[PATCH net v2] net: ethernet: mtk_eth_soc: Reset prog ptr to old_prog in case of error in mtk_xdp_setup()

[Lorenzo Bianconi]

Reset eBPF program pointer to old_prog and do not decrease its ref-count
if mtk_open routine in mtk_xdp_setup() fails.

Fixes: 7c26c20da5d42 ("net: ethernet: mtk_eth_soc: add basic XDP support")
Suggested-by: Paolo Valerio <pvalerio at redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
Changes in v2:
- Reset prog_ptr to old_prog instead of always setting it to NULL
- Link to v1: https://lore.kernel.org/r/20260227-mtk-xdp-prog-ptr-fix-v1-1-b73d7588b645@kernel.org
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 1060764b9f17da251a1437c4e0fb7042d14307a8..bb8ced22ca3be239ae268f042efc119c96285947 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -3770,12 +3770,21 @@ static int mtk_xdp_setup(struct net_device *dev, struct bpf_prog *prog,
 		mtk_stop(dev);
 
 	old_prog = rcu_replace_pointer(eth->prog, prog, lockdep_rtnl_is_held());
+
+	if (netif_running(dev) && need_update) {
+		int err;
+
+		err = mtk_open(dev);
+		if (err) {
+			rcu_assign_pointer(eth->prog, old_prog);
+
+			return err;
+		}
+	}
+
 	if (old_prog)
 		bpf_prog_put(old_prog);
 
-	if (netif_running(dev) && need_update)
-		return mtk_open(dev);
-
 	return 0;
 }
 

---
base-commit: c69855ada28656fdd7e197b6e24cd40a04fe14d3
change-id: 20260227-mtk-xdp-prog-ptr-fix-af59b9cce7ba

Best regards,
-- 
Lorenzo Bianconi <lorenzo at kernel.org>