From zaitcev@redhat.com Thu Jan 5 00:17:16 2006 Date: Thu, 5 Jan 2006 00:14:02 -0800 From: Pete Zaitcev To: greg@kroah.com Subject: USB: ub 04 Loss of timer and a hang Message-Id: <20060105001402.0a1f019d.zaitcev@redhat.com> If SCSI commands are submitted while other commands are still processed, the dispatch loop turns, and we stop the work_timer. Then, if URB fails to complete, ub hangs until the device is unplugged. This does not happen often, becase we only allow one SCSI command per block device, but does happen (on multi-LUN devices, for example). The fix is to stop timer only when we actually going to change the state. The nicest code would be to have the timer stopped in URB callback, but this is impossible, because it can be called from inside a timer, through the urb_unlink. Then we get BUG in timer.c:cascade(). So, we do it a little dirtier. Signed-off-by: Pete Zaitcev Signed-off-by: Greg Kroah-Hartman --- drivers/block/ub.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- gregkh-2.6.orig/drivers/block/ub.c +++ gregkh-2.6/drivers/block/ub.c @@ -1106,7 +1106,8 @@ static void ub_urb_timeout(unsigned long unsigned long flags; spin_lock_irqsave(sc->lock, flags); - usb_unlink_urb(&sc->work_urb); + if (!ub_is_completed(&sc->work_done)) + usb_unlink_urb(&sc->work_urb); spin_unlock_irqrestore(sc->lock, flags); } @@ -1131,7 +1132,6 @@ static void ub_scsi_action(unsigned long unsigned long flags; spin_lock_irqsave(sc->lock, flags); - del_timer(&sc->work_timer); ub_scsi_dispatch(sc); spin_unlock_irqrestore(sc->lock, flags); } @@ -1155,6 +1155,7 @@ static void ub_scsi_dispatch(struct ub_d } else { if (!ub_is_completed(&sc->work_done)) break; + del_timer(&sc->work_timer); ub_scsi_urb_compl(sc, cmd); } }