[PATCH 14/49] staging: comedi: dmm32at: factor out step 5 of (*do_cmdtest)
Ian Abbott
abbotti at mev.co.uk
Wed Apr 16 16:46:13 UTC 2014
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 <hsweeten at visionengravers.com>
> Cc: Ian Abbott <abbotti at mev.co.uk>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> ---
> drivers/staging/comedi/drivers/dmm32at.c | 51 +++++++++++++++++++-------------
> 1 file changed, 30 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/dmm32at.c b/drivers/staging/comedi/drivers/dmm32at.c
> index c8a36eb..c6a6930 100644
> --- a/drivers/staging/comedi/drivers/dmm32at.c
> +++ b/drivers/staging/comedi/drivers/dmm32at.c
> @@ -243,13 +243,39 @@ static int dmm32at_ns_to_timer(unsigned int *ns, int round)
> return *ns;
> }
>
> +static int dmm32at_ai_check_chanlist(struct comedi_device *dev,
> + struct comedi_subdevice *s,
> + struct comedi_cmd *cmd)
> +{
> + unsigned int chan0 = CR_CHAN(cmd->chanlist[0]);
> + unsigned int range0 = CR_RANGE(cmd->chanlist[0]);
> + int i;
> +
> + for (i = 1; i < cmd->chanlist_len; i++) {
> + unsigned int chan = CR_CHAN(cmd->chanlist[i]);
> + unsigned int range = CR_RANGE(cmd->chanlist[i]);
> +
> + if (chan != (chan0 + i) % s->n_chan) {
> + dev_err(dev->class_dev,
> + "chanlist must be consecutive channels, counting upwards\n");
> + return -EINVAL;
> + }
> +
> + if (range != range0) {
> + dev_err(dev->class_dev,
> + "chanlist must all have the same range\n");
> + return -EINVAL;
> + }
> + }
> + return 0;
> +}
> +
> static int dmm32at_ai_cmdtest(struct comedi_device *dev,
> struct comedi_subdevice *s,
> struct comedi_cmd *cmd)
> {
> int err = 0;
> int tmp;
> - int start_chan, gain, i;
>
> /* Step 1 : check if triggers are trivially valid */
>
> @@ -349,26 +375,9 @@ static int dmm32at_ai_cmdtest(struct comedi_device *dev,
> if (err)
> return 4;
>
> - /* step 5 check the channel list, the channel list for this
> - board must be consecutive and gains must be the same */
> -
> - if (cmd->chanlist) {
> - gain = CR_RANGE(cmd->chanlist[0]);
> - start_chan = CR_CHAN(cmd->chanlist[0]);
> - for (i = 1; i < cmd->chanlist_len; i++) {
> - if (CR_CHAN(cmd->chanlist[i]) !=
> - (start_chan + i) % s->n_chan) {
> - comedi_error(dev,
> - "entries in chanlist must be consecutive channels, counting upwards\n");
> - err++;
> - }
> - if (CR_RANGE(cmd->chanlist[i]) != gain) {
> - comedi_error(dev,
> - "entries in chanlist must all have the same gain\n");
> - err++;
> - }
> - }
> - }
> + /* Step 5: check channel list */
> +
> + err |= dmm32at_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 dmm32at_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 dmm32at_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: <abbotti at mev.co.uk> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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