The work can submit URBs and the URBs can schedule the work. This cycle needs to be broken, when a device is to be stopped. Use a flag to do so. This is a design issue as old as the driver.

Signed-off-by: Oliver Neukum oneukum@suse.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") CC: stable@vger.kernel.org ---

v2: fix PM reference issue v3: drop unneeded memory ordering primitives

drivers/net/usb/usbnet.c | 37 ++++++++++++++++++++++++++++--------- include/linux/usb/usbnet.h | 15 +++++++++++++++ 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 18eb5ba436df..2506aa8c603e 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -464,10 +464,15 @@ static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb, void usbnet_defer_kevent (struct usbnet *dev, int work) { set_bit (work, &dev->flags); - if (!schedule_work (&dev->kevent)) - netdev_dbg(dev->net, "kevent %s may have been dropped\n", usbnet_event_names[work]); - else - netdev_dbg(dev->net, "kevent %s scheduled\n", usbnet_event_names[work]); + if (!usbnet_going_away(dev)) { + if (!schedule_work(&dev->kevent)) + netdev_dbg(dev->net, + "kevent %s may have been dropped\n", + usbnet_event_names[work]); + else + netdev_dbg(dev->net, + "kevent %s scheduled\n", usbnet_event_names[work]); + } } EXPORT_SYMBOL_GPL(usbnet_defer_kevent);

@@ -535,7 +540,8 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags) tasklet_schedule (&dev->bh); break; case 0: - __usbnet_queue_skb(&dev->rxq, skb, rx_start); + if (!usbnet_going_away(dev)) + __usbnet_queue_skb(&dev->rxq, skb, rx_start); } } else { netif_dbg(dev, ifdown, dev->net, "rx: stopped\n"); @@ -843,9 +849,18 @@ int usbnet_stop (struct net_device *net)

/* deferred work (timer, softirq, task) must also stop */ dev->flags = 0; - del_timer_sync (&dev->delay); - tasklet_kill (&dev->bh); + del_timer_sync(&dev->delay); + tasklet_kill(&dev->bh); cancel_work_sync(&dev->kevent); + + /* We have cyclic dependencies. Those calls are needed + * to break a cycle. We cannot fall into the gaps because + * we have a flag + */ + tasklet_kill(&dev->bh); + del_timer_sync(&dev->delay); + cancel_work_sync(&dev->kevent); + if (!pm) usb_autopm_put_interface(dev->intf);

@@ -1171,7 +1186,8 @@ usbnet_deferred_kevent (struct work_struct *work) status); } else { clear_bit (EVENT_RX_HALT, &dev->flags); - tasklet_schedule (&dev->bh); + if (!usbnet_going_away(dev)) + tasklet_schedule(&dev->bh); } }

@@ -1196,7 +1212,8 @@ usbnet_deferred_kevent (struct work_struct *work) usb_autopm_put_interface(dev->intf); fail_lowmem: if (resched) - tasklet_schedule (&dev->bh); + if (!usbnet_going_away(dev)) + tasklet_schedule(&dev->bh); } }

@@ -1559,6 +1576,7 @@ static void usbnet_bh (struct timer_list *t) } else if (netif_running (dev->net) && netif_device_present (dev->net) && netif_carrier_ok(dev->net) && + !usbnet_going_away(dev) && !timer_pending(&dev->delay) && !test_bit(EVENT_RX_PAUSED, &dev->flags) && !test_bit(EVENT_RX_HALT, &dev->flags)) { @@ -1606,6 +1624,7 @@ void usbnet_disconnect (struct usb_interface *intf) usb_set_intfdata(intf, NULL); if (!dev) return; + usbnet_mark_going_away(dev);

xdev = interface_to_usbdev (intf);

diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index 9f08a584d707..0b9f1e598e3a 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -76,8 +76,23 @@ struct usbnet { # define EVENT_LINK_CHANGE 11 # define EVENT_SET_RX_MODE 12 # define EVENT_NO_IP_ALIGN 13 +/* This one is special, as it indicates that the device is going away + * there are cyclic dependencies between tasklet, timer and bh + * that must be broken + */ +# define EVENT_UNPLUG 31 };

+static inline bool usbnet_going_away(struct usbnet *ubn) +{ + return test_bit(EVENT_UNPLUG, &ubn->flags); +} + +static inline void usbnet_mark_going_away(struct usbnet *ubn) +{ + set_bit(EVENT_UNPLUG, &ubn->flags); +} + static inline struct usb_driver *driver_of(struct usb_interface *intf) { return to_usb_driver(intf->dev.driver);