[48/99] mac80211: check interface is down before type change

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>

commit c1f9a764cf47686b1f5a0cf87ada68d90056136a upstream.

For some strange reason the netif_running() check
ended up after the actual type change instead of
before, potentially causing all kinds of problems
if the interface is up while changing the type;
one of the problems manifests itself as a warning:

WARNING: at net/mac80211/iface.c:651 ieee80211_teardown_sdata+0xda/0x1a0 [mac80211]()
Hardware name: Aspire one
Pid: 2596, comm: wpa_supplicant Tainted: G        W  2.6.31-10-generic #32-Ubuntu
Call Trace:
 [] warn_slowpath_common+0x6d/0xa0
 [] warn_slowpath_null+0x15/0x20
 [] ieee80211_teardown_sdata+0xda/0x1a0 [mac80211]
 [] ieee80211_if_change_type+0x4a/0xc0 [mac80211]
 [] ieee80211_change_iface+0x61/0xa0 [mac80211]
 [] cfg80211_wext_siwmode+0xc7/0x120 [cfg80211]
 [] ioctl_standard_call+0x58/0xf0

(http://www.kerneloops.org/searchweek.php?search=ieee80211_teardown_sdata)

Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/mac80211/cfg.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -87,6 +87,9 @@ static int ieee80211_change_iface(struct
 	if (!dev)
 		return -ENODEV;
 
+	if (netif_running(dev))
+		return -EBUSY;
+
 	if (!nl80211_type_check(type))
 		return -EINVAL;
 
@@ -96,9 +99,6 @@ static int ieee80211_change_iface(struct
 	if (ret)
 		return ret;
 
-	if (netif_running(sdata->dev))
-		return -EBUSY;
-
 	if (ieee80211_vif_is_mesh(&sdata->vif) && params->mesh_id_len)
 		ieee80211_sdata_set_mesh_id(sdata,
 					    params->mesh_id_len,


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/