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mac80211: fix station destruction in AP/mesh modes

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Unfortunately, commit b22cfcfcae, intended to speed up roaming
by avoiding the synchronize_rcu() broke AP/mesh modes as it moved
some code into that work item that will still call into the driver
at a time where it's no longer expected to handle this: after the
AP or mesh has been stopped.

To fix this problem remove the per-station work struct, maintain a
station cleanup list instead and flush this list when stations are
flushed. To keep this patch smaller for stable, do this when the
stations are flushed (sta_info_flush()). This unfortunately brings
back the original roaming delay; I'll fix that again in a separate
patch.

Also, Ben reported that the original commit could sometimes (with
many interfaces) cause long delays when an interface is set down,
due to blocking on flush_workqueue(). Since we now maintain the
cleanup list, this particular change of the original patch can be
reverted.

Cc: stable@vger.kernel.org [3.7]
Reported-by: Ben Greear <greearb@candelatech.com>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg
2012-12-13 22:54:58 +01:00
parent b7cfcd113a
commit 97f97b1f5f
4 changed files with 62 additions and 17 deletions
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28
net/mac80211/iface.c
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@@ -868,20 +868,11 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
cancel_work_sync(&sdata->work);
/*
* When we get here, the interface is marked down.
* Call rcu_barrier() to wait both for the RX path
* Call synchronize_rcu() to wait for the RX path
* should it be using the interface and enqueuing
* frames at this very time on another CPU, and
* for the sta free call_rcu callbacks.
* frames at this very time on another CPU.
*/
rcu_barrier();
/*
* free_sta_rcu() enqueues a work for the actual
* sta cleanup, so we need to flush it while
* sdata is still valid.
*/
flush_workqueue(local->workqueue);
synchronize_rcu();
skb_queue_purge(&sdata->skb_queue);
/*
@@ -1501,6 +1492,15 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
mutex_unlock(&local->iflist_mtx);
}
static void ieee80211_cleanup_sdata_stas_wk(struct work_struct *wk)
{
struct ieee80211_sub_if_data *sdata;
sdata = container_of(wk, struct ieee80211_sub_if_data, cleanup_stations_wk);
ieee80211_cleanup_sdata_stas(sdata);
}
int ieee80211_if_add(struct ieee80211_local *local, const char *name,
struct wireless_dev **new_wdev, enum nl80211_iftype type,
struct vif_params *params)
@@ -1576,6 +1576,10 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
INIT_LIST_HEAD(&sdata->key_list);
spin_lock_init(&sdata->cleanup_stations_lock);
INIT_LIST_HEAD(&sdata->cleanup_stations);
INIT_WORK(&sdata->cleanup_stations_wk, ieee80211_cleanup_sdata_stas_wk);
for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
struct ieee80211_supported_band *sband;
sband = local->hw.wiphy->bands[i];