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mac80211: use call_rcu() on sta deletion 

mac80211 calls synchronize_rcu() on sta deletion,
which increase the roaming time significantly.

Convert it into a call_rcu() mechanism, in order
to avoid blocking. Since some of the cleanup
functions might sleep, schedule from the call_rcu
callback a new work that will do the actual cleanup.

In order to make sure the cleanup occurs before
the interface went down, flush local->workqueue
on ieee80211_do_stop().

Signed-off-by: Yoni Divinsky <yoni.divinsky@ti.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Eliad Peller 2012-09-09 14:43:51 +03:00 committed by Johannes Berg
parent e548c49e6d
commit b22cfcfcae
3 changed files with 81 additions and 57 deletions
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15
net/mac80211/iface.c
View File

@ -793,11 +793,20 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
flush_work(&sdata->work);
/*
* When we get here, the interface is marked down.
* Call synchronize_rcu() to wait for the RX path
* Call rcu_barrier() to wait both for the RX path
* should it be using the interface and enqueuing
* frames at this very time on another CPU.
* frames at this very time on another CPU, and
* for the sta free call_rcu callbacks.
*/
synchronize_rcu();
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);
skb_queue_purge(&sdata->skb_queue);
/*

121
net/mac80211/sta_info.c
View File

@ -91,6 +91,70 @@ static int sta_info_hash_del(struct ieee80211_local *local,
return -ENOENT;
}
static void free_sta_work(struct work_struct *wk)
{
struct sta_info *sta = container_of(wk, struct sta_info, free_sta_wk);
int ac, i;
struct tid_ampdu_tx *tid_tx;
struct ieee80211_sub_if_data *sdata = sta->sdata;
struct ieee80211_local *local = sdata->local;
/*
* At this point, when being called as call_rcu callback,
* neither mac80211 nor the driver can reference this
* sta struct any more except by still existing timers
* associated with this station that we clean up below.
*/
if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
BUG_ON(!sdata->bss);
clear_sta_flag(sta, WLAN_STA_PS_STA);
atomic_dec(&sdata->bss->num_sta_ps);
sta_info_recalc_tim(sta);
}
for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
local->total_ps_buffered -= skb_queue_len(&sta->ps_tx_buf[ac]);
__skb_queue_purge(&sta->ps_tx_buf[ac]);
__skb_queue_purge(&sta->tx_filtered[ac]);
}
#ifdef CONFIG_MAC80211_MESH
if (ieee80211_vif_is_mesh(&sdata->vif)) {
mesh_accept_plinks_update(sdata);
mesh_plink_deactivate(sta);
del_timer_sync(&sta->plink_timer);
}
#endif
cancel_work_sync(&sta->drv_unblock_wk);
/*
* Destroy aggregation state here. It would be nice to wait for the
* driver to finish aggregation stop and then clean up, but for now
* drivers have to handle aggregation stop being requested, followed
* directly by station destruction.
*/
for (i = 0; i < STA_TID_NUM; i++) {
tid_tx = rcu_dereference_raw(sta->ampdu_mlme.tid_tx[i]);
if (!tid_tx)
continue;
__skb_queue_purge(&tid_tx->pending);
kfree(tid_tx);
}
sta_info_free(local, sta);
}
static void free_sta_rcu(struct rcu_head *h)
{
struct sta_info *sta = container_of(h, struct sta_info, rcu_head);
ieee80211_queue_work(&sta->local->hw, &sta->free_sta_wk);
}
/* protected by RCU */
struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
const u8 *addr)
@ -241,6 +305,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
spin_lock_init(&sta->lock);
INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
INIT_WORK(&sta->free_sta_wk, free_sta_work);
INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
mutex_init(&sta->ampdu_mlme.mtx);
@ -654,8 +719,7 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
{
struct ieee80211_local *local;
struct ieee80211_sub_if_data *sdata;
int ret, i, ac;
struct tid_ampdu_tx *tid_tx;
int ret, i;
might_sleep();
@ -711,65 +775,14 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
WARN_ON_ONCE(ret != 0);
}
/*
* At this point, after we wait for an RCU grace period,
* neither mac80211 nor the driver can reference this
* sta struct any more except by still existing timers
* associated with this station that we clean up below.
*/
synchronize_rcu();
if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
BUG_ON(!sdata->bss);
clear_sta_flag(sta, WLAN_STA_PS_STA);
atomic_dec(&sdata->bss->num_sta_ps);
sta_info_recalc_tim(sta);
}
for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
local->total_ps_buffered -= skb_queue_len(&sta->ps_tx_buf[ac]);
__skb_queue_purge(&sta->ps_tx_buf[ac]);
__skb_queue_purge(&sta->tx_filtered[ac]);
}
#ifdef CONFIG_MAC80211_MESH
if (ieee80211_vif_is_mesh(&sdata->vif))
mesh_accept_plinks_update(sdata);
#endif
sta_dbg(sdata, "Removed STA %pM\n", sta->sta.addr);
cancel_work_sync(&sta->drv_unblock_wk);
cfg80211_del_sta(sdata->dev, sta->sta.addr, GFP_KERNEL);
rate_control_remove_sta_debugfs(sta);
ieee80211_sta_debugfs_remove(sta);
#ifdef CONFIG_MAC80211_MESH
if (ieee80211_vif_is_mesh(&sta->sdata->vif)) {
mesh_plink_deactivate(sta);
del_timer_sync(&sta->plink_timer);
}
#endif
/*
* Destroy aggregation state here. It would be nice to wait for the
* driver to finish aggregation stop and then clean up, but for now
* drivers have to handle aggregation stop being requested, followed
* directly by station destruction.
*/
for (i = 0; i < STA_TID_NUM; i++) {
tid_tx = rcu_dereference_raw(sta->ampdu_mlme.tid_tx[i]);
if (!tid_tx)
continue;
__skb_queue_purge(&tid_tx->pending);
kfree(tid_tx);
}
sta_info_free(local, sta);
call_rcu(&sta->rcu_head, free_sta_rcu);
return 0;
}

2
net/mac80211/sta_info.h
View File

@ -287,6 +287,7 @@ struct sta_ampdu_mlme {
struct sta_info {
/* General information, mostly static */
struct list_head list;
struct rcu_head rcu_head;
struct sta_info __rcu *hnext;
struct ieee80211_local *local;
struct ieee80211_sub_if_data *sdata;
@ -297,6 +298,7 @@ struct sta_info {
spinlock_t lock;
struct work_struct drv_unblock_wk;
struct work_struct free_sta_wk;
u16 listen_interval;