RE: [PATCH net-next] Add support for netvsc build without CONFIG_SYSFS flag

[Haiyang Zhang <haiyangz@microsoft.com>]

> -----Original Message-----
> From: Greg KH [mailto:greg@kroah.com]
> Sent: Thursday, May 8, 2014 5:13 AM
> To: Haiyang Zhang
> Cc: davem@davemloft.net; netdev@vger.kernel.org; olaf@aepfle.de;
> jasowang@redhat.com; driverdev-devel@linuxdriverproject.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH net-next] Add support for netvsc build without
> CONFIG_SYSFS flag
> 
> On Wed, May 07, 2014 at 03:45:04PM -0700, Haiyang Zhang wrote:
> > This change ensures the driver can be built successfully without the
> > CONFIG_SYSFS flag.
> > MS-TFS: 182270
> >
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
> > ---
> >  drivers/net/hyperv/hyperv_net.h   |    2 ++
> >  drivers/net/hyperv/netvsc_drv.c   |   12 +++++++++++-
> >  drivers/net/hyperv/rndis_filter.c |    4 ++--
> >  3 files changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/hyperv_net.h
> > b/drivers/net/hyperv/hyperv_net.h index 4b7df5a..23b96bc 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -87,6 +87,8 @@ struct ndis_recv_scale_cap { /*
> > NDIS_RECEIVE_SCALE_CAPABILITIES */  #define HASH_KEYLEN
> > NDIS_RSS_HASH_SECRET_KEY_MAX_SIZE_REVISION_2
> >  extern u8 netvsc_hash_key[];
> >
> > +extern unsigned int netvsc_num_queue;
> > +
> >  struct ndis_recv_scale_param { /* NDIS_RECEIVE_SCALE_PARAMETERS */
> >  	struct ndis_obj_header hdr;
> >
> > diff --git a/drivers/net/hyperv/netvsc_drv.c
> > b/drivers/net/hyperv/netvsc_drv.c index 939e3af..07896f3 100644
> > --- a/drivers/net/hyperv/netvsc_drv.c
> > +++ b/drivers/net/hyperv/netvsc_drv.c
> > @@ -52,6 +52,8 @@ static int ring_size = 128;  module_param(ring_size,
> > int, S_IRUGO);  MODULE_PARM_DESC(ring_size, "Ring buffer size (# of
> > pages)");
> >
> > +unsigned int netvsc_num_queue = 1;
> > +
> >  static void do_set_multicast(struct work_struct *w)  {
> >  	struct net_device_context *ndevctx = @@ -639,9 +641,11 @@ int
> > netvsc_recv_callback(struct hv_device *device_obj,
> >  		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
> >  				       packet->vlan_tci);
> >
> > +#ifdef CONFIG_SYSFS
> >  	skb_record_rx_queue(skb, packet->channel->
> >  			    offermsg.offer.sub_channel_index %
> >  			    net->real_num_rx_queues);
> > +#endif
> 
> Why is this a sysfs-only function?  It should have nothing to do with sysfs, right?
> So why would the driver care?

Without CONFIG_SYSFS the multi-receive queues are not allocated, see below, and 
the variable real_num_rx_queues is not defined, so we skip this function.

In alloc_netdev_mqs(), file "net/core/dev.c":
#ifdef CONFIG_SYSFS
        dev->num_rx_queues = rxqs;
        dev->real_num_rx_queues = rxqs;
        if (netif_alloc_rx_queues(dev))
                goto free_all;
#endif

> Don't put #ifdef in drivers, it's unmaintainable over time, if this really is a sysfs-
> only function, this should already be handled automatically in a .h file
> somewhere.

OK, I will move the #ifdef into hyperv_net.h.

Thanks,
- Haiyang