patch "staging: comedi: usbduxsigma: don't clobber ai_timer in command test" added to staging-testing

patch "staging: comedi: usbduxsigma: don't clobber ai_timer in command test" added to staging-testing

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: comedi: usbduxsigma: don't clobber ai_timer in command test

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the staging-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


>From 423b24c37dd5794a674c74b0ed56392003a69891 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 23 Jul 2015 16:46:57 +0100
Subject: staging: comedi: usbduxsigma: don't clobber ai_timer in command test

`devpriv->ai_timer` is used while an asynchronous command is running on
the AI subdevice.  It also gets modified by the subdevice's `cmdtest`
handler for checking new asynchronous commands
(`usbduxsigma_ai_cmdtest()`), which is not correct as it's allowed to
check new commands while an old command is still running.  Fix it by
moving the code which sets up `devpriv->ai_timer` and
`devpriv->ai_interval` into the subdevice's `cmd` handler,
`usbduxsigma_ai_cmd()`.

Note that the removed code in `usbduxsigma_ai_cmdtest()` checked that
`devpriv->ai_timer` did not end up less than than 1, but that could not
happen because `cmd->scan_begin_arg` had already been checked to be at
least the minimum required value (at least when `cmd->scan_begin_src ==
TRIG_TIMER`, which had also been checked to be the case).

Fixes: b986be8527c7 ("staging: comedi: usbduxsigma: tidy up analog input command support)
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: Bernd Porr <mail@berndporr.me.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: <stable@vger.kernel.org> # 3.19 onwards
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/comedi/drivers/usbduxsigma.c | 37 ++++++++++++----------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index 51846adf8340..2d684747a639 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -551,27 +551,6 @@ static int usbduxsigma_ai_cmdtest(struct comedi_device *dev,
 	if (err)
 		return 3;
 
-	/* Step 4: fix up any arguments */
-
-	if (high_speed) {
-		/*
-		 * every 2 channels get a time window of 125us. Thus, if we
-		 * sample all 16 channels we need 1ms. If we sample only one
-		 * channel we need only 125us
-		 */
-		devpriv->ai_interval = interval;
-		devpriv->ai_timer = cmd->scan_begin_arg / (125000 * interval);
-	} else {
-		/* interval always 1ms */
-		devpriv->ai_interval = 1;
-		devpriv->ai_timer = cmd->scan_begin_arg / 1000000;
-	}
-	if (devpriv->ai_timer < 1)
-		err |= -EINVAL;
-
-	if (err)
-		return 4;
-
 	return 0;
 }
 
@@ -669,6 +648,22 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
 
 	down(&devpriv->sem);
 
+	if (devpriv->high_speed) {
+		/*
+		 * every 2 channels get a time window of 125us. Thus, if we
+		 * sample all 16 channels we need 1ms. If we sample only one
+		 * channel we need only 125us
+		 */
+		unsigned int interval = usbduxsigma_chans_to_interval(len);
+
+		devpriv->ai_interval = interval;
+		devpriv->ai_timer = cmd->scan_begin_arg / (125000 * interval);
+	} else {
+		/* interval always 1ms */
+		devpriv->ai_interval = 1;
+		devpriv->ai_timer = cmd->scan_begin_arg / 1000000;
+	}
+
 	for (i = 0; i < len; i++) {
 		unsigned int chan  = CR_CHAN(cmd->chanlist[i]);
 
-- 
2.4.6