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@xxxxxx>
Signed-off-by: Eliad Peller <eliad@xxxxxxxxxx>
---
v2:
* replace synchronize_rcu with rcu_barrier (thanks Johannes!)
* fix/add comments
net/mac80211/iface.c | 15 +++++-
net/mac80211/sta_info.c | 121 ++++++++++++++++++++++++++---------------------
net/mac80211/sta_info.h | 2 +
3 files changed, 81 insertions(+), 57 deletions(-)
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 513b85e..732b4a0 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -769,11 +769,20 @@ 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);
/*
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 06fa75c..9c8cd8b 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -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;
}
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index a470e11..c88f161f 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -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;
--
1.7.6.401.g6a319
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