linux-kernel - Re: [PATCH] staging: comedi: usbduxfast: Improve unlocking of a mutex in usbduxfast_ai_insn

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Message-ID: <20171103141412.GA5094@kroah.com>
Date:   Fri, 3 Nov 2017 15:14:12 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Ian Abbott <abbotti@....co.uk>
Cc:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        devel@...verdev.osuosl.org,
        H Hartley Sweeten <hsweeten@...ionengravers.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] staging: comedi: usbduxfast: Improve unlocking of a
 mutex in usbduxfast_ai_insn_read()

On Fri, Nov 03, 2017 at 02:00:18PM +0000, Ian Abbott wrote:
> On 02/11/17 19:40, SF Markus Elfring wrote:
> > From: Markus Elfring <elfring@...rs.sourceforge.net>
> > Date: Thu, 2 Nov 2017 20:30:31 +0100
> > 
> > * Add a jump target so that a call of the function "mutex_unlock" is stored
> >    only twice in this function implementation.
> > 
> > * Replace five calls by goto statements.
> > 
> > This issue was detected by using the Coccinelle software.
> > 
> > Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> > ---
> >   drivers/staging/comedi/drivers/usbduxfast.c | 24 ++++++++++++------------
> >   1 file changed, 12 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/staging/comedi/drivers/usbduxfast.c b/drivers/staging/comedi/drivers/usbduxfast.c
> > index 608403c7586b..e5884faf7275 100644
> > --- a/drivers/staging/comedi/drivers/usbduxfast.c
> > +++ b/drivers/staging/comedi/drivers/usbduxfast.c
> > @@ -777,8 +777,8 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
> >   	if (devpriv->ai_cmd_running) {
> >   		dev_err(dev->class_dev,
> >   			"ai_insn_read not possible, async cmd is running\n");
> > -		mutex_unlock(&devpriv->mut);
> > -		return -EBUSY;
> > +		ret = -EBUSY;
> > +		goto unlock;
> >   	}
> >   	/* set command for the first channel */
> > @@ -798,10 +798,8 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
> >   	usbduxfast_cmd_data(dev, 6, 0x01, 0x00, rngmask, 0x00);
> >   	ret = usbduxfast_send_cmd(dev, SENDADCOMMANDS);
> > -	if (ret < 0) {
> > -		mutex_unlock(&devpriv->mut);
> > -		return ret;
> > -	}
> > +	if (ret < 0)
> > +		goto unlock;
> >   	for (i = 0; i < PACKETS_TO_IGNORE; i++) {
> >   		ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, BULKINEP),
> > @@ -809,8 +807,7 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
> >   				   &actual_length, 10000);
> >   		if (ret < 0) {
> >   			dev_err(dev->class_dev, "insn timeout, no data\n");
> > -			mutex_unlock(&devpriv->mut);
> > -			return ret;
> > +			goto unlock;
> >   		}
> >   	}
> > @@ -820,14 +817,13 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
> >   				   &actual_length, 10000);
> >   		if (ret < 0) {
> >   			dev_err(dev->class_dev, "insn data error: %d\n", ret);
> > -			mutex_unlock(&devpriv->mut);
> > -			return ret;
> > +			goto unlock;
> >   		}
> >   		n = actual_length / sizeof(u16);
> >   		if ((n % 16) != 0) {
> >   			dev_err(dev->class_dev, "insn data packet corrupted\n");
> > -			mutex_unlock(&devpriv->mut);
> > -			return -EINVAL;
> > +			ret = -EINVAL;
> > +			goto unlock;
> >   		}
> >   		for (j = chan; (j < n) && (i < insn->n); j = j + 16) {
> >   			data[i] = ((u16 *)(devpriv->inbuf))[j];
> > @@ -838,6 +834,10 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
> >   	mutex_unlock(&devpriv->mut);
> >   	return insn->n;
> 
> Minor niggle: You could also remove that call to mutex_unlock() by replacing
> the above three lines with:
> 
> 	ret = insn->n;
> 
> which will fall through to the 'unlock:' label below.

FYI, you are responding to someone who is on my blacklist and I never
accept patches from.  I wouldn't waste my time reviewing any patches
from them, sorry.

greg k-h