Re: Null Pointer BUG in uhci_hcd

Alan Stern
2009-07-07T15:10:43Z

On Tue, 7 Jul 2009, Oliver Neukum wrote:

> Am Dienstag, 7. Juli 2009 11:13:01 schrieb Jiri Kosina:
> > [ adding linux-usb to CC ]
> >
> > On Sun, 5 Jul 2009, Michael S. Zick wrote:
> > > Anyone with suggestions about this one?
>
> Looks like we should test for presence before we switch off
> autosuspend for khubd. Please test this diagnostic patch if this is
> repeatable.

That patch won't fix the problem. This issue is not that hdev is NULL;
the problem is that the hub driver isn't bound to hdev and as a result,
the hdev_to_hub routine fails.

This patch may work better.

Alan Stern

Index: usb-2.6/drivers/usb/core/hub.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/hub.c
+++ usb-2.6/drivers/usb/core/hub.c
@@ -163,8 +163,10 @@ static inline char *portspeed(int portst
}

/* Note that hdev or one of its children must be locked! */
-static inline struct usb_hub *hdev_to_hub(struct usb_device *hdev)
+static struct usb_hub *hdev_to_hub(struct usb_device *hdev)
{
+ if (!hdev || !hdev->actconfig)
+ return NULL;
return usb_get_intfdata(hdev->actconfig->interface[0]);
}

@@ -385,8 +387,10 @@ static void kick_khubd(struct usb_hub *h

void usb_kick_khubd(struct usb_device *hdev)
{
- /* FIXME: What if hdev isn't bound to the hub driver? */
- kick_khubd(hdev_to_hub(hdev));
+ struct usb_hub *hub = hdev_to_hub(hdev);
+
+ if (hub)
+ kick_khubd(hub);
}