> On Apr 25, 2019, at 9:22 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Are you certain that those places with the very long timeouts are
> called with interrupts disabled?
I must admit, I have not reviewed all uses of the long xhci_handshakes. :) I have reviewed the following instance.
In usb/host/xhci-ring.c:xhci_abort_cmd_ring():
ret = xhci_handshake(&xhci->op_regs->cmd_ring,
CMD_RING_RUNNING, 0, 5 * 1000 * 1000);
if (ret < 0) {
xhci_err(xhci, "Abort failed to stop command ring: %d\n", ret);
xhci_halt(xhci);
xhci_hc_died(xhci);
return ret;
}
/*
* Writing the CMD_RING_ABORT bit should cause a cmd completion event,
* however on some host hw the CMD_RING_RUNNING bit is correctly cleared
* but the completion event in never sent. Wait 2 secs (arbitrary
* number) to handle those cases after negation of CMD_RING_RUNNING.
*/
spin_unlock_irqrestore(&xhci->lock, flags);
The spin_unlock occurs before the completion wait, so I assume that interrupts are disabled in the spin above. Also, the system does nothing during this period. No SSH, no serial, no log messages, etc.
Seth
