Increment tx_dropped when dropping the skb due to link down.

Tested-on: D-Link DGE-550T Rev-A3
Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
---
 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++;
 		dev_kfree_skb_any(skb);
 		return NETDEV_TX_OK;
 	}
-- 
2.52.0

On Tue, Jan 06, 2026 at 09:23:51PM +0900, Yeounsu Moon wrote:
> Increment tx_dropped when dropping the skb due to link down.
> 
> Tested-on: D-Link DGE-550T Rev-A3
> Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
> ---
>  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

On Tue, Jan 6, 2026 at 10:44 PM Andrew Lunn <andrew@lunn.ch> wrote:
>
> You might want to consider converting this driver to phylink.
>
>           Andrew
One more note: I’ve started looking into phylink based on your suggestion,
and I appreciate you pointing me to that keyword.

It seems useful not only for this issue, but also for improving
the driver more generally.

Thanks for the pointer.

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:
>> Increment tx_dropped when dropping the skb due to link down.
>> 
>> Tested-on: D-Link DGE-550T Rev-A3
>> Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
>> ---
>>  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

On Tue, Jan 13, 2026 at 08:30:45PM +0900, Yeounsu Moon wrote:
> 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:
> >> Increment tx_dropped when dropping the skb due to link down.
> >> 
> >> Tested-on: D-Link DGE-550T Rev-A3
> >> Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
> >> ---
> >>  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.

In that case, i think this is fine. There is a race condition here
between indicating the carrier is down and the network stopping
passing packets, so this can happen, and incrementing the counter is
fine.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew