staging: comedi: comedi_fops: always clear events

`comedi_event()` is called from low-level drivers to handle asynchronous
command event flags that are stored in `s->async->events` for subdevice
`s`.  It normally clears the event flags as well.  As a safety check, it
does nothing if no asynchronous command is running, but it leaves
`s->async->events` unchanged in this case.  For additional safety,
change it to always clear the event flags to avoid leaving stale event
flags set when another asynchronous command is set up.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 999e7d0..68ced20 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2648,18 +2648,20 @@ void comedi_event(struct comedi_device *dev, struct comedi_subdevice *s)
        struct comedi_async *async = s->async;
        unsigned runflags = 0;
        unsigned runflags_mask = 0;
+       unsigned int events = async->events;
 
+       async->events = 0;
        if (!comedi_is_subdevice_running(s))
                return;
 
-       if (async->events & COMEDI_CB_CANCEL_MASK)
+       if (events & COMEDI_CB_CANCEL_MASK)
                runflags_mask |= COMEDI_SRF_RUNNING;
 
        /*
         * Remember if an error event has occurred, so an error
         * can be returned the next time the user does a read().
         */
-       if (async->events & COMEDI_CB_ERROR_MASK) {
+       if (events & COMEDI_CB_ERROR_MASK) {
                runflags_mask |= COMEDI_SRF_ERROR;
                runflags |= COMEDI_SRF_ERROR;
        }
@@ -2671,14 +2673,13 @@ void comedi_event(struct comedi_device *dev, struct comedi_subdevice *s)
                comedi_update_subdevice_runflags(s, runflags_mask, runflags);
        }
 
-       if (async->cb_mask & async->events) {
+       if (async->cb_mask & events) {
                wake_up_interruptible(&async->wait_head);
                if (s->subdev_flags & SDF_CMD_READ)
                        kill_fasync(&dev->async_queue, SIGIO, POLL_IN);
                if (s->subdev_flags & SDF_CMD_WRITE)
                        kill_fasync(&dev->async_queue, SIGIO, POLL_OUT);
        }
-       async->events = 0;
 }
 EXPORT_SYMBOL_GPL(comedi_event);