From: Lars Persson <[email protected]>
Date: Fri, 1 Dec 2017 11:12:44 +0100
> The mss variable tracks the last max segment size sent to the TSO
> engine. We do not update the hardware as long as we receive skb:s with
> the same value in gso_size.
>
> During a network device down/up cycle (mapped to stmmac_release() and
> stmmac_open() callbacks) we issue a reset to the hardware and it
> forgets the setting for mss. However we did not zero out our mss
> variable so the next transmission of a gso packet happens with an
> undefined hardware setting.
>
> This triggers a hang in the TSO engine and eventuelly the netdev
> watchdog will bark.
>
> Fixes: f748be531d70 ("stmmac: support new GMAC4")
> Signed-off-by: Lars Persson <[email protected]>
Applied and queued up for -stable, thanks.
