[PATCH v2] eth: mlx4: Fix IS_ERR() vs NULL check bug in mlx4_en_create_rx_ring

[Miaoqian Lin <linmq006@gmail.com>]

Replace NULL check with IS_ERR() check after calling page_pool_create()
since this function returns error pointers (ERR_PTR).
Using NULL check could lead to invalid pointer dereference.

Fixes: 8533b14b3d65 ("eth: mlx4: create a page pool for Rx")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
----
Changes in v2:
use err = PTR_ERR(ring->pp);
v1 link: https://lore.kernel.org/all/20250805025057.3659898-1-linmq006@gmail.com
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 92a16ddb7d86..4728960c2c4e 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -267,8 +267,10 @@ int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv,
 	pp.dma_dir = priv->dma_dir;
 
 	ring->pp = page_pool_create(&pp);
-	if (!ring->pp)
+	if (!ring->pp) {
+		err = PTR_ERR(ring->pp);
 		goto err_ring;
+	}
 
 	if (xdp_rxq_info_reg(&ring->xdp_rxq, priv->dev, queue_index, 0) < 0)
 		goto err_pp;
-- 
2.39.5 (Apple Git-154)