[RESENT] net: tuntap: Fix tun_net_fix_features()

tun->set_features are meant to limit not force the features.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Michael S. Tsirkin <mst@redhat.com>

---
 drivers/net/tun.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

On Mon, 2011-06-20 at 21:14 +0200, Michał Mirosław wrote:
> tun->set_features are meant to limit not force the features.
>
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> 
> ---
>  drivers/net/tun.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 4dab85e..56981c2 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -458,7 +458,7 @@ static u32 tun_net_fix_features(struct net_device *dev, u32 features)
>  {
>  	struct tun_struct *tun = netdev_priv(dev);
>  
> -	return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
> +	return features & (tun->set_features | ~TUN_USER_FEATURES);

(A & B) | (A & C) <=> A & (B | C)

This is a cosmetic change, not a fix.  Maybe you think it is clearer but
then you should say that in the commit message.

Ben.

>  }
>  
>  static const struct net_device_ops tun_netdev_ops = {

On Mon, Jun 20, 2011 at 08:25:06PM +0100, Ben Hutchings wrote:
> On Mon, 2011-06-20 at 21:14 +0200, Michał Mirosław wrote:
> > tun->set_features are meant to limit not force the features.
> >
> > Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
> > Acked-by: Michael S. Tsirkin <mst@redhat.com>
> > 
> > ---
> >  drivers/net/tun.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> > index 4dab85e..56981c2 100644
> > --- a/drivers/net/tun.c
> > +++ b/drivers/net/tun.c
> > @@ -458,7 +458,7 @@ static u32 tun_net_fix_features(struct net_device *dev, u32 features)
> >  {
> >  	struct tun_struct *tun = netdev_priv(dev);
> >  
> > -	return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
> > +	return features & (tun->set_features | ~TUN_USER_FEATURES);
> 
> (A & B) | (A & C) <=> A & (B | C)
> 
> This is a cosmetic change, not a fix.  Maybe you think it is clearer but
> then you should say that in the commit message.

Hmm. Noise through my braincells, I suppose. Let's just drop this patch.

Best Regards,
Michał Mirosław
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