IB/iser: Use separate buffers for the login request/response

The driver counted on the transactional nature of iSCSI login/text
flows and used the same buffer for both the request and the response.
We also went further and did DMA mapping only once, with
DMA_FROM_DEVICE, which violates the DMA mapping API. Fix that by
using different buffers, one for requests and one for responses, and
use the correct DMA mapping direction for each.

Signed-off-by: Or Gerlitz <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/ulp/iser/iscsi_iser.h

···
 	struct list_head	     conn_list;       /* entry in ig conn list */
 
 	char  			     *login_buf;
-	u64 			     login_dma;
+	char			     *login_req_buf, *login_resp_buf;
+	u64			     login_req_dma, login_resp_dma;
 	unsigned int 		     rx_desc_head;
 	struct iser_rx_desc	     *rx_descs;
 	struct ib_recv_wr	     rx_wr[ISER_MIN_POSTED_RX];

drivers/infiniband/ulp/iser/iser_initiator.c

···
 	struct iser_device *device = ib_conn->device;
 
 	if (ib_conn->login_buf) {
-		ib_dma_unmap_single(device->ib_device, ib_conn->login_dma,
-			ISER_RX_LOGIN_SIZE, DMA_FROM_DEVICE);
+		if (ib_conn->login_req_dma)
+			ib_dma_unmap_single(device->ib_device,
+				ib_conn->login_req_dma,
+				ISCSI_DEF_MAX_RECV_SEG_LEN, DMA_TO_DEVICE);
+		if (ib_conn->login_resp_dma)
+			ib_dma_unmap_single(device->ib_device,
+				ib_conn->login_resp_dma,
+				ISER_RX_LOGIN_SIZE, DMA_FROM_DEVICE);
 		kfree(ib_conn->login_buf);
 	}
 
···
 	unsigned long data_seg_len;
 	int err = 0;
 	struct iser_device *device;
+	struct iser_conn *ib_conn = iser_conn->ib_conn;
 
 	/* build the tx desc regd header and add it to the tx desc dto */
 	mdesc->type = ISCSI_TX_CONTROL;
···
 			iser_err("data present on non login task!!!\n");
 			goto send_control_error;
 		}
-		memcpy(iser_conn->ib_conn->login_buf, task->data,
+
+		ib_dma_sync_single_for_cpu(device->ib_device,
+			ib_conn->login_req_dma, task->data_count,
+			DMA_TO_DEVICE);
+
+		memcpy(iser_conn->ib_conn->login_req_buf, task->data,
 							task->data_count);
-		tx_dsg->addr    = iser_conn->ib_conn->login_dma;
+
+		ib_dma_sync_single_for_device(device->ib_device,
+			ib_conn->login_req_dma, task->data_count,
+			DMA_TO_DEVICE);
+
+		tx_dsg->addr    = iser_conn->ib_conn->login_req_dma;
 		tx_dsg->length  = task->data_count;
 		tx_dsg->lkey    = device->mr->lkey;
 		mdesc->num_sge = 2;
···
 	int rx_buflen, outstanding, count, err;
 
 	/* differentiate between login to all other PDUs */
-	if ((char *)rx_desc == ib_conn->login_buf) {
-		rx_dma = ib_conn->login_dma;
+	if ((char *)rx_desc == ib_conn->login_resp_buf) {
+		rx_dma = ib_conn->login_resp_dma;
 		rx_buflen = ISER_RX_LOGIN_SIZE;
 	} else {
 		rx_dma = rx_desc->dma_addr;
···
 	 * for the posted rx bufs refcount to become zero handles everything   */
 	conn->ib_conn->post_recv_buf_count--;
 
-	if (rx_dma == ib_conn->login_dma)
+	if (rx_dma == ib_conn->login_resp_dma)
 		return;
 
 	outstanding = ib_conn->post_recv_buf_count;

drivers/infiniband/ulp/iser/iser_verbs.c

···
 {
 	struct iser_device	*device;
 	struct ib_qp_init_attr	init_attr;
-	int			ret = -ENOMEM;
+	int			req_err, resp_err, ret = -ENOMEM;
 	struct ib_fmr_pool_param params;
 
 	BUG_ON(ib_conn->device == NULL);
 
 	device = ib_conn->device;
 
-	ib_conn->login_buf = kmalloc(ISER_RX_LOGIN_SIZE, GFP_KERNEL);
+	ib_conn->login_buf = kmalloc(ISCSI_DEF_MAX_RECV_SEG_LEN +
+					ISER_RX_LOGIN_SIZE, GFP_KERNEL);
 	if (!ib_conn->login_buf)
 		goto out_err;
 
-	ib_conn->login_dma = ib_dma_map_single(ib_conn->device->ib_device,
-				(void *)ib_conn->login_buf, ISER_RX_LOGIN_SIZE,
-				DMA_FROM_DEVICE);
+	ib_conn->login_req_buf  = ib_conn->login_buf;
+	ib_conn->login_resp_buf = ib_conn->login_buf + ISCSI_DEF_MAX_RECV_SEG_LEN;
+
+	ib_conn->login_req_dma = ib_dma_map_single(ib_conn->device->ib_device,
+				(void *)ib_conn->login_req_buf,
+				ISCSI_DEF_MAX_RECV_SEG_LEN, DMA_TO_DEVICE);
+
+	ib_conn->login_resp_dma = ib_dma_map_single(ib_conn->device->ib_device,
+				(void *)ib_conn->login_resp_buf,
+				ISER_RX_LOGIN_SIZE, DMA_FROM_DEVICE);
+
+	req_err  = ib_dma_mapping_error(device->ib_device, ib_conn->login_req_dma);
+	resp_err = ib_dma_mapping_error(device->ib_device, ib_conn->login_resp_dma);
+
+	if (req_err || resp_err) {
+		if (req_err)
+			ib_conn->login_req_dma = 0;
+		if (resp_err)
+			ib_conn->login_resp_dma = 0;
+		goto out_err;
+	}
 
 	ib_conn->page_vec = kmalloc(sizeof(struct iser_page_vec) +
 				    (sizeof(u64) * (ISCSI_ISER_SG_TABLESIZE +1)),
···
 	struct ib_sge	  sge;
 	int ib_ret;
 
-	sge.addr   = ib_conn->login_dma;
+	sge.addr   = ib_conn->login_resp_dma;
 	sge.length = ISER_RX_LOGIN_SIZE;
 	sge.lkey   = ib_conn->device->mr->lkey;
 
-	rx_wr.wr_id   = (unsigned long)ib_conn->login_buf;
+	rx_wr.wr_id   = (unsigned long)ib_conn->login_resp_buf;
 	rx_wr.sg_list = &sge;
 	rx_wr.num_sge = 1;
 	rx_wr.next    = NULL;