netdev - Re: Proper suspend/resume flow

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Message-ID: <1396123694.2898.93.camel@deadeye.wl.decadent.org.uk>
Date:	Sat, 29 Mar 2014 20:08:14 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	netdev@...r.kernel.org
Subject: Re: Proper suspend/resume flow

On Sat, 2014-03-29 at 18:03 +0000, Russell King - ARM Linux wrote:
[...]
> That said, for the case where a network driver does all it's packet
> processing in the NAPI poll function, I think calling napi_disable()
> is a good way to ensure that the poll function is not running, and
> therefore there are can be no netif_wake_queue() calls - or anything
> other than the ndo_start_xmit touching the rings or the device.  This
> is needed anyway to stop receive packet processing looking at its
> ring.
> 
> So, I've now come to this sequence:
> 
> suspend()
> {
> 	if (netif_running()) {
> 		napi_disable();
> 		netif_tx_lock();
> 		netif_device_detach();
> 		netif_tx_unlock();
> 	}
> 	... suspend device ...
> }
[...]

This is missing netif_stop_queue(), but I assume you do that somewhere
after netif_device_detach().  I think this should work.

Ben.

-- 
Ben Hutchings
[W]e found...that it wasn't as easy to get programs right as we had thought.
... I realized that a large part of my life from then on was going to be spent
in finding mistakes in my own programs. - Maurice Wilkes, 1949

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