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: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 73a597b..d5faf91 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -579,9 +579,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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)