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 <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index ee5b66a..a230a95 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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
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 @@
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)