Re: [PATCH net-next] net: dlink: count dropped packets on skb allocation failure

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 12 Sep 2025 19:03:46 +0900 Yeounsu Moon wrote:
> > I'm not sure that failing to allocate a buffer results in dropping
> > one packet in this driver. The statistics have specific meaning, if
> > you're just trying to use dropped to mean "buffer allocation failures"
> > that's not allowed. If I'm misreading the code please explain in more
> > detail in the commit message and repost.
> 
> I think you understand the code better than I do.
> Your insights are always surprising to me.
> 
> I believed that when `netdev_alloc_skb()` fails, it leads to dropping packets.
> I also found many cases where `rx_dropped` was incremented when
> `netdev_alloc_skb()` failed.
> 
> However, I'm not entirely sure whether such a failure actually results
> in a misisng packet. I'll resend the patch after verifying whether the packet
> is really dropped.

There's a ring of outstanding Rx buffers. If the ring becomes
completely empty we'll start dropping. But that's not the same
as one allocation failure == one packet drop.