On Fri, 12 Jun 2009, Julie Zhu wrote:
> > > Is this a bug?
> >
> > Probably not. The periodic schedule should be enabled as long as any
> > periodic URBs are queued. The fact that they are addressed to a
> device
> > which has been unplugged doesn't matter -- usb_disconnect() will
> unlink
> > the remaining URBs for the unplugged device quickly enough.
> >
> > Alan Stern
> >
>
> Well, it does happen, and printks show the path of periodic schedule
> disable/enable/disable.
Sure. It happens, but it's not a bug. The same thing would happen if
you queued a bunch of interrupt URBs for a device and then unlinked the
first one, without unplugging anything.
> Can you point me to where qh->qtd_list is
> updated?
It is updated in qh_completions(). There are two widely separated
regions in the source code:
list_for_each_safe (entry, tmp, &qh->qtd_list) {
struct ehci_qtd *qtd;
...
qtd = list_entry (entry, struct ehci_qtd, qtd_list);
and then much later:
/* remove qtd; it's recycled after possible urb completion */
list_del (&qtd->qtd_list);
Alan Stern
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