Subject: Re: [PATCH RFC v2] mac80211: no BSS changes to driver from beacons
	processed during scanning
From: Johannes Berg <johannes@sipsolutions.net>
To: Reinette Chatre <reinette.chatre@intel.com>
Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org
In-Reply-To: <1207785375-13470-1-git-send-email-reinette.chatre@intel.com>
References: <1207785375-13470-1-git-send-email-reinette.chatre@intel.com>
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Date: Fri, 11 Apr 2008 23:11:21 +0200
Message-Id: <1207948281.13354.98.camel@johannes.berg> (sfid-20080411_221200_493160_5ED18AAA)
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Sender: linux-wireless-owner@vger.kernel.org


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On Wed, 2008-04-09 at 16:56 -0700, Reinette Chatre wrote:
> There is no need to send BSS changes to driver from beacons processed
> during scanning. We are more interested in beacons from an AP with which
> we are associated - these will still be used to send updates to driver as
> the beacons are received without scanning.
>=20
> This change=C2=B7removes the requirement that bss_info_changed needs to b=
e atomic.
> The beacons received during scanning are processed from a tasklet, but if=
 we
> do not call bss_info_changed for these beacons there is no need for it to=
 be
> atomic. This function (bss_info_changed) is called either from workqueue =
or
> ioctl in all other instances.

Seems reasonable. Makes me itch to rewrite the scan code completely (as
I had already planned once) so that the mlme isn't full of it, we don't
do everything twice (master and regular device) and the context (tasklet
vs. workqueue) is clearer. Oh well, not right now.

> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
> Acked-by: Tomas Winkler <tomas.winkler@intel.com>

Acked-by: Johannes Berg <johannes@sipsolutions.net>

> ---
> This patch applies to the latest code after mac80211 filename changes.

Didn't think it would be much of a problem otherwise I wouldn't have
asked for it, was it?

>  include/net/mac80211.h |    3 +--
>  net/mac80211/mlme.c    |   16 +++++++++++-----
>  2 files changed, 12 insertions(+), 7 deletions(-)
>=20
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 079e7bd..4a80d74 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -1020,8 +1020,7 @@ enum ieee80211_ampdu_mlme_action {
>   *	level driver (e.g. assoc/disassoc status, erp parameters).
>   *	This function should not be used if no BSS has been set, unless
>   *	for association indication. The @changed parameter indicates which
> - *	of the bss parameters has changed when a call is made. This callback
> - *	has to be atomic.
> + *	of the bss parameters has changed when a call is made.
>   *
>   * @configure_filter: Configure the device's RX filter.
>   *	See the section "Frame filtering" for more information.
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 83e8b49..e3f2cb0 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -2797,6 +2797,17 @@ static void ieee80211_rx_mgmt_beacon(struct net_de=
vice *dev,
> =20
>  	ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);
> =20
> +	if (elems.wmm_param && (ifsta->flags & IEEE80211_STA_WMM_ENABLED)) {
> +		ieee80211_sta_wmm_params(dev, ifsta, elems.wmm_param,
> +					 elems.wmm_param_len);
> +	}
> +
> +	/* Do not send changes to driver if we are scanning. This removes
> +	 * requirement that driver's bss_info_changed function needs to be
> +	 * atomic. */
> +	if (local->sta_sw_scanning || local->sta_hw_scanning)
> +		return;
> +
>  	if (elems.erp_info && elems.erp_info_len >=3D 1)
>  		changed |=3D ieee80211_handle_erp_ie(sdata, elems.erp_info[0]);
>  	else {
> @@ -2816,11 +2827,6 @@ static void ieee80211_rx_mgmt_beacon(struct net_de=
vice *dev,
>  					       &bss_info);
>  	}
> =20
> -	if (elems.wmm_param && (ifsta->flags & IEEE80211_STA_WMM_ENABLED)) {
> -		ieee80211_sta_wmm_params(dev, ifsta, elems.wmm_param,
> -					 elems.wmm_param_len);
> -	}
> -
>  	ieee80211_bss_info_change_notify(sdata, changed);
>  }
> =20

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