[PATCH net-next v6 2/4] net: stmmac: clean up partially allocated DMA rings on error

[Ding Hui <dinghui1111@163.com>]

From: Ding Hui <dinghui@lixiang.com>

__alloc_dma_rx_desc_resources() and __alloc_dma_tx_desc_resources()
allocate resources in multiple steps but return early on failure
without cleaning up what they have already allocated. The outer
error paths then call the free helpers on partially-initialized
queues, relying on the NULL guards added previously.

Fix this by making each allocation function responsible for undoing
its own allocations on error, following the standard kernel error
handling pattern of cleaning up in reverse order of allocation.

Also free the RX resources in alloc_dma_desc_resources() when the TX
allocation fails, as the callers only free dma_conf itself on that
path.

Signed-off-by: Ding Hui <dinghui@lixiang.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 40 +++++++++++++++----
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 2f03600cc5bd..a8401b04d79f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2333,15 +2333,19 @@ 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;
@@ -2357,10 +2361,22 @@ 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:
+	dma_free_coherent(priv->device, size, addr, rx_q->dma_rx_phy);
+	rx_q->dma_erx = NULL;
+	rx_q->dma_rx = NULL;
+err_free_buf_pool:
+	kfree(rx_q->buf_pool);
+	rx_q->buf_pool = NULL;
+err_destroy_pool:
+	page_pool_destroy(rx_q->page_pool);
+	rx_q->page_pool = NULL;
+	return ret;
 }
 
 static int alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
@@ -2413,14 +2429,14 @@ static int __alloc_dma_tx_desc_resources(struct stmmac_priv *priv,
 
 	tx_q->tx_skbuff = kzalloc_objs(struct sk_buff *, dma_conf->dma_tx_size);
 	if (!tx_q->tx_skbuff)
-		return -ENOMEM;
+		goto err_free_skbuff_dma;
 
 	size = stmmac_get_tx_desc_size(priv, tx_q) * dma_conf->dma_tx_size;
 
 	addr = dma_alloc_coherent(priv->device, size,
 				  &tx_q->dma_tx_phy, GFP_KERNEL);
 	if (!addr)
-		return -ENOMEM;
+		goto err_free_skbuff;
 
 	if (priv->extend_desc)
 		tx_q->dma_etx = addr;
@@ -2430,6 +2446,14 @@ static int __alloc_dma_tx_desc_resources(struct stmmac_priv *priv,
 		tx_q->dma_tx = addr;
 
 	return 0;
+
+err_free_skbuff:
+	kfree(tx_q->tx_skbuff);
+	tx_q->tx_skbuff = NULL;
+err_free_skbuff_dma:
+	kfree(tx_q->tx_skbuff_dma);
+	tx_q->tx_skbuff_dma = NULL;
+	return -ENOMEM;
 }
 
 static int alloc_dma_tx_desc_resources(struct stmmac_priv *priv,
@@ -2472,6 +2496,8 @@ static int alloc_dma_desc_resources(struct stmmac_priv *priv,
 		return ret;
 
 	ret = alloc_dma_tx_desc_resources(priv, dma_conf);
+	if (ret)
+		free_dma_rx_desc_resources(priv, dma_conf);
 
 	return ret;
 }
-- 
2.34.1