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/das800.c | 51 +++++++++++++++++++-------------- 1 file changed, 30 insertions(+), 21 deletions(-) diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c index ef5f65f..14420e0 100644 --- a/drivers/staging/comedi/drivers/das800.c +++ b/drivers/staging/comedi/drivers/das800.c @@ -300,6 +300,33 @@ static int das800_cancel(struct comedi_device *dev, struct comedi_subdevice *s) return 0; } +static int das800_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, 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 das800_ai_do_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_cmd *cmd) @@ -365,27 +392,9 @@ static int das800_ai_do_cmdtest(struct comedi_device *dev, if (err) return 4; - /* check channel/gain list against card's limitations */ - if (cmd->chanlist) { - unsigned int chan = CR_CHAN(cmd->chanlist[0]); - unsigned int range = CR_RANGE(cmd->chanlist[0]); - unsigned int next; - int i; - - for (i = 1; i < cmd->chanlist_len; i++) { - next = cmd->chanlist[i]; - if (CR_CHAN(next) != (chan + i) % N_CHAN_AI) { - dev_err(dev->class_dev, - "chanlist must be consecutive, counting upwards\n"); - err++; - } - if (CR_RANGE(next) != range) { - dev_err(dev->class_dev, - "chanlist must all have the same gain\n"); - err++; - } - } - } + /* Step 5: check channel list */ + + err |= das800_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 das800_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 das800_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
