From 73651ee6396c499ccb59ebc84c9274db01ed026d Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 25 Feb 2008 16:27:47 +0100 Subject: mac80211: split sta_info_add sta_info_add() has two functions: allocating a station info structure and inserting it into the hash table/list. Splitting these two functions allows allocating with GFP_KERNEL in many places instead of GFP_ATOMIC which is now required by the RCU protection. Additionally, in many places RCU protection is now no longer needed at all because between sta_info_alloc() and sta_info_insert() the caller owns the structure. This fixes a few race conditions with setting initial flags and similar, but not all (see comments in ieee80211_sta.c and cfg.c). More documentation on the existing races will be in a follow-up patch. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/sta_info.c | 72 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 50 insertions(+), 22 deletions(-) (limited to 'net/mac80211/sta_info.c') diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index ee5b66abc0f..a230a959739 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -31,12 +31,13 @@ * for faster lookup and a list for iteration. They are managed using * RCU, i.e. access to the list and hash table is protected by RCU. * - * STA info structures are always "alive" when they are added with - * @sta_info_add() [this may be changed in the future to allow allocating - * outside of a critical section!], they are then added to the hash - * table and list. Therefore, @sta_info_add() must also be RCU protected, - * also, the caller of @sta_info_add() cannot assume that it owns the - * structure. + * Upon allocating a STA info structure with @sta_info_alloc() or + * mesh_plink_alloc(), the caller owns that structure. It must then either + * destroy it using @sta_info_destroy() (which is pretty useless) or insert + * it into the hash table using @sta_info_insert() which demotes the reference + * from ownership to a regular RCU-protected reference; if the function + * is called without protection by an RCU critical section the reference + * is instantly invalidated. * * Because there are debugfs entries for each station, and adding those * must be able to sleep, it is also possible to "pin" a station entry, @@ -131,6 +132,10 @@ void sta_info_destroy(struct sta_info *sta) struct ieee80211_local *local = sta->local; struct sk_buff *skb; int i; + DECLARE_MAC_BUF(mbuf); + + if (!sta) + return; ASSERT_RTNL(); might_sleep(); @@ -171,6 +176,11 @@ void sta_info_destroy(struct sta_info *sta) rate_control_free_sta(sta->rate_ctrl, sta->rate_ctrl_priv); rate_control_put(sta->rate_ctrl); +#ifdef CONFIG_MAC80211_VERBOSE_DEBUG + printk(KERN_DEBUG "%s: Destroyed STA %s\n", + wiphy_name(local->hw.wiphy), print_mac(mbuf, sta->addr)); +#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */ + kfree(sta); } @@ -183,18 +193,17 @@ static void sta_info_hash_add(struct ieee80211_local *local, rcu_assign_pointer(local->sta_hash[STA_HASH(sta->addr)], sta); } -struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata, - u8 *addr) +struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata, + u8 *addr, gfp_t gfp) { struct ieee80211_local *local = sdata->local; struct sta_info *sta; int i; - DECLARE_MAC_BUF(mac); - unsigned long flags; + DECLARE_MAC_BUF(mbuf); - sta = kzalloc(sizeof(*sta), GFP_ATOMIC); + sta = kzalloc(sizeof(*sta), gfp); if (!sta) - return ERR_PTR(-ENOMEM); + return NULL; memcpy(sta->addr, addr, ETH_ALEN); sta->local = local; @@ -202,11 +211,11 @@ struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata, sta->rate_ctrl = rate_control_get(local->rate_ctrl); sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl, - GFP_ATOMIC); + gfp); if (!sta->rate_ctrl_priv) { rate_control_put(sta->rate_ctrl); kfree(sta); - return ERR_PTR(-ENOMEM); + return NULL; } spin_lock_init(&sta->ampdu_mlme.ampdu_rx); @@ -233,11 +242,27 @@ struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata, } skb_queue_head_init(&sta->ps_tx_buf); skb_queue_head_init(&sta->tx_filtered); + +#ifdef CONFIG_MAC80211_VERBOSE_DEBUG + printk(KERN_DEBUG "%s: Allocated STA %s\n", + wiphy_name(local->hw.wiphy), print_mac(mbuf, sta->addr)); +#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */ + + return sta; +} + +int sta_info_insert(struct sta_info *sta) +{ + struct ieee80211_local *local = sta->local; + struct ieee80211_sub_if_data *sdata = sta->sdata; + unsigned long flags; + DECLARE_MAC_BUF(mac); + spin_lock_irqsave(&local->sta_lock, flags); /* check if STA exists already */ - if (__sta_info_find(local, addr)) { + if (__sta_info_find(local, sta->addr)) { spin_unlock_irqrestore(&local->sta_lock, flags); - return ERR_PTR(-EEXIST); + return -EEXIST; } list_add(&sta->list, &local->sta_list); local->num_sta++; @@ -249,16 +274,16 @@ struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata, sdata = sdata->u.vlan.ap; local->ops->sta_notify(local_to_hw(local), &sdata->vif, - STA_NOTIFY_ADD, addr); + STA_NOTIFY_ADD, sta->addr); } - spin_unlock_irqrestore(&local->sta_lock, flags); - #ifdef CONFIG_MAC80211_VERBOSE_DEBUG - printk(KERN_DEBUG "%s: Added STA %s\n", - wiphy_name(local->hw.wiphy), print_mac(mac, addr)); + printk(KERN_DEBUG "%s: Inserted STA %s\n", + wiphy_name(local->hw.wiphy), print_mac(mac, sta->addr)); #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */ + spin_unlock_irqrestore(&local->sta_lock, flags); + #ifdef CONFIG_MAC80211_DEBUGFS /* debugfs entry adding might sleep, so schedule process * context task for adding entry for STAs that do not yet @@ -266,7 +291,10 @@ struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata, queue_work(local->hw.workqueue, &local->sta_debugfs_add); #endif - return sta; + if (ieee80211_vif_is_mesh(&sdata->vif)) + mesh_accept_plinks_update(sdata); + + return 0; } static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid) -- cgit v1.2.3