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SubjectRe: [PATCH] staging: comedi: usbduxfast: Improve unlocking of a mutex in usbduxfast_ai_insn_read()
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On 02/11/17 19:40, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.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@users.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.

> +
> +unlock:
> + mutex_unlock(&devpriv->mut);
> + return ret;
> }
>
> static int usbduxfast_upload_firmware(struct comedi_device *dev,
>


--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@mev.co.uk> )=-
-=( Web: http://www.mev.co.uk/ )=-

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