On Wed, 4 Aug 2010, Oliver Neukum wrote:
> > @@ -749,20 +756,11 @@ EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
> > void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
> > {
> > struct urb *victim;
> > - unsigned long flags;
> >
> > - spin_lock_irqsave(&anchor->lock, flags);
> > - while (!list_empty(&anchor->urb_list)) {
> > - victim = list_entry(anchor->urb_list.prev, struct urb,
> > - anchor_list);
> > - usb_get_urb(victim);
> > - spin_unlock_irqrestore(&anchor->lock, flags);
> > - /* this will unanchor the URB */
> > + while ((victim = usb_get_from_anchor(anchor)) != NULL) {
> > usb_unlink_urb(victim);
> > usb_put_urb(victim);
> > - spin_lock_irqsave(&anchor->lock, flags);
> > }
> > - spin_unlock_irqrestore(&anchor->lock, flags);
>
> This was written in the slightly convoluted manner out of fear that HCDs
> would call right back into usb_hcd_giveback_urb() which would unanchor
> the URB.
>
> Alan, do we have HCD drivers that do that?
Yes, under some circumstances. But it's not an issue here; the unlink
call happens outside the scope of the anchor spinlock.
Alan Stern
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