[WIRELESS] cfg80211: Fix locking in wiphy_new.

This patch fixes the locking in wiphy new. Ingo Oeser
<netdev@axxeo.de> noticed that locking in the error case was wrong and
also suggested this fix.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 6 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 532e1e09e02..24a21add0ba 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -53,21 +53,25 @@ struct wiphy *wiphy_new(struct cfg80211_ops *ops, int sizeof_priv)
 
         mutex_lock(&cfg80211_drv_mutex);
 
-        if (unlikely(wiphy_counter<0)) {
+        drv->idx = wiphy_counter;
+
+        /* now increase counter for the next device unless
+         * it has wrapped previously */
+        if (wiphy_counter >= 0)
+                wiphy_counter++;
+
+        mutex_unlock(&cfg80211_drv_mutex);
+
+        if (unlikely(drv->idx < 0)) {
                 /* ugh, wrapped! */
                 kfree(drv);
                 return NULL;
         }
-        drv->idx = wiphy_counter;
 
         /* give it a proper name */
         snprintf(drv->wiphy.dev.bus_id, BUS_ID_SIZE,
                  PHY_NAME "%d", drv->idx);
 
-        /* now increase counter for the next time */
-        wiphy_counter++;
-        mutex_unlock(&cfg80211_drv_mutex);
-
         mutex_init(&drv->mtx);
         mutex_init(&drv->devlist_mtx);
         INIT_LIST_HEAD(&drv->netdev_list);