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/net/mac80211/rc80211_simple.c b/net/mac80211/rc80211_simple.c
index bcc541d..4f72fdc 100644
--- a/net/mac80211/rc80211_simple.c
+++ b/net/mac80211/rc80211_simple.c
@@ -40,7 +40,7 @@
int i = sta->txrate_idx;
int maxrate;
- sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+ sdata = sta->sdata;
if (sdata->bss && sdata->bss->force_unicast_rateidx > -1) {
/* forced unicast rate - do not change STA rate */
return;
@@ -70,7 +70,7 @@
struct ieee80211_supported_band *sband;
int i = sta->txrate_idx;
- sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+ sdata = sta->sdata;
if (sdata->bss && sdata->bss->force_unicast_rateidx > -1) {
/* forced unicast rate - do not change STA rate */
return;
@@ -118,10 +118,12 @@
struct sta_info *sta;
struct sta_rate_control *srctrl;
+ rcu_read_lock();
+
sta = sta_info_get(local, hdr->addr1);
if (!sta)
- return;
+ goto unlock;
srctrl = sta->rate_ctrl_priv;
srctrl->tx_num_xmit++;
@@ -191,7 +193,8 @@
}
}
- sta_info_put(sta);
+ unlock:
+ rcu_read_unlock();
}
@@ -208,6 +211,8 @@
int rateidx;
u16 fc;
+ rcu_read_lock();
+
sta = sta_info_get(local, hdr->addr1);
/* Send management frames and broadcast/multicast data using lowest
@@ -216,8 +221,7 @@
if ((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA ||
is_multicast_ether_addr(hdr->addr1) || !sta) {
sel->rate = rate_lowest(local, sband, sta);
- if (sta)
- sta_info_put(sta);
+ rcu_read_unlock();
return;
}
@@ -233,7 +237,7 @@
sta->last_txrate_idx = rateidx;
- sta_info_put(sta);
+ rcu_read_unlock();
sel->rate = &sband->bitrates[rateidx];
}