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USB: musb: host endpoint_disable() oops fixes

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The musb_h_disable() routine can oops in some cases:

 - It's not safe to read hep->hcpriv outside musb->lock,
   since it gets changed on completion IRQ paths.

 - The list iterators aren't safe to use in that way;
   just remove the first element while !list_empty(),
   so deletions on other code paths can't make trouble.

We need two "scrub the list" loops because only one branch
should touch hardware and advance the schedule.

[ dbrownell@users.sourceforge.net: massively simplify
  patch description; add key points as code comments ]

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Sergei Shtylyov 2009-02-21 15:31:01 -08:00 committed by Greg Kroah-Hartman
parent a2fd814e6a
commit dc61d238b8
1 changed files with 26 additions and 10 deletions
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36
drivers/usb/musb/musb_host.c
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@ -2103,15 +2103,16 @@ musb_h_disable(struct usb_hcd *hcd, struct usb_host_endpoint *hep)
unsigned long flags;
struct musb *musb = hcd_to_musb(hcd);
u8 is_in = epnum & USB_DIR_IN;
struct musb_qh *qh = hep->hcpriv;
struct urb *urb, *tmp;
struct musb_qh *qh;
struct urb *urb;
struct list_head *sched;
if (!qh)
return;
spin_lock_irqsave(&musb->lock, flags);
qh = hep->hcpriv;
if (qh == NULL)
goto exit;
switch (qh->type) {
case USB_ENDPOINT_XFER_CONTROL:
sched = &musb->control;
@ -2145,13 +2146,28 @@ musb_h_disable(struct usb_hcd *hcd, struct usb_host_endpoint *hep)
/* cleanup */
musb_cleanup_urb(urb, qh, urb->pipe & USB_DIR_IN);
} else
urb = NULL;
/* then just nuke all the others */
list_for_each_entry_safe_from(urb, tmp, &hep->urb_list, urb_list)
musb_giveback(qh, urb, -ESHUTDOWN);
/* Then nuke all the others ... and advance the
* queue on hw_ep (e.g. bulk ring) when we're done.
*/
while (!list_empty(&hep->urb_list)) {
urb = next_urb(qh);
urb->status = -ESHUTDOWN;
musb_advance_schedule(musb, urb, qh->hw_ep, is_in);
}
} else {
/* Just empty the queue; the hardware is busy with
* other transfers, and since !qh->is_ready nothing
* will activate any of these as it advances.
*/
while (!list_empty(&hep->urb_list))
__musb_giveback(musb, next_urb(qh), -ESHUTDOWN);
hep->hcpriv = NULL;
list_del(&qh->ring);
kfree(qh);
}
exit:
spin_unlock_irqrestore(&musb->lock, flags);
}