diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index 5eaa1673a8f55e9217768aa8973423ed5d08fc51..d469d9d2b499c2d525bd2d1b3c3211bff8dd32c1 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -368,93 +368,90 @@ static void sta_info_finish_work(struct work_struct *work) mutex_unlock(&local->sta_mtx); } -int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU) +static int sta_info_insert_check(struct sta_info *sta) { - struct ieee80211_local *local = sta->local; struct ieee80211_sub_if_data *sdata = sta->sdata; - unsigned long flags; - int err = 0; /* * Can't be a WARN_ON because it can be triggered through a race: * something inserts a STA (on one CPU) without holding the RTNL * and another CPU turns off the net device. */ - if (unlikely(!ieee80211_sdata_running(sdata))) { - err = -ENETDOWN; - rcu_read_lock(); - goto out_free; - } + if (unlikely(!ieee80211_sdata_running(sdata))) + return -ENETDOWN; if (WARN_ON(compare_ether_addr(sta->sta.addr, sdata->vif.addr) == 0 || - is_multicast_ether_addr(sta->sta.addr))) { - err = -EINVAL; + is_multicast_ether_addr(sta->sta.addr))) + return -EINVAL; + + return 0; +} + +static int sta_info_insert_ibss(struct sta_info *sta) __acquires(RCU) +{ + struct ieee80211_local *local = sta->local; + struct ieee80211_sub_if_data *sdata = sta->sdata; + unsigned long flags; + + spin_lock_irqsave(&local->sta_lock, flags); + /* check if STA exists already */ + if (sta_info_get_bss(sdata, sta->sta.addr)) { + spin_unlock_irqrestore(&local->sta_lock, flags); rcu_read_lock(); - goto out_free; + return -EEXIST; } - /* - * In ad-hoc mode, we sometimes need to insert stations - * from tasklet context from the RX path. To avoid races, - * always do so in that case -- see the comment below. - */ - if (sdata->vif.type == NL80211_IFTYPE_ADHOC) { - spin_lock_irqsave(&local->sta_lock, flags); - /* check if STA exists already */ - if (sta_info_get_bss(sdata, sta->sta.addr)) { - spin_unlock_irqrestore(&local->sta_lock, flags); - rcu_read_lock(); - err = -EEXIST; - goto out_free; - } - - local->num_sta++; - local->sta_generation++; - smp_mb(); - sta_info_hash_add(local, sta); + local->num_sta++; + local->sta_generation++; + smp_mb(); + sta_info_hash_add(local, sta); - list_add_tail(&sta->list, &local->sta_pending_list); + list_add_tail(&sta->list, &local->sta_pending_list); - rcu_read_lock(); - spin_unlock_irqrestore(&local->sta_lock, flags); + rcu_read_lock(); + spin_unlock_irqrestore(&local->sta_lock, flags); #ifdef CONFIG_MAC80211_VERBOSE_DEBUG - wiphy_debug(local->hw.wiphy, "Added IBSS STA %pM\n", - sta->sta.addr); + wiphy_debug(local->hw.wiphy, "Added IBSS STA %pM\n", + sta->sta.addr); #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */ - ieee80211_queue_work(&local->hw, &local->sta_finish_work); + ieee80211_queue_work(&local->hw, &local->sta_finish_work); - return 0; - } + return 0; +} + +/* + * should be called with sta_mtx locked + * this function replaces the mutex lock + * with a RCU lock + */ +static int sta_info_insert_non_ibss(struct sta_info *sta) __acquires(RCU) +{ + struct ieee80211_local *local = sta->local; + struct ieee80211_sub_if_data *sdata = sta->sdata; + unsigned long flags; + int err = 0; + + lockdep_assert_held(&local->sta_mtx); /* * On first glance, this will look racy, because the code - * below this point, which inserts a station with sleeping, + * in this function, which inserts a station with sleeping, * unlocks the sta_lock between checking existence in the * hash table and inserting into it. * * However, it is not racy against itself because it keeps - * the mutex locked. It still seems to race against the - * above code that atomically inserts the station... That, - * however, is not true because the above code can only - * be invoked for IBSS interfaces, and the below code will - * not be -- and the two do not race against each other as - * the hash table also keys off the interface. + * the mutex locked. */ - might_sleep(); - - mutex_lock(&local->sta_mtx); - spin_lock_irqsave(&local->sta_lock, flags); /* check if STA exists already */ if (sta_info_get_bss(sdata, sta->sta.addr)) { spin_unlock_irqrestore(&local->sta_lock, flags); mutex_unlock(&local->sta_mtx); rcu_read_lock(); - err = -EEXIST; - goto out_free; + return -EEXIST; } spin_unlock_irqrestore(&local->sta_lock, flags); @@ -463,7 +460,7 @@ int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU) if (err) { mutex_unlock(&local->sta_mtx); rcu_read_lock(); - goto out_free; + return err; } #ifdef CONFIG_MAC80211_VERBOSE_DEBUG @@ -477,6 +474,51 @@ int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU) if (ieee80211_vif_is_mesh(&sdata->vif)) mesh_accept_plinks_update(sdata); + return 0; +} + +int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU) +{ + struct ieee80211_local *local = sta->local; + struct ieee80211_sub_if_data *sdata = sta->sdata; + int err = 0; + + err = sta_info_insert_check(sta); + if (err) { + rcu_read_lock(); + goto out_free; + } + + /* + * In ad-hoc mode, we sometimes need to insert stations + * from tasklet context from the RX path. To avoid races, + * always do so in that case -- see the comment below. + */ + if (sdata->vif.type == NL80211_IFTYPE_ADHOC) { + err = sta_info_insert_ibss(sta); + if (err) + goto out_free; + + return 0; + } + + /* + * It might seem that the function called below is in race against + * the function call above that atomically inserts the station... That, + * however, is not true because the above code can only + * be invoked for IBSS interfaces, and the below code will + * not be -- and the two do not race against each other as + * the hash table also keys off the interface. + */ + + might_sleep(); + + mutex_lock(&local->sta_mtx); + + err = sta_info_insert_non_ibss(sta); + if (err) + goto out_free; + return 0; out_free: BUG_ON(!err);