Commit ecccd072 authored by Thomas Pedersen's avatar Thomas Pedersen Committed by Johannes Berg
Browse files

mac80211: fix mesh deadlock 



The patch "cfg80211/mac80211: use cfg80211 wdev mutex in
mac80211" introduced several deadlocks by converting the
ifmsh->mtx to wdev->mtx. Solve these by:

1. drop the cancel_work_sync() in ieee80211_stop_mesh().
   Instead make the mesh work conditional on whether the mesh
   is running or not.
2. lock the mesh work with sdata_lock() to protect beacon
   updates and prevent races with wdev->mesh_id_len or
   cfg80211.

Signed-off-by: default avatarThomas Pedersen <thomas@cozybit.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 780b40df

net/mac80211/mesh.c

+17 −12
Original line number Diff line number Diff line
@@ -579,9 +579,7 @@ static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata) 
	mesh_path_expire(sdata);



	changed = mesh_accept_plinks_update(sdata);

	sdata_lock(sdata);

	ieee80211_mbss_info_change_notify(sdata, changed);

	sdata_unlock(sdata);



	mod_timer(&ifmsh->housekeeping_timer,

		  round_jiffies(jiffies +
@@ -788,12 +786,10 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata) 
	sdata->vif.bss_conf.enable_beacon = false;

	clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);

	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);

	sdata_lock(sdata);

	bcn = rcu_dereference_protected(ifmsh->beacon,

					lockdep_is_held(&sdata->wdev.mtx));

	rcu_assign_pointer(ifmsh->beacon, NULL);

	kfree_rcu(bcn, rcu_head);

	sdata_unlock(sdata);



	/* flush STAs and mpaths on this iface */

	sta_info_flush(sdata);
@@ -806,14 +802,6 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata) 
	del_timer_sync(&sdata->u.mesh.housekeeping_timer);

	del_timer_sync(&sdata->u.mesh.mesh_path_root_timer);

	del_timer_sync(&sdata->u.mesh.mesh_path_timer);

	/*

	 * If the timer fired while we waited for it, it will have

	 * requeued the work. Now the work will be running again

	 * but will not rearm the timer again because it checks

	 * whether the interface is running, which, at this point,

	 * it no longer is.

	 */

	cancel_work_sync(&sdata->work);



	local->fif_other_bss--;

	atomic_dec(&local->iff_allmultis);
@@ -954,6 +942,12 @@ void ieee80211_mesh_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata, 
	struct ieee80211_mgmt *mgmt;

	u16 stype;



	sdata_lock(sdata);



	/* mesh already went down */

	if (!sdata->wdev.mesh_id_len)

		goto out;



	rx_status = IEEE80211_SKB_RXCB(skb);

	mgmt = (struct ieee80211_mgmt *) skb->data;

	stype = le16_to_cpu(mgmt->frame_control) & IEEE80211_FCTL_STYPE;
@@ -971,12 +965,20 @@ void ieee80211_mesh_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata, 
		ieee80211_mesh_rx_mgmt_action(sdata, mgmt, skb->len, rx_status);

		break;

	}

out:

	sdata_unlock(sdata);

}



void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata)

{

	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;



	sdata_lock(sdata);



	/* mesh already went down */

	if (!sdata->wdev.mesh_id_len)

		goto out;



	if (ifmsh->preq_queue_len &&

	    time_after(jiffies,

		       ifmsh->last_preq + msecs_to_jiffies(ifmsh->mshcfg.dot11MeshHWMPpreqMinInterval)))
@@ -996,6 +998,9 @@ void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata) 


	if (test_and_clear_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags))

		mesh_sync_adjust_tbtt(sdata);



out:

	sdata_unlock(sdata);

}



void ieee80211_mesh_notify_scan_completed(struct ieee80211_local *local)

net/mac80211/mesh_plink.c

+1 −6
Original line number Diff line number Diff line
@@ -517,9 +517,7 @@ void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata, 
	ieee80211_mps_frame_release(sta, elems);

out:

	rcu_read_unlock();

	sdata_lock(sdata);

	ieee80211_mbss_info_change_notify(sdata, changed);

	sdata_unlock(sdata);

}



static void mesh_plink_timer(unsigned long data)
@@ -1070,9 +1068,6 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, 


	rcu_read_unlock();



	if (changed) {

		sdata_lock(sdata);

	if (changed)

		ieee80211_mbss_info_change_notify(sdata, changed);

		sdata_unlock(sdata);

	}

}

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