2009-05-15 10:36:22

by Karl Hiramoto

Subject: [PATCH] hostapd: nl80211 retry creating a interface if it fails the first time.

If hostapd segfaults, or is killed with -9, or the interface already exists, when the interface is created, it will fail.

A normal case with hostapd runing:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:01:02:03:04:05 brd ff:ff:ff:ff:ff:ff
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 8a:cb:b3:76:b0:5d brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 100
link/ether d6:07:19:ee:b5:8d brd ff:ff:ff:ff:ff:ff
5: wmaster0: <UP,LOWER_UP> mtu 0 qdisc pfifo_fast qlen 1000
link/ieee802.11 00:0e:8e:15:6e:0b brd 00:00:00:00:00:00
7: wlan0_0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:13:01:01:08:0a brd ff:ff:ff:ff:ff:ff
9: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether 00:13:01:01:08:0a brd ff:ff:ff:ff:ff:ff
11: br1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether 00:01:02:03:04:05 brd ff:ff:ff:ff:ff:ff
14: mon.wlan0_0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/[803] 00:0e:8e:15:6e:0b brd ff:ff:ff:ff:ff:ff
15: wlan0_1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:13:01:01:08:0b brd ff:ff:ff:ff:ff:ff

Then rudely kill hostapd.

Mon interface still exists, as well as second ap created by hostapd

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:01:02:03:04:05 brd ff:ff:ff:ff:ff:ff
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 8a:cb:b3:76:b0:5d brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 100
link/ether d6:07:19:ee:b5:8d brd ff:ff:ff:ff:ff:ff
5: wmaster0: <UP,LOWER_UP> mtu 0 qdisc pfifo_fast qlen 1000
link/ieee802.11 00:0e:8e:15:6e:0b brd 00:00:00:00:00:00
7: wlan0_0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:13:01:01:08:0a brd ff:ff:ff:ff:ff:ff
9: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether 00:13:01:01:08:0a brd ff:ff:ff:ff:ff:ff
11: br1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
link/ether 00:01:02:03:04:05 brd ff:ff:ff:ff:ff:ff
14: mon.wlan0_0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/[803] 00:0e:8e:15:6e:0b brd ff:ff:ff:ff:ff:ff
15: wlan0_1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:13:01:01:08:0b brd ff:ff:ff:ff:ff:ff

Hostapd will fail on startup.

Configuration file: /tmp/hostapd/hostapd.conf
Failed to create interface mon.wlan0_0.
Using interface wlan0_0 with hwaddr 00:13:01:01:08:0a and ssid 'IG_0405_LAN'
Failed to set beacon head/tail or DTIM period
Failed to create interface wlan0_1.

This patch solves this issue.

Signed-off-by: Karl Hiramoto <[email protected]>
---
src/drivers/driver_nl80211.c | 23 ++++++++++++++++++++++-
1 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 79c7889..6e5f48e 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -2468,7 +2468,7 @@ static void nl80211_remove_iface(struct wpa_driver_nl80211_data *drv,
}


-static int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,
+static int nl80211_create_iface_once(struct wpa_driver_nl80211_data *drv,
const char *ifname, enum nl80211_iftype iftype,
const u8 *addr)
{
@@ -2529,6 +2529,27 @@ static int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,

return ifidx;
}
+static int nl80211_create_iface(struct wpa_driver_nl80211_data *drv,
+ const char *ifname, enum nl80211_iftype iftype,
+ const u8 *addr)
+{
+ int ret;
+
+ ret = nl80211_create_iface_once(drv, ifname, iftype, addr);
+
+ /*if error occured and iterface already exists */
+ if (ret < 0 && if_nametoindex(ifname)) {
+ wpa_printf(MSG_INFO, "Retrying to create %s.", ifname);
+
+ /*remove iface that was already there. */
+ nl80211_remove_iface(drv, if_nametoindex(ifname));
+
+ /* retry to create iface*/
+ ret = nl80211_create_iface_once(drv, ifname, iftype, addr);
+ }
+
+ return ret;
+}

#endif /* CONFIG_AP || HOSTAPD */

--
1.6.0.6

2009-05-29 19:05:45

by Jouni Malinen

Subject: Re: [PATCH] hostapd: nl80211 retry creating a interface if it fails the first time.

On Fri, May 15, 2009 at 12:36:08PM +0200, Karl Hiramoto wrote:
> If hostapd segfaults, or is killed with -9, or the interface already exists, when the interface is created, it will fail.

> This patch solves this issue.

Thanks, applied with a change to do this only on ENFILE errors which is
the errno used by __dev_alloc_name() in this particular case where
mac80211 fails to add an interface due to the interface being there
already.

--
Jouni Malinen PGP id EFC895FA