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@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxx> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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