diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.c b/drivers/ntb/hw/amd/ntb_hw_amd.c
index 4940b6301d83..d687e8c2cc78 100644
--- a/drivers/ntb/hw/amd/ntb_hw_amd.c
+++ b/drivers/ntb/hw/amd/ntb_hw_amd.c
@@ -941,13 +941,10 @@ static void ndev_init_debugfs(struct amd_ntb_dev *ndev)
 		ndev->debugfs_dir =
 			debugfs_create_dir(pci_name(ndev->ntb.pdev),
 					   debugfs_dir);
-		if (IS_ERR(ndev->debugfs_dir))
-			ndev->debugfs_info = NULL;
-		else
-			ndev->debugfs_info =
-				debugfs_create_file("info", S_IRUSR,
-						    ndev->debugfs_dir, ndev,
-						    &amd_ntb_debugfs_info);
+		ndev->debugfs_info =
+			debugfs_create_file("info", S_IRUSR,
+					    ndev->debugfs_dir, ndev,
+					    &amd_ntb_debugfs_info);
 	}
 }
 
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 2abd2235bbca..f9e7847a378e 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -909,7 +909,7 @@ static int ntb_set_mw(struct ntb_transport_ctx *nt, int num_mw,
 	return 0;
 }
 
-static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
+static void ntb_qp_link_context_reset(struct ntb_transport_qp *qp)
 {
 	qp->link_is_up = false;
 	qp->active = false;
@@ -932,6 +932,13 @@ static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
 	qp->tx_async = 0;
 }
 
+static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
+{
+	ntb_qp_link_context_reset(qp);
+	if (qp->remote_rx_info)
+		qp->remote_rx_info->entry = qp->rx_max_entry - 1;
+}
+
 static void ntb_qp_link_cleanup(struct ntb_transport_qp *qp)
 {
 	struct ntb_transport_ctx *nt = qp->transport;
@@ -1174,7 +1181,7 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
 	qp->ndev = nt->ndev;
 	qp->client_ready = false;
 	qp->event_handler = NULL;
-	ntb_qp_link_down_reset(qp);
+	ntb_qp_link_context_reset(qp);
 
 	if (mw_num < qp_count % mw_count)
 		num_qps_mw = qp_count / mw_count + 1;
@@ -1894,7 +1901,7 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
 static int ntb_process_tx(struct ntb_transport_qp *qp,
 			  struct ntb_queue_entry *entry)
 {
-	if (qp->tx_index == qp->remote_rx_info->entry) {
+	if (!ntb_transport_tx_free_entry(qp)) {
 		qp->tx_ring_full++;
 		return -EAGAIN;
 	}
@@ -2276,9 +2283,13 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
 	struct ntb_queue_entry *entry;
 	int rc;
 
-	if (!qp || !qp->link_is_up || !len)
+	if (!qp || !len)
 		return -EINVAL;
 
+	/* If the qp link is down already, just ignore. */
+	if (!qp->link_is_up)
+		return 0;
+
 	entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
 	if (!entry) {
 		qp->tx_err_no_buf++;
@@ -2418,7 +2429,7 @@ unsigned int ntb_transport_tx_free_entry(struct ntb_transport_qp *qp)
 	unsigned int head = qp->tx_index;
 	unsigned int tail = qp->remote_rx_info->entry;
 
-	return tail > head ? tail - head : qp->tx_max_entry + tail - head;
+	return tail >= head ? tail - head : qp->tx_max_entry + tail - head;
 }
 EXPORT_SYMBOL_GPL(ntb_transport_tx_free_entry);
 
diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 65e1e5cf1b29..553f1f46bc66 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -1355,7 +1355,7 @@ static void perf_setup_dbgfs(struct perf_ctx *perf)
 	struct pci_dev *pdev = perf->ntb->pdev;
 
 	perf->dbgfs_dir = debugfs_create_dir(pci_name(pdev), perf_dbgfs_topdir);
-	if (!perf->dbgfs_dir) {
+	if (IS_ERR(perf->dbgfs_dir)) {
 		dev_warn(&perf->ntb->dev, "DebugFS unsupported\n");
 		return;
 	}
diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
index eeeb4b1c97d2..641cb7e05a47 100644
--- a/drivers/ntb/test/ntb_tool.c
+++ b/drivers/ntb/test/ntb_tool.c
@@ -370,16 +370,9 @@ static ssize_t tool_fn_write(struct tool_ctx *tc,
 	if (*offp)
 		return 0;
 
-	buf = kmalloc(size + 1, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, ubuf, size)) {
-		kfree(buf);
-		return -EFAULT;
-	}
-
-	buf[size] = 0;
+	buf = memdup_user_nul(ubuf, size);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
 
 	n = sscanf(buf, "%c %lli", &cmd, &bits);
 
@@ -1495,8 +1488,6 @@ static void tool_setup_dbgfs(struct tool_ctx *tc)
 
 	tc->dbgfs_dir = debugfs_create_dir(dev_name(&tc->ntb->dev),
 					   tool_dbgfs_topdir);
-	if (!tc->dbgfs_dir)
-		return;
 
 	debugfs_create_file("port", 0600, tc->dbgfs_dir,
 			    tc, &tool_port_fops);