On 9/5/24 15:46, Oliver Neukum wrote:
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
drivers/net/usb/usbnet.c | 37 ++++++++++++++++++++++++++++--------- include/linux/usb/usbnet.h | 17 +++++++++++++++++ 2 files changed, 45 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))
} } else { netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");__usbnet_queue_skb(&dev->rxq, skb, rx_start);
@@ -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);
I guess you do the shutdown twice because a running tasklet or timer could re-schedule the others? If so, what prevent the rescheduling to happen in the 2nd iteration? why can't you add usbnet_going_away() checks on tasklet and timer reschedule point?
Thanks,
Paolo