staging: comedi: usbdux: tidy up usbdux_ai_cmd()

Rename the local variable used for the private data pointer to the
comedi "norm".

Remove the unnecessary sanity check of the private data pointer. This
function can only be called is the private data was allocated during
the attach.

Tidy up the exit path using goto to ensure that the semaphore is
released.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/usbdux.c

@@ -882,85 +882,79 @@ static int usbdux_ai_inttrig(struct comedi_device *dev,
 
 static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 {
+	struct usbdux_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
-	unsigned int chan, range;
-	int i, ret;
-	struct usbdux_private *this_usbduxsub = dev->private;
-	int result;
-
-	if (!this_usbduxsub)
-		return -EFAULT;
+	int len = cmd->chanlist_len;
+	int ret = -EBUSY;
+	int i;
 
 	/* block other CPUs from starting an ai_cmd */
-	down(&this_usbduxsub->sem);
-	if (this_usbduxsub->ai_cmd_running) {
-		up(&this_usbduxsub->sem);
-		return -EBUSY;
-	}
+	down(&devpriv->sem);
+
+	if (devpriv->ai_cmd_running)
+		goto ai_cmd_exit;
+
 	/* set current channel of the running acquisition to zero */
 	s->async->cur_chan = 0;
 
-	this_usbduxsub->dux_commands[1] = cmd->chanlist_len;
-	for (i = 0; i < cmd->chanlist_len; ++i) {
-		chan = CR_CHAN(cmd->chanlist[i]);
-		range = CR_RANGE(cmd->chanlist[i]);
+	devpriv->dux_commands[1] = len;
+	for (i = 0; i < len; ++i) {
+		unsigned int chan = CR_CHAN(cmd->chanlist[i]);
+		unsigned int range = CR_RANGE(cmd->chanlist[i]);
+
 		if (i >= NUMCHANNELS)
 			break;
-		this_usbduxsub->dux_commands[i + 2] =
-		    create_adc_command(chan, range);
-	}
 
-	result = send_dux_commands(dev, SENDADCOMMANDS);
-	if (result < 0) {
-		up(&this_usbduxsub->sem);
-		return result;
+		devpriv->dux_commands[i + 2] = create_adc_command(chan, range);
 	}
 
-	if (this_usbduxsub->high_speed) {
+	ret = send_dux_commands(dev, SENDADCOMMANDS);
+	if (ret < 0)
+		goto ai_cmd_exit;
+
+	if (devpriv->high_speed) {
 		/*
 		 * every channel gets a time window of 125us. Thus, if we
 		 * sample all 8 channels we need 1ms. If we sample only one
 		 * channel we need only 125us
 		 */
-		this_usbduxsub->ai_interval = 1;
+		devpriv->ai_interval = 1;
 		/* find a power of 2 for the interval */
-		while ((this_usbduxsub->ai_interval) < (cmd->chanlist_len)) {
-			this_usbduxsub->ai_interval =
-			    (this_usbduxsub->ai_interval) * 2;
-		}
-		this_usbduxsub->ai_timer = cmd->scan_begin_arg / (125000 *
-							  (this_usbduxsub->
-							   ai_interval));
+		while (devpriv->ai_interval < len)
+			devpriv->ai_interval *= 2;
+
+		devpriv->ai_timer = cmd->scan_begin_arg /
+				    (125000 * devpriv->ai_interval);
 	} else {
 		/* interval always 1ms */
-		this_usbduxsub->ai_interval = 1;
-		this_usbduxsub->ai_timer = cmd->scan_begin_arg / 1000000;
+		devpriv->ai_interval = 1;
+		devpriv->ai_timer = cmd->scan_begin_arg / 1000000;
 	}
-	if (this_usbduxsub->ai_timer < 1) {
-		up(&this_usbduxsub->sem);
-		return -EINVAL;
+	if (devpriv->ai_timer < 1) {
+		ret = -EINVAL;
+		goto ai_cmd_exit;
 	}
-	this_usbduxsub->ai_counter = this_usbduxsub->ai_timer;
+
+	devpriv->ai_counter = devpriv->ai_timer;
 
 	if (cmd->stop_src == TRIG_COUNT) {
 		/* data arrives as one packet */
-		this_usbduxsub->ai_sample_count = cmd->stop_arg;
-		this_usbduxsub->ai_continous = 0;
+		devpriv->ai_sample_count = cmd->stop_arg;
+		devpriv->ai_continous = 0;
 	} else {
 		/* continous acquisition */
-		this_usbduxsub->ai_continous = 1;
-		this_usbduxsub->ai_sample_count = 0;
+		devpriv->ai_continous = 1;
+		devpriv->ai_sample_count = 0;
 	}
 
 	if (cmd->start_src == TRIG_NOW) {
 		/* enable this acquisition operation */
-		this_usbduxsub->ai_cmd_running = 1;
+		devpriv->ai_cmd_running = 1;
 		ret = usbduxsub_submit_inurbs(dev);
 		if (ret < 0) {
-			this_usbduxsub->ai_cmd_running = 0;
+			devpriv->ai_cmd_running = 0;
 			/* fixme: unlink here?? */
-			up(&this_usbduxsub->sem);
-			return ret;
+			goto ai_cmd_exit;
 		}
 		s->async->inttrig = NULL;
 	} else {
@@ -969,8 +963,11 @@ static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		/* wait for an internal signal */
 		s->async->inttrig = usbdux_ai_inttrig;
 	}
-	up(&this_usbduxsub->sem);
-	return 0;
+
+ai_cmd_exit:
+	up(&devpriv->sem);
+
+	return ret;
 }
 
 /* Mode 0 is used to get a single conversion on demand */