netdev - [PATCH wireless-dev, net-2.6.22] cfg80211: fix locking in wiphy

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Date:	Thu, 26 Apr 2007 15:14:22 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Ingo Oeser <netdev@...eo.de>
Cc:	"John W. Linville" <linville@...driver.com>, davem@...emloft.net,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH wireless-dev, net-2.6.22] cfg80211: fix locking in wiphy_new

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

Signed-off-by: Johannes Berg <johannes@...solutions.net>

---
As with other patches, this is diffed against wireless-dev but applies
against net-2.6.22 (or is that net-2.6 now?) with some offset (but no
fuzz.)

---
 net/wireless/core.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- wireless-dev.orig/net/wireless/core.c	2007-04-26 15:01:15.623251869 +0200
+++ wireless-dev/net/wireless/core.c	2007-04-26 15:07:27.933251869 +0200
@@ -189,21 +189,25 @@ struct wiphy *wiphy_new(struct cfg80211_
 
 	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);


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