lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

mac80211: split sta_info_add

Browse Source 
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>
This commit is contained in:
Johannes Berg
2008-02-25 16:27:47 +01:00
committed by John W. Linville
parent d0709a6518
commit 73651ee639
7 changed files with 166 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files

72
net/mac80211/sta_info.c
View File

@ -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)