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

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Message-Id: <DCQQIQ5STYSJ.1X531TK8K9OTS@gmail.com>
Date: Fri, 12 Sep 2025 19:03:46 +0900
From: "Yeounsu Moon" <yyyynoom@...il.com>
To: "Jakub Kicinski" <kuba@...nel.org>
Cc: "Andrew Lunn" <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, "Eric Dumazet" <edumazet@...gle.com>, "Paolo Abeni"
 <pabeni@...hat.com>, <netdev@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: dlink: count dropped packets on skb
 allocation failure

On Fri Sep 12, 2025 at 9:08 AM KST, Jakub Kicinski wrote:
> On Wed, 10 Sep 2025 14:48:37 +0900 Yeounsu Moon wrote:
>> Track dropped packet statistics when skb allocation fails
>> in the receive path.
>
> 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.

Thank you for reviewing!

	Yeounsu Moon