Re:Re: [PATCH net-next v2] net: stmmac: fix error path cleanup in DMA descriptor ring allocation

Hi Lorenzo,

Thanks for your review comments.

At 2026-09-06 18:16:39, "Lorenzo Bianconi" [off-list ref] wrote:

quoted

From: Ding Hui <redacted>

Hi Ding Hui,

just a couple of nits inline.

Regards,
Lorenzo

[...]

quoted

 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 59 ++++++++++++++++---
 1 file changed, 50 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f2fc89176654..f0e06c011b8d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1728,7 +1728,7 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv,
 					 DMA_TO_DEVICE);
 	}
 

Is it more appropriate to move the tx_q->tx_skbuff_dma check here from
dma_free_tx_skbufs()?

tx_skbuff_dma is a per-queue resource, and stmmac_free_tx_buffer()
references it in multiple places across the function body. Moving the
NULL check into stmmac_free_tx_buffer() would require repeating it on
every call, introducing O(n) overhead proportional to dma_tx_size.
So I put it at the entry of dma_free_tx_skbufs().

quoted

-	if (tx_q->xdpf[i] &&
+	if (tx_q->xdpf && tx_q->xdpf[i] &&
 	    (tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_TX ||
 	     tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_NDO)) {
 		xdp_return_frame(tx_q->xdpf[i]);

@@ -1738,7 +1738,7 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv,
 	if (tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XSK_TX)
 		tx_q->xsk_frames_done++;
 
-	if (tx_q->tx_skbuff[i] &&
+	if (tx_q->tx_skbuff && tx_q->tx_skbuff[i] &&
 	    tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_SKB) {
 		dev_kfree_skb_any(tx_q->tx_skbuff[i]);
 		tx_q->tx_skbuff[i] = NULL;

@@ -1761,6 +1761,10 @@ static void dma_free_rx_skbufs(struct stmmac_priv *priv,
 	struct stmmac_rx_queue *rx_q = &dma_conf->rx_queue[queue];
 	int i;
 
+	/* buf_pool may not be allocated if alloc failed early */
+	if (!rx_q->buf_pool)
+		return;
+
 	for (i = 0; i < dma_conf->dma_rx_size; i++)
 		stmmac_free_rx_buffer(priv, rx_q, i);
 }

quoted

@@ -2272,15 +2284,19 @@ static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
 	}
 
 	rx_q->buf_pool = kzalloc_objs(*rx_q->buf_pool, dma_conf->dma_rx_size);
-	if (!rx_q->buf_pool)
-		return -ENOMEM;
+	if (!rx_q->buf_pool) {
+		ret = -ENOMEM;
+		goto err_destroy_pool;
+	}
 
 	size = stmmac_get_rx_desc_size(priv) * dma_conf->dma_rx_size;
 
 	addr = dma_alloc_coherent(priv->device, size, &rx_q->dma_rx_phy,
 				  GFP_KERNEL);
-	if (!addr)
-		return -ENOMEM;
+	if (!addr) {
+		ret = -ENOMEM;
+		goto err_free_buf_pool;
+	}
 
 	if (priv->extend_desc)
 		rx_q->dma_erx = addr;

@@ -2296,10 +2312,27 @@ static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
 	ret = xdp_rxq_info_reg(&rx_q->xdp_rxq, priv->dev, queue, napi_id);
 	if (ret) {
 		netdev_err(priv->dev, "Failed to register xdp rxq info\n");
-		return -EINVAL;
+		goto err_free_dma;
 	}
 
 	return 0;
+
+err_free_dma:
+	if (priv->extend_desc)
+		dma_free_coherent(priv->device, size, rx_q->dma_erx,
+				  rx_q->dma_rx_phy);
+	else
+		dma_free_coherent(priv->device, size, rx_q->dma_rx,
+				  rx_q->dma_rx_phy);

I guess you can use addr here and remove the if/else block

Excellent suggestion, will use addr directly in v3.

Thanks,
Ding Hui