WAN: flush tx_queue in hdlc_ppp to prevent panic on rmmod hw_driver.

tx_queue is used as a temporary queue when not allowed to queue skb
directly to the hw device driver (which may sleep). Most paths flush
it before returning, but ppp_start() currently cannot. Make sure we
don't leave skbs pointing to a non-existent device.

Thanks to Michael Barkowski for reporting this problem.

Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c
index b9b9d6b..941f053 100644 (file)
--- a/drivers/net/wan/hdlc_ppp.c
+++ b/drivers/net/wan/hdlc_ppp.c
@@ -628,9 +628,15 @@ static void ppp_stop(struct net_device *dev)
        ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
 }
 
+static void ppp_close(struct net_device *dev)
+{
+       ppp_tx_flush();
+}
+
 static struct hdlc_proto proto = {
        .start          = ppp_start,
        .stop           = ppp_stop,
+       .close          = ppp_close,
        .type_trans     = ppp_type_trans,
        .ioctl          = ppp_ioctl,
        .netif_rx       = ppp_rx,