Re: [PATCH net-next 4/6] net: ipa: ensure hardware has power in ipa_start_xmit()

[Jakub Kicinski]

On Fri, 13 Aug 2021 21:25:23 -0500 Alex Elder wrote:
> > This is racy, what if the pm work gets scheduled on another CPU and
> > calls wake right here (i.e. before you call netif_stop_queue())?
> > The queue may never get woken up?  
> 
> I haven't been seeing this happen but I think you may be right.
> 
> I did think about this race, but I think I was relying on the
> PM work queue to somehow avoid the problem.  I need to think
> about this again after a good night's sleep.  I might need
> to add an atomic flag or something.

Maybe add a spin lock?  Seems like the whole wake up path will be
expensive enough for a spin lock to be in the noise. You can always 
add complexity later.