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>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c
index d0b03f42658..0606744c3f8 100644
--- a/drivers/infiniband/ulp/iser/iser_memory.c
+++ b/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)