From: Johannes Berg <johannes.berg@xxxxxxxxx>
Now that IBSS no longer needs to insert stations
from atomic context, we can get rid of all the
special cases for that, and even get rid of the
sta_lock (though it needs to stay as tim_lock.)
This makes the station management code much more
straight-forward.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
net/mac80211/ieee80211_i.h | 11 +--
net/mac80211/sta_info.c | 152 ++++-----------------------------------------
net/mac80211/tx.c | 4 -
3 files changed, 22 insertions(+), 145 deletions(-)
--- a/net/mac80211/sta_info.c 2011-12-14 13:58:04.000000000 +0100
+++ b/net/mac80211/sta_info.c 2011-12-14 14:03:28.000000000 +0100
@@ -62,14 +62,14 @@
* freed before they are done using it.
*/
-/* Caller must hold local->sta_lock */
+/* Caller must hold local->sta_mtx */
static int sta_info_hash_del(struct ieee80211_local *local,
struct sta_info *sta)
{
struct sta_info *s;
s = rcu_dereference_protected(local->sta_hash[STA_HASH(sta->sta.addr)],
- lockdep_is_held(&local->sta_lock));
+ lockdep_is_held(&local->sta_mtx));
if (!s)
return -ENOENT;
if (s == sta) {
@@ -81,7 +81,7 @@ static int sta_info_hash_del(struct ieee
while (rcu_access_pointer(s->hnext) &&
rcu_access_pointer(s->hnext) != sta)
s = rcu_dereference_protected(s->hnext,
- lockdep_is_held(&local->sta_lock));
+ lockdep_is_held(&local->sta_mtx));
if (rcu_access_pointer(s->hnext)) {
RCU_INIT_POINTER(s->hnext, sta->hnext);
return 0;
@@ -98,14 +98,12 @@ struct sta_info *sta_info_get(struct iee
struct sta_info *sta;
sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
while (sta) {
if (sta->sdata == sdata && !sta->dummy &&
memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
break;
sta = rcu_dereference_check(sta->hnext,
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
}
return sta;
@@ -119,14 +117,12 @@ struct sta_info *sta_info_get_rx(struct
struct sta_info *sta;
sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
while (sta) {
if (sta->sdata == sdata &&
memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
break;
sta = rcu_dereference_check(sta->hnext,
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
}
return sta;
@@ -143,7 +139,6 @@ struct sta_info *sta_info_get_bss(struct
struct sta_info *sta;
sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
while (sta) {
if ((sta->sdata == sdata ||
@@ -152,7 +147,6 @@ struct sta_info *sta_info_get_bss(struct
memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
break;
sta = rcu_dereference_check(sta->hnext,
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
}
return sta;
@@ -169,7 +163,6 @@ struct sta_info *sta_info_get_bss_rx(str
struct sta_info *sta;
sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
while (sta) {
if ((sta->sdata == sdata ||
@@ -177,7 +170,6 @@ struct sta_info *sta_info_get_bss_rx(str
memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
break;
sta = rcu_dereference_check(sta->hnext,
- lockdep_is_held(&local->sta_lock) ||
lockdep_is_held(&local->sta_mtx));
}
return sta;
@@ -228,10 +220,11 @@ void sta_info_free(struct ieee80211_loca
kfree(sta);
}
-/* Caller must hold local->sta_lock */
+/* Caller must hold local->sta_mtx */
static void sta_info_hash_add(struct ieee80211_local *local,
struct sta_info *sta)
{
+ lockdep_assert_held(&local->sta_mtx);
sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
RCU_INIT_POINTER(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
}
@@ -345,7 +338,6 @@ static int sta_info_finish_insert(struct
struct ieee80211_local *local = sta->local;
struct ieee80211_sub_if_data *sdata = sta->sdata;
struct station_info sinfo;
- unsigned long flags;
int err = 0;
lockdep_assert_held(&local->sta_mtx);
@@ -379,9 +371,7 @@ static int sta_info_finish_insert(struct
smp_mb();
/* make the station visible */
- spin_lock_irqsave(&local->sta_lock, flags);
sta_info_hash_add(local, sta);
- spin_unlock_irqrestore(&local->sta_lock, flags);
}
list_add(&sta->list, &local->sta_list);
@@ -402,35 +392,6 @@ static int sta_info_finish_insert(struct
return 0;
}
-static void sta_info_finish_pending(struct ieee80211_local *local)
-{
- struct sta_info *sta;
- unsigned long flags;
-
- spin_lock_irqsave(&local->sta_lock, flags);
- while (!list_empty(&local->sta_pending_list)) {
- sta = list_first_entry(&local->sta_pending_list,
- struct sta_info, list);
- list_del(&sta->list);
- spin_unlock_irqrestore(&local->sta_lock, flags);
-
- sta_info_finish_insert(sta, true, false);
-
- spin_lock_irqsave(&local->sta_lock, flags);
- }
- spin_unlock_irqrestore(&local->sta_lock, flags);
-}
-
-static void sta_info_finish_work(struct work_struct *work)
-{
- struct ieee80211_local *local =
- container_of(work, struct ieee80211_local, sta_finish_work);
-
- mutex_lock(&local->sta_mtx);
- sta_info_finish_pending(local);
- mutex_unlock(&local->sta_mtx);
-}
-
static int sta_info_insert_check(struct sta_info *sta)
{
struct ieee80211_sub_if_data *sdata = sta->sdata;
@@ -450,50 +411,15 @@ static int sta_info_insert_check(struct
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_rx(sdata, sta->sta.addr)) {
- spin_unlock_irqrestore(&local->sta_lock, flags);
- rcu_read_lock();
- return -EEXIST;
- }
-
- local->num_sta++;
- local->sta_generation++;
- smp_mb();
- sta_info_hash_add(local, sta);
-
- list_add_tail(&sta->list, &local->sta_pending_list);
-
- 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);
-#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
-
- ieee80211_queue_work(&local->hw, &local->sta_finish_work);
-
- 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)
+static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU)
{
struct ieee80211_local *local = sta->local;
struct ieee80211_sub_if_data *sdata = sta->sdata;
- unsigned long flags;
struct sta_info *exist_sta;
bool dummy_reinsert = false;
int err = 0;
@@ -501,19 +427,8 @@ static int sta_info_insert_non_ibss(stru
lockdep_assert_held(&local->sta_mtx);
/*
- * On first glance, this will look racy, because the code
- * 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.
- */
-
- spin_lock_irqsave(&local->sta_lock, flags);
- /*
* check if STA exists already.
- * only accept a scenario of a second call to sta_info_insert_non_ibss
+ * only accept a scenario of a second call to sta_info_insert_finish
* with a dummy station entry that was inserted earlier
* in that case - assume that the dummy station flag should
* be removed.
@@ -523,15 +438,12 @@ static int sta_info_insert_non_ibss(stru
if (exist_sta == sta && sta->dummy) {
dummy_reinsert = true;
} else {
- spin_unlock_irqrestore(&local->sta_lock, flags);
mutex_unlock(&local->sta_mtx);
rcu_read_lock();
return -EEXIST;
}
}
- spin_unlock_irqrestore(&local->sta_lock, flags);
-
err = sta_info_finish_insert(sta, false, dummy_reinsert);
if (err) {
mutex_unlock(&local->sta_mtx);
@@ -557,42 +469,19 @@ static int sta_info_insert_non_ibss(stru
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;
+ might_sleep();
+
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);
+ err = sta_info_insert_finish(sta);
if (err)
goto out_free;
@@ -626,7 +515,7 @@ int sta_info_reinsert(struct sta_info *s
might_sleep();
- err = sta_info_insert_non_ibss(sta);
+ err = sta_info_insert_finish(sta);
rcu_read_unlock();
return err;
}
@@ -713,7 +602,7 @@ void sta_info_recalc_tim(struct sta_info
}
done:
- spin_lock_irqsave(&local->sta_lock, flags);
+ spin_lock_irqsave(&local->tim_lock, flags);
if (indicate_tim)
__bss_tim_set(bss, sta->sta.aid);
@@ -726,7 +615,7 @@ void sta_info_recalc_tim(struct sta_info
local->tim_in_locked_section = false;
}
- spin_unlock_irqrestore(&local->sta_lock, flags);
+ spin_unlock_irqrestore(&local->tim_lock, flags);
}
static bool sta_info_buffer_expired(struct sta_info *sta, struct sk_buff *skb)
@@ -850,7 +739,6 @@ static int __must_check __sta_info_destr
{
struct ieee80211_local *local;
struct ieee80211_sub_if_data *sdata;
- unsigned long flags;
int ret, i, ac;
might_sleep();
@@ -870,15 +758,12 @@ static int __must_check __sta_info_destr
set_sta_flag(sta, WLAN_STA_BLOCK_BA);
ieee80211_sta_tear_down_BA_sessions(sta, true);
- spin_lock_irqsave(&local->sta_lock, flags);
ret = sta_info_hash_del(local, sta);
- /* this might still be the pending list ... which is fine */
- if (!ret)
- list_del(&sta->list);
- spin_unlock_irqrestore(&local->sta_lock, flags);
if (ret)
return ret;
+ list_del(&sta->list);
+
mutex_lock(&local->key_mtx);
for (i = 0; i < NUM_DEFAULT_KEYS; i++)
__ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]));
@@ -1009,11 +894,9 @@ static void sta_info_cleanup(unsigned lo
void sta_info_init(struct ieee80211_local *local)
{
- spin_lock_init(&local->sta_lock);
+ spin_lock_init(&local->tim_lock);
mutex_init(&local->sta_mtx);
INIT_LIST_HEAD(&local->sta_list);
- INIT_LIST_HEAD(&local->sta_pending_list);
- INIT_WORK(&local->sta_finish_work, sta_info_finish_work);
setup_timer(&local->sta_cleanup, sta_info_cleanup,
(unsigned long)local);
@@ -1042,9 +925,6 @@ int sta_info_flush(struct ieee80211_loca
might_sleep();
mutex_lock(&local->sta_mtx);
-
- sta_info_finish_pending(local);
-
list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
if (!sdata || sdata == sta->sdata)
WARN_ON(__sta_info_destroy(sta));
--- a/net/mac80211/ieee80211_i.h 2011-12-14 13:57:54.000000000 +0100
+++ b/net/mac80211/ieee80211_i.h 2011-12-14 14:03:28.000000000 +0100
@@ -855,18 +855,15 @@ struct ieee80211_local {
/* Station data */
/*
- * The mutex only protects the list and counter,
- * reads are done in RCU.
- * Additionally, the lock protects the hash table,
- * the pending list and each BSS's TIM bitmap.
+ * The mutex only protects the list, hash table and
+ * counter, reads are done with RCU.
*/
struct mutex sta_mtx;
- spinlock_t sta_lock;
+ spinlock_t tim_lock;
unsigned long num_sta;
- struct list_head sta_list, sta_pending_list;
+ struct list_head sta_list;
struct sta_info __rcu *sta_hash[STA_HASH_SIZE];
struct timer_list sta_cleanup;
- struct work_struct sta_finish_work;
int sta_generation;
struct sk_buff_head pending[IEEE80211_MAX_QUEUES];
--- a/net/mac80211/tx.c 2011-12-14 13:57:54.000000000 +0100
+++ b/net/mac80211/tx.c 2011-12-14 14:03:28.000000000 +0100
@@ -2333,9 +2333,9 @@ struct sk_buff *ieee80211_beacon_get_tim
} else {
unsigned long flags;
- spin_lock_irqsave(&local->sta_lock, flags);
+ spin_lock_irqsave(&local->tim_lock, flags);
ieee80211_beacon_add_tim(ap, skb, beacon);
- spin_unlock_irqrestore(&local->sta_lock, flags);
+ spin_unlock_irqrestore(&local->tim_lock, flags);
}
if (tim_offset)
--
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