From b22cfcfcae5b2c1e9b43543b6a23e5ef517de8f8 Mon Sep 17 00:00:00 2001 From: Eliad Peller Date: Sun, 9 Sep 2012 14:43:51 +0300 Subject: [PATCH] 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 Signed-off-by: Eliad Peller Signed-off-by: Johannes Berg --- 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 d747da5..6f8a73c 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -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); /* 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; -- 2.7.4