[PATCH net v2] net: natsemi: fix `rx_dropped` double accounting on `netif_rx()` failure

[PATCH net v2] net: natsemi: fix `rx_dropped` double accounting on `netif_rx()` failure

[Yeounsu Moon]

`netif_rx()` already increments `rx_dropped` core stat when it fails.
The driver was also updating `ndev->stats.rx_dropped` in the same path.
Since both are reported together via `ip -s -s` command, this resulted
in drops being counted twice in user-visible stats.

Keep the driver update on `if (unlikely(!skb))`, but skip it after
`netif_rx()` errors.

Fixes: caf586e5f23c ("net: add a core netdev->rx_dropped counter")
Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
---
changelog:
v1: https://lore.kernel.org/netdev/20250911053310.15966-2-yyyynoom@gmail.com/
v2:
- Correct commit reference in `Fixes:` tag.
- Fix incorrect commit message.
---
 drivers/net/ethernet/natsemi/ns83820.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
index 56d5464222d9..cdbf82affa7b 100644
--- a/drivers/net/ethernet/natsemi/ns83820.c
+++ b/drivers/net/ethernet/natsemi/ns83820.c
@@ -820,7 +820,7 @@ static void rx_irq(struct net_device *ndev)
 	struct ns83820 *dev = PRIV(ndev);
 	struct rx_info *info = &dev->rx_info;
 	unsigned next_rx;
-	int rx_rc, len;
+	int len;
 	u32 cmdsts;
 	__le32 *desc;
 	unsigned long flags;
@@ -881,8 +881,10 @@ static void rx_irq(struct net_device *ndev)
 		if (likely(CMDSTS_OK & cmdsts)) {
 #endif
 			skb_put(skb, len);
-			if (unlikely(!skb))
+			if (unlikely(!skb)) {
+				ndev->stats.rx_dropped++;
 				goto netdev_mangle_me_harder_failed;
+			}
 			if (cmdsts & CMDSTS_DEST_MULTI)
 				ndev->stats.multicast++;
 			ndev->stats.rx_packets++;
@@ -901,15 +903,12 @@ static void rx_irq(struct net_device *ndev)
 				__vlan_hwaccel_put_tag(skb, htons(ETH_P_IPV6), tag);
 			}
 #endif
-			rx_rc = netif_rx(skb);
-			if (NET_RX_DROP == rx_rc) {
-netdev_mangle_me_harder_failed:
-				ndev->stats.rx_dropped++;
-			}
+			netif_rx(skb);
 		} else {
 			dev_kfree_skb_irq(skb);
 		}
 
+netdev_mangle_me_harder_failed:
 		nr++;
 		next_rx = info->next_rx;
 		desc = info->descs + (DESC_SIZE * next_rx);
-- 
2.51.0

Re: [PATCH net v2] net: natsemi: fix `rx_dropped` double accounting on `netif_rx()` failure

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sat, 13 Sep 2025 15:01:36 +0900 you wrote:
> `netif_rx()` already increments `rx_dropped` core stat when it fails.
> The driver was also updating `ndev->stats.rx_dropped` in the same path.
> Since both are reported together via `ip -s -s` command, this resulted
> in drops being counted twice in user-visible stats.
> 
> Keep the driver update on `if (unlikely(!skb))`, but skip it after
> `netif_rx()` errors.
> 
> [...]

Here is the summary with links:
  - [net,v2] net: natsemi: fix `rx_dropped` double accounting on `netif_rx()` failure
    https://git.kernel.org/netdev/net/c/93ab4881a4e2

You are awesome, thank you!
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