Subject: Re: [PATCH v2] net: dp83640: expire old TX-skb

From: Andrew Lunn <[email-masked]>
Date: Fri, 1 Feb 2019 22:15:51 +0100

On Fri, Feb 01, 2019 at 10:09:18PM +0100, Sebastian Andrzej Siewior wrote:
> During sendmsg() a cloned skb is saved via dp83640_txtstamp() in
> ->tx_queue. After the NIC sends this packet, the PHY will reply with a
> timestamp for that TX packet. If the cable is pulled at the right time I
> don't see that packet. It might gets flushed as part of queue shutdown
> on NIC's side.
> Once the link is up again then after the next sendmsg() we enqueue
> another skb in dp83640_txtstamp() and have two on the list. Then the PHY
> will send a reply and decode_txts() attaches it to the first skb on the
> list.
> No crash occurs since refcounting works but we are one packet behind.
> linuxptp/ptp4l usually closes the socket and opens a new one (in such a
> timeout case) so those "stale" replies never get there. However it does
> not resume normal operation anymore.
> 
> Purge old skbs in decode_txts().
> 
> Cc: [email-masked]
> Signed-off-by: Sebastian Andrzej Siewior <[email-masked]>
> Reviewed-by: Kurt Kanzenbach <[email-masked]>

Hi Sebastian

netdev does not use the Cc: [email-masked].

https://www.kernel.org/doc/Documentation/networking/netdev-FAQ.txt

Please include a Fixes: tag, and a subject of [PATCH net] ...

Thanks
       Andrew