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mac80211: protect AP VLAN list with local->mtx

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It was impossible to change chanctx of master AP
for AP VLANs because the copy function requires
RTNL which can't be simply taken in mac80211 code
due to possible deadlocks.

This is required for future chanctx reservation
that re-bind vifs to new chanctx. This requires
safe AP VLAN iteration without RTNL.

Now VLANs can be iterated while holding either
RTNL or local->mtx because the list is modified
while holding both of these locks.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Michal Kazior 2014-03-05 13:14:08 +01:00 committed by Johannes Berg
parent b6a550156b
commit 4e141dad26
4 changed files with 14 additions and 6 deletions
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5
net/mac80211/cfg.c
View file

@ -983,10 +983,11 @@ static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
mutex_lock(&local->mtx);
err = ieee80211_vif_use_channel(sdata, &params->chandef,
IEEE80211_CHANCTX_SHARED);
if (!err)
ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
mutex_unlock(&local->mtx);
if (err)
return err;
ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
/*
* Apply control port protocol, this allows us to
@ -1139,8 +1140,8 @@ static int ieee80211_stop_ap(struct wiphy *wiphy, struct net_device *dev)
local->total_ps_buffered -= skb_queue_len(&sdata->u.ap.ps.bc_buf);
skb_queue_purge(&sdata->u.ap.ps.bc_buf);
ieee80211_vif_copy_chanctx_to_vlans(sdata, true);
mutex_lock(&local->mtx);
ieee80211_vif_copy_chanctx_to_vlans(sdata, true);
ieee80211_vif_release_channel(sdata);
mutex_unlock(&local->mtx);

2
net/mac80211/chan.c
View file

@ -712,7 +712,7 @@ void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
struct ieee80211_sub_if_data *vlan;
struct ieee80211_chanctx_conf *conf;
ASSERT_RTNL();
lockdep_assert_held(&local->mtx);
if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
return;

4
net/mac80211/ieee80211_i.h
View file

@ -260,7 +260,7 @@ struct ieee80211_if_ap {
/* to be used after channel switch. */
struct cfg80211_beacon_data *next_beacon;
struct list_head vlans;
struct list_head vlans; /* write-protected with RTNL and local->mtx */
struct ps_data ps;
atomic_t num_mcast_sta; /* number of stations receiving multicast */
@ -276,7 +276,7 @@ struct ieee80211_if_wds {
};
struct ieee80211_if_vlan {
struct list_head list;
struct list_head list; /* write-protected with RTNL and local->mtx */
/* used for all tx if the VLAN is configured to 4-addr mode */
struct sta_info __rcu *sta;

9
net/mac80211/iface.c
View file

@ -496,7 +496,9 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
if (!sdata->bss)
return -ENOLINK;
mutex_lock(&local->mtx);
list_add(&sdata->u.vlan.list, &sdata->bss->vlans);
mutex_unlock(&local->mtx);
master = container_of(sdata->bss,
struct ieee80211_sub_if_data, u.ap);
@ -726,8 +728,11 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
drv_stop(local);
err_del_bss:
sdata->bss = NULL;
if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
mutex_lock(&local->mtx);
list_del(&sdata->u.vlan.list);
mutex_unlock(&local->mtx);
}
/* might already be clear but that doesn't matter */
clear_bit(SDATA_STATE_RUNNING, &sdata->state);
return res;
@ -879,7 +884,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
switch (sdata->vif.type) {
case NL80211_IFTYPE_AP_VLAN:
mutex_lock(&local->mtx);
list_del(&sdata->u.vlan.list);
mutex_unlock(&local->mtx);
RCU_INIT_POINTER(sdata->vif.chanctx_conf, NULL);
/* no need to tell driver */
break;