Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752263AbaBNLyj (ORCPT ); Fri, 14 Feb 2014 06:54:39 -0500 Received: from mail.mev.co.uk ([62.49.15.74]:32914 "EHLO mail.mev.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751065AbaBNLyh (ORCPT ); Fri, 14 Feb 2014 06:54:37 -0500 Message-ID: <52FE03F4.70908@mev.co.uk> Date: Fri, 14 Feb 2014 11:54:28 +0000 From: Ian Abbott User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Chase Southwood , gregkh@linuxfoundation.org CC: hsweeten@visionengravers.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] Staging: comedi: clean up conditional statement in addi_apci_3xxx.c References: <1392262167-4073-1-git-send-email-chase.southwood@yahoo.com> <1392339746-3901-1-git-send-email-chase.southwood@yahoo.com> In-Reply-To: <1392339746-3901-1-git-send-email-chase.southwood@yahoo.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-02-14 01:02, Chase Southwood wrote: > 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 > --- > > 2: Addressed all of the comments provided by Hartley regarding correct > structure of this patch. > > Hopefully everything looks better! > > drivers/staging/comedi/drivers/addi_apci_3xxx.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/drivers/staging/comedi/drivers/addi_apci_3xxx.c b/drivers/staging/comedi/drivers/addi_apci_3xxx.c > index ceadf8e..1f3b668 100644 > --- a/drivers/staging/comedi/drivers/addi_apci_3xxx.c > +++ b/drivers/staging/comedi/drivers/addi_apci_3xxx.c > @@ -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; > > /* > @@ -688,12 +688,13 @@ 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 { > - /* changing any channel in port 2 changes the entire port */ > - mask = 0xff0000; > + else > + /* changing any channel in port 2 changes the entire port */ > + mask = 0xff0000; > } > > ret = comedi_dio_insn_config(dev, s, insn, data, mask); > Looks okay this time. :) Reviewed-by: Ian Abbott -- -=( Ian Abbott @ MEV Ltd. E-mail: )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/