Commit b0377d4b authored Feb 13, 2014 by Chase Southwood Committed by Greg Kroah-Hartman Feb 14, 2014

Staging: comedi: clean up conditional statement in addi_apci_3xxx.c

In this conditional statement, if (chan < 16), but the instruction passed
in data[0] is INSN_CONFIG_DIO_QUERY, the function does not return early,
but the else-branch does not get executed either. As a result, mask
would be used uninitialized in the next line. We want
comedi_dio_insn_config() to use a chan_mask based on the chanspec for the
INSN_CONFIG_DIO_QUERY instruction, so mask should be initialized to 0.
Then, if instead the instruction is INSN_CONFIG_DIO_{INPUT,OUTPUT}, we
return an error if (chan < 16) as these are invalid instructions for
ports 0 and 1, or update the mask otherwise, so all the io_bits are
modified for port 2. This ensures that mask is always initialized by the
time it is used.

Signed-off-by: Chase Southwood <chase.southwood@yahoo.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6bc2b856

drivers/staging/comedi/drivers/addi_apci_3xxx.c

+7 −6

Original line number	Diff line number	Diff line
		@@ -680,7 +680,7 @@ static int apci3xxx_dio_insn_config(struct comedi_device *dev,
		unsigned int *data)
		{
		unsigned int chan = CR_CHAN(insn->chanspec);
		unsigned int mask;
		unsigned int mask = 0;
		int ret;

		/*
		@@ -688,10 +688,11 @@ static int apci3xxx_dio_insn_config(struct comedi_device *dev,
		* Port 1 (channels 8-15) are always outputs
		* Port 2 (channels 16-23) are programmable i/o
		*/
		if (chan < 16) {
		if (data[0] != INSN_CONFIG_DIO_QUERY)
		if (data[0] != INSN_CONFIG_DIO_QUERY) {
		/* ignore all other instructions for ports 0 and 1 */
		if (chan < 16)
		return -EINVAL;
		} else {
		else
		/* changing any channel in port 2 changes the entire port */
		mask = 0xff0000;
		}