staging: comedi: drivers: core validates chanlist_len max

The comedi core checks if the (cmd->chanlist_len > s->len_chanlist) when the
comedi_cmd is copied from user to kernel space by __comedi_get_user_cmd().
If so, the core returns -EINVAL and will not call the subdevice (*do_cmdtest)
and (*do_cmd).

Remove the unnecessary "max" checks in the comedi driver (*do_cmdtest) and
helper functions.
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/addi-data/hwdrv_apci3120.c

@@ -734,7 +734,6 @@ static int apci3120_ai_cmdtest(struct comedi_device *dev,
 			       struct comedi_subdevice *s,
 			       struct comedi_cmd *cmd)
 {
-	const struct addi_board *this_board = comedi_board(dev);
 	int err = 0;
 
 	/* Step 1 : check if triggers are trivially valid */
@@ -779,8 +778,6 @@ static int apci3120_ai_cmdtest(struct comedi_device *dev,
 	}
 
 	err |= cfc_check_trigger_arg_min(&cmd->chanlist_len, 1);
-	err |= cfc_check_trigger_arg_max(&cmd->chanlist_len,
-					 this_board->i_AiChannelList);
 
 	if (cmd->stop_src == TRIG_COUNT)
 		err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);

drivers/staging/comedi/drivers/adl_pci9118.c

@@ -1259,8 +1259,6 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 		err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
 
 	err |= cfc_check_trigger_arg_min(&cmd->chanlist_len, 1);
-	err |= cfc_check_trigger_arg_max(&cmd->chanlist_len,
-					 this_board->n_aichanlist);
 
 	err |= cfc_check_trigger_arg_min(&cmd->scan_end_arg,
 					 cmd->chanlist_len);

drivers/staging/comedi/drivers/pcl812.c

@@ -761,7 +761,6 @@ static int pcl812_ai_cmdtest(struct comedi_device *dev,
 		err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
 
 	err |= cfc_check_trigger_arg_min(&cmd->chanlist_len, 1);
-	err |= cfc_check_trigger_arg_max(&cmd->chanlist_len, MAX_CHANLIST_LEN);
 	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);
 
 	if (cmd->stop_src == TRIG_COUNT)

drivers/staging/comedi/drivers/rtd520.c

@@ -891,10 +891,6 @@ static int rtd_ai_cmdtest(struct comedi_device *dev,
 
 	/* step 4: fix up any arguments */
 
-	if (cmd->chanlist_len > RTD_MAX_CHANLIST) {
-		cmd->chanlist_len = RTD_MAX_CHANLIST;
-		err++;
-	}
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		tmp = cmd->scan_begin_arg;
 		rtd_ns_to_timer(&cmd->scan_begin_arg,