Re: question about napi_disable (was Re: [PATCH] virtio_net: set/cancel work on ndo_open/ndo_stop)

[Jason Wang <jasowang@xxxxxxxxxx>]

On 04/04/2012 05:32 PM, Michael S. Tsirkin wrote:
> On Thu, Dec 29, 2011 at 09:12:38PM +1030, Rusty Russell wrote:
> > >  Michael S. Tsirkin noticed that we could run the refill work after
> > >  ndo_close, which can re-enable napi - we don't disable it until
> > >  virtnet_remove.  This is clearly wrong, so move the workqueue control
> > >  to ndo_open and ndo_stop (aka. virtnet_open and virtnet_close).
> > >  
> > >  One subtle point: virtnet_probe() could simply fail if it couldn't
> > >  allocate a receive buffer, but that's less polite in virtnet_open() so
> > >  we schedule a refill as we do in the normal receive path if we run out
> > >  of memory.
> > >  
> > >  Signed-off-by: Rusty Russell<rusty@xxxxxxxxxxxxxxx>
> Doh.
> napi_disable does not prevent the following
> napi_schedule, does it?
>
> Can someone confirm that I am not seeing things please?
Looks like napi_disable() does prevent the following scheduling, as 
napi_schedule_prep() returns true only when there's an 0 -> 1 transition 
of NAPI_STATE_SCHED bit.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html