Subject: Re: [PATCH 1/7] mac80211: add helpers for frame control testing
From: Johannes Berg <johannes@sipsolutions.net>
To: Harvey Harrison <harvey.harrison@gmail.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>
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Date: Mon, 09 Jun 2008 19:21:25 +0200
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On Mon, 2008-06-09 at 09:31 -0700, Harvey Harrison wrote:
> On Mon, 2008-06-09 at 09:41 +0200, Johannes Berg wrote:
> > > +static inline int ieee80211_data_has_qos(__le16 fc)
> > > +{
> > > +	/*
> > > +	 * mask with QOS_DATA rather than IEEE80211_FCTL_STYPE as we just n=
eed
> > > +	 * to check the one bit
> > > +	 */
> > > +	return (fc &
> > > +	       cpu_to_le16(IEEE80211_FCTL_FTYPE | IEEE80211_STYPE_QOS_DATA)=
) =3D=3D
> > > +	       cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_DATA)=
;
> > > +}
> >=20
> > Shouldn't that rather be _is_qos_data?
> >=20
>=20
> I don't think so....I was trying to keep it so _is_ meant an exact compar=
ison and
> _has_ was checking the presence of particular bits.
>=20
> As this helper only checks for the one bit being set, I chose _has_.

Hmm. As far as I can tell, it checks that the frame is a QoS controlled
data frame. Hence, it explicitly checks that it _is_ a data frame and
_has_ the QoS bit, but in 802.11 lingo I think that means it _is_ a
"data+qos" frame.

johannes

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