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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: b986be8527 ("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>
This commit is contained in:
Ian Abbott 2015-07-23 16:46:57 +01:00 committed by Greg Kroah-Hartman
parent ab74359822
commit 423b24c37d
1 changed files with 16 additions and 21 deletions
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37
drivers/staging/comedi/drivers/usbduxsigma.c
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@ -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]);