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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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9
net/mac80211/util.c
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@@ -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);