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mac80211: disentangle iflist_mtx and chanctx_mtx

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At least on iwlwifi, sometimes lockdep complains that we can
lock
 chanctx_mtx -> mvm.mutex -> iflist_mtx
 (due to iterate_interfaces)
and
 iflist_mtx -> chanctx_mtx

Remove the latter dependency in mac80211 by using the RTNL
that we already hold in one case, and can relatively easily
achieve in the other case.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2017-04-26 10:58:53 +03:00
parent cf147085fd
commit 4a19906823
3 changed files with 9 additions and 8 deletions
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6
net/mac80211/cfg.c
View file

@ -739,11 +739,8 @@ static int ieee80211_set_monitor_channel(struct wiphy *wiphy,
return 0;
mutex_lock(&local->mtx);
mutex_lock(&local->iflist_mtx);
if (local->use_chanctx) {
sdata = rcu_dereference_protected(
local->monitor_sdata,
lockdep_is_held(&local->iflist_mtx));
sdata = rtnl_dereference(local->monitor_sdata);
if (sdata) {
ieee80211_vif_release_channel(sdata);
ret = ieee80211_vif_use_channel(sdata, chandef,
@ -756,7 +753,6 @@ static int ieee80211_set_monitor_channel(struct wiphy *wiphy,
if (ret == 0)
local->monitor_chandef = *chandef;
mutex_unlock(&local->iflist_mtx);
mutex_unlock(&local->mtx);
return ret;

2
net/mac80211/main.c
View file

@ -253,6 +253,7 @@ static void ieee80211_restart_work(struct work_struct *work)
WARN(test_bit(SCAN_HW_SCANNING, &local->scanning),
"%s called with hardware scan in progress\n", __func__);
flush_work(&local->radar_detected_work);
rtnl_lock();
list_for_each_entry(sdata, &local->interfaces, list)
flush_delayed_work(&sdata->dec_tailroom_needed_wk);
@ -1187,6 +1188,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
cancel_work_sync(&local->reconfig_filter);
cancel_work_sync(&local->tdls_chsw_work);
flush_work(&local->sched_scan_stopped_work);
flush_work(&local->radar_detected_work);
ieee80211_clear_tx_pending(local);
rate_control_deinitialize(local);

9
net/mac80211/util.c
View file

@ -2791,8 +2791,10 @@ void ieee80211_dfs_cac_cancel(struct ieee80211_local *local)
struct ieee80211_sub_if_data *sdata;
struct cfg80211_chan_def chandef;
/* for interface list, to avoid linking iflist_mtx and chanctx_mtx */
ASSERT_RTNL();
mutex_lock(&local->mtx);
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
/* it might be waiting for the local->mtx, but then
* by the time it gets it, sdata->wdev.cac_started
@ -2809,7 +2811,6 @@ void ieee80211_dfs_cac_cancel(struct ieee80211_local *local)
GFP_KERNEL);
}
}
mutex_unlock(&local->iflist_mtx);
mutex_unlock(&local->mtx);
}
@ -2831,7 +2832,9 @@ void ieee80211_dfs_radar_detected_work(struct work_struct *work)
}
mutex_unlock(&local->chanctx_mtx);
rtnl_lock();
ieee80211_dfs_cac_cancel(local);
rtnl_unlock();
if (num_chanctx > 1)
/* XXX: multi-channel is not supported yet */
@ -2846,7 +2849,7 @@ void ieee80211_radar_detected(struct ieee80211_hw *hw)
trace_api_radar_detected(local);
ieee80211_queue_work(hw, &local->radar_detected_work);
schedule_work(&local->radar_detected_work);
}
EXPORT_SYMBOL(ieee80211_radar_detected);