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mac80211: atomically check whether STA exists already

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When a STA structure is added, it is often checked whether it
already exists before adding it. This, however, isn't done
atomically so there is a race condition that could lead to two
STA structures being added with the same MAC address. This
patch changes sta_info_add() to return an ERR_PTR in case
of failure and adds the failure mode -EEXIST when the STA
already exists.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Johannes Berg
2008-02-21 14:09:30 +01:00
committed by John W. Linville
parent d46e144b65
commit 43ba7e958f
5 changed files with 39 additions and 30 deletions
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11
net/mac80211/cfg.c
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@@ -562,13 +562,6 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
if (!netif_running(dev))
return -ENETDOWN;
/* XXX: get sta belonging to dev */
sta = sta_info_get(local, mac);
if (sta) {
sta_info_put(sta);
return -EEXIST;
}
if (params->vlan) {
sdata = IEEE80211_DEV_TO_SUB_IF(params->vlan);
@@ -579,8 +572,8 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
sta = sta_info_add(local, dev, mac, GFP_KERNEL);
if (!sta)
return -ENOMEM;
if (IS_ERR(sta))
return PTR_ERR(sta);
sta->dev = sdata->dev;
if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN ||