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xhci: Remove TDs from TD lists when URBs are canceled.

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When a driver tries to cancel an URB, and the host controller is dying,
xhci_urb_dequeue will giveback the URB without removing the xhci_tds
that comprise that URB from the td_list or the cancelled_td_list.  This
can cause a race condition between the driver calling URB dequeue and
the stop endpoint command watchdog timer.

If the timer fires on a dying host, and a driver attempts to resubmit
while the watchdog timer has dropped the xhci->lock to giveback a
cancelled URB, URBs may be given back by the xhci_urb_dequeue() function.
At that point, the URB's priv pointer will be freed and set to NULL, but
the TDs will remain on the td_list.  This will cause an oops in
xhci_giveback_urb_in_irq() when the watchdog timer attempts to loop
through the endpoints' td_lists, giving back killed URBs.

Make sure that xhci_urb_dequeue() removes TDs from the TD lists and
canceled TD lists before it gives back the URB.

This patch should be backported to kernels as old as 2.6.36.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Andiry Xu <andiry.xu@amd.com>
Cc: stable@kernel.org
This commit is contained in:
Sarah Sharp 2011-08-02 15:43:40 -07:00
parent 522989a27c
commit 585df1d90c
2 changed files with 15 additions and 8 deletions
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7
drivers/usb/host/xhci.c
View file

@ -1252,6 +1252,13 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_HALTED)) {
xhci_dbg(xhci, "HW died, freeing TD.\n");
urb_priv = urb->hcpriv;
for (i = urb_priv->td_cnt; i < urb_priv->length; i++) {
td = urb_priv->td[i];
if (!list_empty(&td->td_list))
list_del_init(&td->td_list);
if (!list_empty(&td->cancelled_td_list))
list_del_init(&td->cancelled_td_list);
}
usb_hcd_unlink_urb_from_ep(hcd, urb);
spin_unlock_irqrestore(&xhci->lock, flags);