Patch "staging: comedi: usbduxsigma: don't clobber ai_timer in command test" has been added to the 4.2-stable tree

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 the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-comedi-usbduxsigma-don-t-clobber-ai_timer-in-command-test.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ian Abbott <[email protected]>
Date: Thu, 23 Jul 2015 16:46:57 +0100
Subject: staging: comedi: usbduxsigma: don't clobber ai_timer in command test

From: Ian Abbott <[email protected]>

commit 423b24c37dd5794a674c74b0ed56392003a69891 upstream.

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).

---
 drivers/staging/comedi/drivers/usbduxsigma.c |   37 +++++++++++----------------
 1 file changed, 16 insertions(+), 21 deletions(-)

@@ -550,27 +550,6 @@ static int usbduxsigma_ai_cmdtest(struct
 	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;
 }
 

@@ -668,6 +647,22 @@ static int usbduxsigma_ai_cmd(struct com
 
 	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]);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.2/staging-comedi-usbduxsigma-don-t-clobber-ao_timer-in-command-test.patch queue-4.2/staging-comedi-adl_pci7x3x-fix-digital-output-on-pci-7230.patch queue-4.2/staging-comedi-usbduxsigma-don-t-clobber-ai_timer-in-command-test.patch