Thread (5 messages) 5 messages, 2 authors, 2026-01-13

Re: [PATCH net-next] net: dlink: count tx_dropped when dropping skb on link down

From: Yeounsu Moon <hidden>
Date: 2026-01-13 11:30:50
Also in: lkml

On Tue Jan 6, 2026 at 10:44 PM KST, Andrew Lunn wrote:
On Tue, Jan 06, 2026 at 09:23:51PM +0900, Yeounsu Moon wrote:
quoted
Increment tx_dropped when dropping the skb due to link down.

Tested-on: D-Link DGE-550T Rev-A3
Signed-off-by: Yeounsu Moon <redacted>
---
 drivers/net/ethernet/dlink/dl2k.c | 1 +
 1 file changed, 1 insertion(+)
diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index 846d58c769ea..edc6cd64ac56 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -733,6 +733,7 @@ start_xmit (struct sk_buff *skb, struct net_device *dev)
 	u64 tfc_vlan_tag = 0;
 
 	if (np->link_status == 0) {	/* Link Down */
+		dev->stats.tx_dropped++;
Do you see this being hit very often? It should be that as soon as you
know the link is down, you tell the core, and it will stop calling
start_xmit. If you see this counter being incremented a lot, it
indicates there is a problem somewhere else.

You might want to consider converting this driver to phylink.

	  Andrew
Sorry for the late reply. I recently started my first job and have been
a bit busy settling in.

To answer your question: this path is hit extremely rarely. In practice,
I only observed it in rather extreme cases, such as forcibly
disconnecting the physical link (e.g. unplugging the Ethernet cable). I
have not seen it occurring during normal operation.

Given that, dropping the packet in this situation seems reasonable, so I
added a counter to make such cases visible. However, I am not entirely
sure whether this is the right direction, or whether this is just
masking a problem that should be handled elsewhere.

Do you think this should instead be addressed by improving how link-down
is propagted to the core, or would converting this driver to phylink
help avoid or improve this situation?

    Yeounsu
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