Re: [RFT PATCH] xhci: Fix handling timeouted commands on hosts in weird states.

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, May 12, 2016 at 02:07:41PM +0300, Mathias Nyman wrote:
> If commands timeout we mark them for abortion, then stop the command
> ring, and turn the commands to no-ops and finally restart the command
> ring.
> 
> If the host is working properly the no-op commands will finish and
> pending completions are called.
> If we notice the host is failing driver clears the command ring and
> completes, deletes and frees all pending commands.
> 
> There are two separate cases reported where host is believed to work
> properly but is not. In the first case we successfully stop the ring
> but no abort or stop commnand ring event is ever sent and host locks up.
> 
> The second case is if a host is removed, command times out and driver
> believes the ring is stopped, and assumes it be restarted, but actually
> ends up timing out on the same command forever.
> If one of the pending commands has the xhci->mutex held it will block
> xhci_stop() in the remove codepath which otherwise would cleanup pending
> commands.
> 
> Add a check that clears all pending commands in case host is removed,
> or we are stuck timeouting on the same command. Also restart the
> command timeout timer when stopping the command ring to ensure we
> recive an ring stop/abort event.
> 
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>

Any reason why you just sent this to stable@ and not linux-usb@?