On Thu, 26 Dec 2013, Du, ChangbinX wrote:
> I can reproduce issue by adding a delay just after usb_set_intfdata(intf,
> NULL)
> (echo -1 > bConfigurationValue to trigger hub_dissconnect())without your
> patch.
>
> After patch applied, cannot reproduce and didn't found any other issue. Patch
> works well.
>
> Alan, need I update patch to v2 or you will do it?
Changbin, after looking more closely I realized there was a second
aspect to this race: recursively_mark_NOTATTACHED uses hub->ports[i]
while hub_disconnect removes the port devices. You ought to be
able to cause an oops by inserting a delay just after the loop where
usb_hub_remove_port_device is called.
The updated patch below should fix both problems. Can you test it?
Alan Stern
Index: usb-3.13/drivers/usb/core/hub.c
===================================================================
--- usb-3.13.orig/drivers/usb/core/hub.c
+++ usb-3.13/drivers/usb/core/hub.c
@@ -1607,7 +1607,7 @@ static void hub_disconnect(struct usb_in
{
struct usb_hub *hub = usb_get_intfdata(intf);
struct usb_device *hdev = interface_to_usbdev(intf);
- int i;
+ int port1;
/* Take the hub off the event list and don't let it be added again */
spin_lock_irq(&hub_event_lock);
@@ -1622,11 +1622,15 @@ static void hub_disconnect(struct usb_in
hub->error = 0;
hub_quiesce(hub, HUB_DISCONNECT);
- usb_set_intfdata (intf, NULL);
+ /* Avoid races with recursively_mark_NOTATTACHED() */
+ spin_lock_irq(&device_state_lock);
+ port1 = hdev->maxchild;
+ hdev->maxchild = 0;
+ usb_set_intfdata(intf, NULL);
+ spin_unlock_irq(&device_state_lock);
- for (i = 0; i < hdev->maxchild; i++)
- usb_hub_remove_port_device(hub, i + 1);
- hub->hdev->maxchild = 0;
+ for (; port1 > 0; --port1)
+ usb_hub_remove_port_device(hub, port1);
if (hub->hdev->speed == USB_SPEED_HIGH)
highspeed_hubs--;
--
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