From: H Hartley Sweeten <hsweeten@visionengravers.com>
Date: Tue, 9 Sep 2014 23:16:00 +0000 (-0700)
Subject: staging: comedi: rtd520: prevent "empty acquisition" async command
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8c602c498cd88faa78e17acc7efa29a36012e728;p=linux-beck.git

staging: comedi: rtd520: prevent "empty acquisition" async command

This driver currently allows a cmd->stop_src == TRIG_COUNT with a cmd->stop_arg
of 0. The (*do_cmd) then sets up and starts the command without handling the "empty
acquisition". This results in the interrupt function trying to transfer 0 data
samples.

Validate that the cmd->stop_arg is >= 1 in the (*do_cmdtest) to prevent the
"empty acquisition".

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>
---

diff --git a/drivers/staging/comedi/drivers/rtd520.c b/drivers/staging/comedi/drivers/rtd520.c
index f0bf3edf5a31..7d4cb140959c 100644
--- a/drivers/staging/comedi/drivers/rtd520.c
+++ b/drivers/staging/comedi/drivers/rtd520.c
@@ -874,12 +874,10 @@ static int rtd_ai_cmdtest(struct comedi_device *dev,
 
 	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);
 
-	if (cmd->stop_src == TRIG_COUNT) {
-		/* TODO check for rounding error due to counter wrap */
-	} else {
-		/* TRIG_NONE */
+	if (cmd->stop_src == TRIG_COUNT)
+		err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
+	else	/* TRIG_NONE */
 		err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
-	}
 
 	if (err)
 		return 3;