tree 458173b98580754a4ea5b73f2be5c11da90c1048
parent 5e5c860400ef1307e3d87aebd5ec8a35b078ca51
author Daniel Mack <zonque@gmail.com> 1313314276 +0200
committer Greg Kroah-Hartman <gregkh@suse.de> 1314649749 -0700

ALSA: snd_usb_caiaq: track submitted output urbs

commit da6094ea7d3c2295473d8f5134279307255d6ebf upstream.

The snd_usb_caiaq driver currently assumes that output urbs are serviced
in time and doesn't track when and whether they are given back by the
USB core. That usually works fine, but due to temporary limitations of
the XHCI stack, we faced that urbs were submitted more than once with
this approach.

As it's no good practice to fire and forget urbs anyway, this patch
introduces a proper bit mask to track which requests have been submitted
and given back.

That alone however doesn't make the driver work in case the host
controller is broken and doesn't give back urbs at all, and the output
stream will stop once all pre-allocated output urbs are consumed. But
it does prevent crashes of the controller stack in such cases.

See http://bugzilla.kernel.org/show_bug.cgi?id=40702 for more details.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-and-tested-by: Matej Laitl <matej@laitl.cz>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>