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Subject[PATCH] staging: comedi: usbduxfast: Improve unlocking of a mutex in usbduxfast_ai_insn_read()
Date
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;
+
+unlock:
+ mutex_unlock(&devpriv->mut);
+ return ret;
}

static int usbduxfast_upload_firmware(struct comedi_device *dev,
--
2.15.0
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