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linux/net/mac80211/chan.c

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cfg80211/mac80211: better channel handling Currently (all tested with hwsim) you can do stupid things like setting up an AP on a certain channel, then adding another virtual interface and making that associate on another channel -- this will make the beaconing to move channel but obviously without the necessary IEs data update. In order to improve this situation, first make the configuration APIs (cfg80211 and nl80211) aware of multi-channel operation -- we'll eventually need that in the future anyway. There's one userland API change and one API addition. The API change is that now SET_WIPHY must be called with virtual interface index rather than only wiphy index in order to take effect for that interface -- luckily all current users (hostapd) do that. For monitor interfaces, the old setting is preserved, but monitors are always slaved to other devices anyway so no guarantees. The second userland API change is the introduction of a per virtual interface SET_CHANNEL command, that hostapd should use going forward to make it easier to understand what's going on (it can automatically detect a kernel with this command). Other than mac80211, no existing cfg80211 drivers are affected by this change because they only allow a single virtual interface. mac80211, however, now needs to be aware that the channel settings are per interface now, and needs to disallow (for now) real multi-channel operation, which is another important part of this patch. One of the immediate benefits is that you can now start hostapd to operate on a hardware that already has a connection on another virtual interface, as long as you specify the same channel. Note that two things are left unhandled (this is an improvement -- not a complete fix): * different HT/no-HT modes currently you could start an HT AP and then connect to a non-HT network on the same channel which would configure the hardware for no HT; that can be fixed fairly easily * CSA An AP we're connected to on a virtual interface might indicate switching channels, and in that case we would follow it, regardless of how many other interfaces are operating; this requires more effort to fix but is pretty rare after all Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-05-05 13:25:02 +00:00
/*
* mac80211 - channel management
*/
mac80211: improve HT channel handling Currently, when one interface switches HT mode, all others will follow along. This is clearly undesirable, since the new one might switch to no-HT while another one is operating in HT. Address this issue by keeping track of the HT mode per interface, and allowing only changes that are compatible, i.e. switching into HT40+ is not possible when another interface is in HT40-, in that case the second one needs to fall back to HT20. Also, to allow drivers to know what's going on, store the per-interface HT mode (channel type) in the virtual interface's bss_conf. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-05-05 13:28:27 +00:00
#include <linux/nl80211.h>
cfg80211/mac80211: better channel handling Currently (all tested with hwsim) you can do stupid things like setting up an AP on a certain channel, then adding another virtual interface and making that associate on another channel -- this will make the beaconing to move channel but obviously without the necessary IEs data update. In order to improve this situation, first make the configuration APIs (cfg80211 and nl80211) aware of multi-channel operation -- we'll eventually need that in the future anyway. There's one userland API change and one API addition. The API change is that now SET_WIPHY must be called with virtual interface index rather than only wiphy index in order to take effect for that interface -- luckily all current users (hostapd) do that. For monitor interfaces, the old setting is preserved, but monitors are always slaved to other devices anyway so no guarantees. The second userland API change is the introduction of a per virtual interface SET_CHANNEL command, that hostapd should use going forward to make it easier to understand what's going on (it can automatically detect a kernel with this command). Other than mac80211, no existing cfg80211 drivers are affected by this change because they only allow a single virtual interface. mac80211, however, now needs to be aware that the channel settings are per interface now, and needs to disallow (for now) real multi-channel operation, which is another important part of this patch. One of the immediate benefits is that you can now start hostapd to operate on a hardware that already has a connection on another virtual interface, as long as you specify the same channel. Note that two things are left unhandled (this is an improvement -- not a complete fix): * different HT/no-HT modes currently you could start an HT AP and then connect to a non-HT network on the same channel which would configure the hardware for no HT; that can be fixed fairly easily * CSA An AP we're connected to on a virtual interface might indicate switching channels, and in that case we would follow it, regardless of how many other interfaces are operating; this requires more effort to fix but is pretty rare after all Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-05-05 13:25:02 +00:00
#include "ieee80211_i.h"
enum ieee80211_chan_mode
__ieee80211_get_channel_mode(struct ieee80211_local *local,
struct ieee80211_sub_if_data *ignore)
{
struct ieee80211_sub_if_data *sdata;
WARN_ON(!mutex_is_locked(&local->iflist_mtx));
list_for_each_entry(sdata, &local->interfaces, list) {
if (sdata == ignore)
continue;
if (!ieee80211_sdata_running(sdata))
continue;
if (sdata->vif.type == NL80211_IFTYPE_MONITOR)
continue;
if (sdata->vif.type == NL80211_IFTYPE_STATION &&
!sdata->u.mgd.associated)
continue;
if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
if (!sdata->u.ibss.ssid_len)
continue;
if (!sdata->u.ibss.fixed_channel)
return CHAN_MODE_HOPPING;
}
if (sdata->vif.type == NL80211_IFTYPE_AP &&
!sdata->u.ap.beacon)
continue;
return CHAN_MODE_FIXED;
}
return CHAN_MODE_UNDEFINED;
}
enum ieee80211_chan_mode
ieee80211_get_channel_mode(struct ieee80211_local *local,
struct ieee80211_sub_if_data *ignore)
{
enum ieee80211_chan_mode mode;
mutex_lock(&local->iflist_mtx);
mode = __ieee80211_get_channel_mode(local, ignore);
mutex_unlock(&local->iflist_mtx);
return mode;
}
mac80211: improve HT channel handling Currently, when one interface switches HT mode, all others will follow along. This is clearly undesirable, since the new one might switch to no-HT while another one is operating in HT. Address this issue by keeping track of the HT mode per interface, and allowing only changes that are compatible, i.e. switching into HT40+ is not possible when another interface is in HT40-, in that case the second one needs to fall back to HT20. Also, to allow drivers to know what's going on, store the per-interface HT mode (channel type) in the virtual interface's bss_conf. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-05-05 13:28:27 +00:00
bool ieee80211_set_channel_type(struct ieee80211_local *local,
struct ieee80211_sub_if_data *sdata,
enum nl80211_channel_type chantype)
{
struct ieee80211_sub_if_data *tmp;
enum nl80211_channel_type superchan = NL80211_CHAN_NO_HT;
bool result;
mutex_lock(&local->iflist_mtx);
list_for_each_entry(tmp, &local->interfaces, list) {
if (tmp == sdata)
continue;
if (!ieee80211_sdata_running(tmp))
continue;
switch (tmp->vif.bss_conf.channel_type) {
case NL80211_CHAN_NO_HT:
case NL80211_CHAN_HT20:
superchan = tmp->vif.bss_conf.channel_type;
break;
case NL80211_CHAN_HT40PLUS:
WARN_ON(superchan == NL80211_CHAN_HT40MINUS);
superchan = NL80211_CHAN_HT40PLUS;
break;
case NL80211_CHAN_HT40MINUS:
WARN_ON(superchan == NL80211_CHAN_HT40PLUS);
superchan = NL80211_CHAN_HT40MINUS;
break;
}
}
switch (superchan) {
case NL80211_CHAN_NO_HT:
case NL80211_CHAN_HT20:
/*
* allow any change that doesn't go to no-HT
* (if it already is no-HT no change is needed)
*/
if (chantype == NL80211_CHAN_NO_HT)
break;
superchan = chantype;
break;
case NL80211_CHAN_HT40PLUS:
case NL80211_CHAN_HT40MINUS:
/* allow smaller bandwidth and same */
if (chantype == NL80211_CHAN_NO_HT)
break;
if (chantype == NL80211_CHAN_HT20)
break;
if (superchan == chantype)
break;
result = false;
goto out;
}
local->_oper_channel_type = superchan;
if (sdata)
sdata->vif.bss_conf.channel_type = chantype;
result = true;
out:
mutex_unlock(&local->iflist_mtx);
return result;
}
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