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/ni_at_a2150.c | 71 ++++++++++++++++------------
1 file changed, 42 insertions(+), 29 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_at_a2150.c b/drivers/staging/comedi/drivers/ni_at_a2150.c
index dc1c47c..eefdd01 100644
--- a/drivers/staging/comedi/drivers/ni_at_a2150.c
+++ b/drivers/staging/comedi/drivers/ni_at_a2150.c
@@ -287,14 +287,51 @@ static int a2150_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
return 0;
}
+static int a2150_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 aref0 = CR_AREF(cmd->chanlist[0]);
+ int i;
+
+ if (cmd->chanlist_len == 2 && (chan0 == 1 || chan0 == 3)) {
+ dev_err(dev->class_dev,
+ "length 2 chanlist must be channels 0,1 or channels 2,3\n");
+ return -EINVAL;
+ }
+ if (cmd->chanlist_len == 3) {
+ dev_err(dev->class_dev,
+ "chanlist must have 1,2 or 4 channels\n");
+ return -EINVAL;
+ }
+ for (i = 1; i < cmd->chanlist_len; i++) {
+ unsigned int chan = CR_CHAN(cmd->chanlist[i]);
+ unsigned int aref = CR_AREF(cmd->chanlist[i]);
+
+ if (chan != (chan0 + i)) {
+ dev_err(dev->class_dev,
+ "chanlist must be consecutive channels, counting upwards\n");
+ return -EINVAL;
+ }
+
+ if (chan == 0 || chan == 2)
+ aref0 = aref;
+ if (aref != aref0) {
+ dev_err(dev->class_dev,
+ "channels 0/1 and 2/3 must have the same analog reference\n");
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
static int a2150_ai_cmdtest(struct comedi_device *dev,
struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
const struct a2150_board *thisboard = comedi_board(dev);
int err = 0;
int tmp;
- int startChan;
- int i;
/* Step 1 : check if triggers are trivially valid */
@@ -347,33 +384,9 @@ static int a2150_ai_cmdtest(struct comedi_device *dev,
if (err)
return 4;
- /* check channel/gain list against card's limitations */
- if (cmd->chanlist) {
- startChan = CR_CHAN(cmd->chanlist[0]);
- for (i = 1; i < cmd->chanlist_len; i++) {
- if (CR_CHAN(cmd->chanlist[i]) != (startChan + i)) {
- comedi_error(dev,
- "entries in chanlist must be consecutive channels, counting upwards\n");
- err++;
- }
- }
- if (cmd->chanlist_len == 2 && CR_CHAN(cmd->chanlist[0]) == 1) {
- comedi_error(dev,
- "length 2 chanlist must be channels 0,1 or channels 2,3");
- err++;
- }
- if (cmd->chanlist_len == 3) {
- comedi_error(dev,
- "chanlist must have 1,2 or 4 channels");
- err++;
- }
- if (CR_AREF(cmd->chanlist[0]) != CR_AREF(cmd->chanlist[1]) ||
- CR_AREF(cmd->chanlist[2]) != CR_AREF(cmd->chanlist[3])) {
- comedi_error(dev,
- "channels 0/1 and 2/3 must have the same analog reference");
- err++;
- }
- }
+ /* Step 5: check channel list */
+
+ err |= a2150_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 a2150_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 a2150_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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