[PATCH] staging: comedi: usbduxfast: Improve unlocking of a mutex in usbduxfast_ai_insn_read()

[SF Markus Elfring]

From: Markus Elfring <elfr...@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 <elfr...@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;
+
+unlock:
+       mutex_unlock(&devpriv->mut);
+       return ret;
 }
 
 static int usbduxfast_upload_firmware(struct comedi_device *dev,
-- 
2.15.0