mac80211: RCU-ify STA info structure access
This makes access to the STA hash table/list use RCU to protect
against freeing of items. However, it's not a true RCU, the
copy step is missing: whenever somebody changes a STA item it
is simply updated. This is an existing race condition that is
now somewhat understandable.
This patch also fixes the race key freeing vs. STA destruction
by making sure that sta_info_destroy() is always called under
RTNL and frees the key.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-3945-rs.c b/drivers/net/wireless/iwlwifi/iwl-3945-rs.c
index a8223c4..c4bfba6 100644
--- a/drivers/net/wireless/iwlwifi/iwl-3945-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-3945-rs.c
@@ -471,10 +471,11 @@
return;
}
+ rcu_read_lock();
+
sta = sta_info_get(local, hdr->addr1);
if (!sta || !sta->rate_ctrl_priv) {
- if (sta)
- sta_info_put(sta);
+ rcu_read_unlock();
IWL_DEBUG_RATE("leave: No STA priv data to update!\n");
return;
}
@@ -547,7 +548,7 @@
spin_unlock_irqrestore(&rs_sta->lock, flags);
- sta_info_put(sta);
+ rcu_read_unlock();
IWL_DEBUG_RATE("leave\n");
@@ -658,6 +659,8 @@
IWL_DEBUG_RATE("enter\n");
+ rcu_read_lock();
+
sta = sta_info_get(local, hdr->addr1);
/* Send management frames and broadcast/multicast data using lowest
@@ -668,8 +671,7 @@
!sta || !sta->rate_ctrl_priv) {
IWL_DEBUG_RATE("leave: No STA priv data to update!\n");
sel->rate = rate_lowest(local, band, sta);
- if (sta)
- sta_info_put(sta);
+ rcu_read_unlock();
return;
}
@@ -811,7 +813,7 @@
else
sta->txrate_idx = sta->last_txrate_idx;
- sta_info_put(sta);
+ rcu_read_unlock();
IWL_DEBUG_RATE("leave: %d\n", index);
@@ -843,13 +845,15 @@
unsigned long now = jiffies;
u32 max_time = 0;
+ rcu_read_lock();
+
sta = sta_info_get(local, priv->stations[sta_id].sta.sta.addr);
if (!sta || !sta->rate_ctrl_priv) {
- if (sta) {
- sta_info_put(sta);
+ if (sta)
IWL_DEBUG_RATE("leave - no private rate data!\n");
- } else
+ else
IWL_DEBUG_RATE("leave - no station!\n");
+ rcu_read_unlock();
return sprintf(buf, "station %d not found\n", sta_id);
}
@@ -890,7 +894,7 @@
i = j;
}
spin_unlock_irqrestore(&rs_sta->lock, flags);
- sta_info_put(sta);
+ rcu_read_unlock();
/* Display the average rate of all samples taken.
*
@@ -927,11 +931,12 @@
return;
}
+ rcu_read_lock();
+
sta = sta_info_get(local, priv->stations[sta_id].sta.sta.addr);
if (!sta || !sta->rate_ctrl_priv) {
- if (sta)
- sta_info_put(sta);
IWL_DEBUG_RATE("leave - no private rate data!\n");
+ rcu_read_unlock();
return;
}
@@ -958,7 +963,7 @@
break;
}
- sta_info_put(sta);
+ rcu_read_unlock();
spin_unlock_irqrestore(&rs_sta->lock, flags);
rssi = priv->last_rx_rssi;