Intel 82574L interface wedging on em 7.1.9/7.2.3 when MSIX enabled

Adrian Chadd adrian at
Tue Nov 8 19:30:31 UTC 2011

On 8 November 2011 09:21, Hooman Fazaeli <hoomanfazaeli at> wrote:

> With MSIX enabled, the link task (em_handle_link) does _not_ triggers
> _start when the link changes state from inactive to active (which it
> should).
> If if_snd quickly fills up during a temporary link loss, transmission is
> stopped forever and the driver never recovers from that state.
> The last patch should have reduced the frequency of the problem
> but it assumes every IFQ_ENQUEUE is followed by a if_start which
> is not a true assumption.

FWIW, I saw something very similar with the if_arge code port from
Linux. If the TX queue filled up and wasn't serviced before it hit
completely full, it was never drained.

It may be worthwhile auditing some of the other NIC drivers to ensure
this kind of situation isn't occuring. Especially if they came from
Linux. :-)

That's a great catch, I hope it finally fixes the if_em issues with MSIX. :-)


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