On 2014-04-15 18:37, H Hartley Sweeten wrote:
Step 5 of the (*do_cmdtest) validates that the chanlist, chan/range/aref/etc, is compatible with the actual hardware. At this point in the (*do_cmdtest) the chanlist is valid, due to checks in the core, so the sanity check is not needed.For aesthetics, factor the step 5 code into a helper function. Tidy up the factored out code. Signed-off-by: H Hartley Sweeten <hswee...@visionengravers.com> Cc: Ian Abbott <abbo...@mev.co.uk> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/staging/comedi/drivers/das1800.c | 37 +++++++++++++++++++------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c index c67f67a..b675f4e 100644 --- a/drivers/staging/comedi/drivers/das1800.c +++ b/drivers/staging/comedi/drivers/das1800.c @@ -757,7 +757,25 @@ static unsigned int burst_convert_arg(unsigned int convert_arg, int round_mode) return micro_sec * 1000; } -/* test analog input cmd */ +static int das1800_ai_check_chanlist(struct comedi_device *dev, + struct comedi_subdevice *s, + struct comedi_cmd *cmd) +{ + unsigned int unipolar0 = CR_RANGE(cmd->chanlist[0]) & UNIPOLAR; + int i; + + for (i = 1; i < cmd->chanlist_len; i++) { + unsigned int unipolar = CR_RANGE(cmd->chanlist[i]) & UNIPOLAR; + + if (unipolar != unipolar0) { + dev_err(dev->class_dev, + "unipolar and bipolar ranges cannot be mixed in the chanlist\n"); + return -EINVAL; + } + } + return 0; +} + static int das1800_ai_do_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_cmd *cmd) @@ -766,8 +784,6 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev, struct das1800_private *devpriv = dev->private; int err = 0; unsigned int tmp_arg; - int i; - int unipolar; /* Step 1 : check if triggers are trivially valid */ @@ -872,18 +888,9 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev, if (err) return 4; - /* make sure user is not trying to mix unipolar and bipolar ranges */ - if (cmd->chanlist) { - unipolar = CR_RANGE(cmd->chanlist[0]) & UNIPOLAR; - for (i = 1; i < cmd->chanlist_len; i++) { - if (unipolar != (CR_RANGE(cmd->chanlist[i]) & UNIPOLAR)) { - comedi_error(dev, - "unipolar and bipolar ranges cannot be mixed in the chanlist"); - err++; - break; - } - } - } + /* Step 5: check channel list */ + + err |= das1800_ai_check_chanlist(dev, s, cmd); if (err) return 5;
As for the remarks in patch 02, it's possible for chanlist to be NULL or for chanlist_len to be 0, so das1800_ai_check_chanlist() should only be called if chanlist is non-NULL and chanlist_len is non-0.
But if chanlist is forced to be NULL by __comedi_get_user_chanlist() when chanlist_len is 0, it would be sufficient to check that chanlist is non-NULL before calling das1800_ai_check_chanlist().
The original code is buggy as well because it accesses cmd->chanlist[0] without checking cmd->chanlist_len.
-- -=( Ian Abbott @ MEV Ltd. E-mail: <abbo...@mev.co.uk> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
