command data to the HCA DMA address space. When the
command data is not aligned for RDMA, the data is copied
to/from an allocated buffer which in turn is used for
executing this command. The pages associated with the
command must be unmapped before being touched.
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/iser/iscsi_iser.h

@@ -355,4 +355,11 @@ int  iser_post_send(struct iser_desc *tx_desc);
 
 int iser_conn_state_comp(struct iser_conn *ib_conn,
 			 enum iser_ib_conn_state comp);
+
+int iser_dma_map_task_data(struct iscsi_iser_cmd_task *iser_ctask,
+			    struct iser_data_buf       *data,
+			    enum   iser_data_dir       iser_dir,
+			    enum   dma_data_direction  dma_dir);
+
+void iser_dma_unmap_task_data(struct iscsi_iser_cmd_task *iser_ctask);
 #endif

drivers/infiniband/ulp/iser/iser_initiator.c

@@ -66,42 +66,6 @@ static void iser_dto_add_regd_buff(struct iser_dto *dto,
 	dto->regd_vector_len++;
 }
 
-static int iser_dma_map_task_data(struct iscsi_iser_cmd_task *iser_ctask,
-				  struct iser_data_buf       *data,
-				  enum   iser_data_dir       iser_dir,
-				  enum   dma_data_direction  dma_dir)
-{
-	struct device *dma_device;
-
-	iser_ctask->dir[iser_dir] = 1;
-	dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
-
-	data->dma_nents = dma_map_sg(dma_device, data->buf, data->size, dma_dir);
-	if (data->dma_nents == 0) {
-		iser_err("dma_map_sg failed!!!\n");
-		return -EINVAL;
-	}
-	return 0;
-}
-
-static void iser_dma_unmap_task_data(struct iscsi_iser_cmd_task *iser_ctask)
-{
-	struct device  *dma_device;
-	struct iser_data_buf *data;
-
-	dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
-
-	if (iser_ctask->dir[ISER_DIR_IN]) {
-		data = &iser_ctask->data[ISER_DIR_IN];
-		dma_unmap_sg(dma_device, data->buf, data->size, DMA_FROM_DEVICE);
-	}
-
-	if (iser_ctask->dir[ISER_DIR_OUT]) {
-		data = &iser_ctask->data[ISER_DIR_OUT];
-		dma_unmap_sg(dma_device, data->buf, data->size, DMA_TO_DEVICE);
-	}
-}
-
 /* Register user buffer memory and initialize passive rdma
  *  dto descriptor. Total data size is stored in
  *  iser_ctask->data[ISER_DIR_IN].data_len
@@ -699,14 +663,19 @@ void iser_ctask_rdma_init(struct iscsi_iser_cmd_task *iser_ctask)
 void iser_ctask_rdma_finalize(struct iscsi_iser_cmd_task *iser_ctask)
 {
 	int deferred;
+	int is_rdma_aligned = 1;
 
 	/* if we were reading, copy back to unaligned sglist,
 	 * anyway dma_unmap and free the copy
 	 */
-	if (iser_ctask->data_copy[ISER_DIR_IN].copy_buf != NULL)
+	if (iser_ctask->data_copy[ISER_DIR_IN].copy_buf != NULL) {
+		is_rdma_aligned = 0;
 		iser_finalize_rdma_unaligned_sg(iser_ctask, ISER_DIR_IN);
-	if (iser_ctask->data_copy[ISER_DIR_OUT].copy_buf != NULL)
+	}
+	if (iser_ctask->data_copy[ISER_DIR_OUT].copy_buf != NULL) {
+		is_rdma_aligned = 0;
 		iser_finalize_rdma_unaligned_sg(iser_ctask, ISER_DIR_OUT);
+	}
 
 	if (iser_ctask->dir[ISER_DIR_IN]) {
 		deferred = iser_regd_buff_release
@@ -726,7 +695,9 @@ void iser_ctask_rdma_finalize(struct iscsi_iser_cmd_task *iser_ctask)
 		}
 	}
 
-	iser_dma_unmap_task_data(iser_ctask);
+       /* if the data was unaligned, it was already unmapped and then copied */
+       if (is_rdma_aligned)
+		iser_dma_unmap_task_data(iser_ctask);
 }
 
 void iser_dto_buffs_release(struct iser_dto *dto)

drivers/infiniband/ulp/iser/iser_memory.c

@@ -369,6 +369,44 @@ static void iser_page_vec_build(struct iser_data_buf *data,
 	}
 }
 
+int iser_dma_map_task_data(struct iscsi_iser_cmd_task *iser_ctask,
+			    struct iser_data_buf       *data,
+			    enum   iser_data_dir       iser_dir,
+			    enum   dma_data_direction  dma_dir)
+{
+	struct device *dma_device;
+
+	iser_ctask->dir[iser_dir] = 1;
+	dma_device =
+		iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
+
+	data->dma_nents = dma_map_sg(dma_device, data->buf, data->size, dma_dir);
+	if (data->dma_nents == 0) {
+		iser_err("dma_map_sg failed!!!\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+void iser_dma_unmap_task_data(struct iscsi_iser_cmd_task *iser_ctask)
+{
+	struct device  *dma_device;
+	struct iser_data_buf *data;
+
+	dma_device =
+		iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
+
+	if (iser_ctask->dir[ISER_DIR_IN]) {
+		data = &iser_ctask->data[ISER_DIR_IN];
+		dma_unmap_sg(dma_device, data->buf, data->size, DMA_FROM_DEVICE);
+	}
+
+	if (iser_ctask->dir[ISER_DIR_OUT]) {
+		data = &iser_ctask->data[ISER_DIR_OUT];
+		dma_unmap_sg(dma_device, data->buf, data->size, DMA_TO_DEVICE);
+	}
+}
+
 /**
  * iser_reg_rdma_mem - Registers memory intended for RDMA,
  * obtaining rkey and va
@@ -394,6 +432,10 @@ int iser_reg_rdma_mem(struct iscsi_iser_cmd_task *iser_ctask,
 		iser_err("rdma alignment violation %d/%d aligned\n",
 			 aligned_len, mem->size);
 		iser_data_buf_dump(mem);
+
+		/* unmap the command data before accessing it */
+		iser_dma_unmap_task_data(iser_ctask);
+
 		/* allocate copy buf, if we are writing, copy the */
 		/* unaligned scatterlist, dma map the copy        */
 		if (iser_start_rdma_unaligned_sg(iser_ctask, cmd_dir) != 0)