scsi: libcxgbi: add check for valid cxgbi_task_data

In error case it is possible that ->cleanup_task() gets called without
calling ->alloc_pdu() in this case cxgbi_task_data is not valid, so add
a check for for valid cxgbi_task_data in cxgbi_cleanup_task().
Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/cxgbi/libcxgbi.c

@@ -2128,6 +2128,13 @@ void cxgbi_cleanup_task(struct iscsi_task *task)
 	struct iscsi_tcp_task *tcp_task = task->dd_data;
 	struct cxgbi_task_data *tdata = iscsi_task_cxgbi_data(task);
 
+	if (!tcp_task || !tdata || (tcp_task->dd_data != tdata)) {
+		pr_info("task 0x%p,0x%p, tcp_task 0x%p, tdata 0x%p/0x%p.\n",
+			task, task->sc, tcp_task,
+			tcp_task ? tcp_task->dd_data : NULL, tdata);
+		return;
+	}
+
 	log_debug(1 << CXGBI_DBG_ISCSI,
 		"task 0x%p, skb 0x%p, itt 0x%x.\n",
 		task, tdata->skb, task->hdr_itt);