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Subject[PATCH] staging: comedi: usbduxsigma: Improve unlocking of a mutex in three functions
Date
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Thu, 2 Nov 2017 21:16:50 +0100

* Add a jump target so that a call of the function "mutex_unlock" is stored
only twice in these function implementations.

* Replace seven 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/usbduxsigma.c | 48 +++++++++++++++-------------
1 file changed, 26 insertions(+), 22 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index 456e9f13becb..7e8284ed265a 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -672,10 +672,8 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
devpriv->dux_commands[8] = sysred;

ret = usbbuxsigma_send_cmd(dev, USBBUXSIGMA_AD_CMD);
- if (ret < 0) {
- mutex_unlock(&devpriv->mut);
- return ret;
- }
+ if (ret < 0)
+ goto unlock;

devpriv->ai_counter = devpriv->ai_timer;

@@ -686,8 +684,7 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
devpriv->n_ai_urbs, 1);
if (ret < 0) {
devpriv->ai_cmd_running = 0;
- mutex_unlock(&devpriv->mut);
- return ret;
+ goto unlock;
}
s->async->inttrig = NULL;
} else { /* TRIG_INT */
@@ -697,6 +694,10 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
mutex_unlock(&devpriv->mut);

return 0;
+
+unlock:
+ mutex_unlock(&devpriv->mut);
+ return ret;
}

static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
@@ -714,8 +715,8 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,

mutex_lock(&devpriv->mut);
if (devpriv->ai_cmd_running) {
- mutex_unlock(&devpriv->mut);
- return -EBUSY;
+ ret = -EBUSY;
+ goto unlock;
}

create_adc_command(chan, &muxsg0, &muxsg1);
@@ -730,19 +731,15 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,

/* adc commands */
ret = usbbuxsigma_send_cmd(dev, USBDUXSIGMA_SINGLE_AD_CMD);
- if (ret < 0) {
- mutex_unlock(&devpriv->mut);
- return ret;
- }
+ if (ret < 0)
+ goto unlock;

for (i = 0; i < insn->n; i++) {
u32 val;

ret = usbduxsigma_receive_cmd(dev, USBDUXSIGMA_SINGLE_AD_CMD);
- if (ret < 0) {
- mutex_unlock(&devpriv->mut);
- return ret;
- }
+ if (ret < 0)
+ goto unlock;

/* 32 bits big endian from the A/D converter */
val = be32_to_cpu(get_unaligned((__be32
@@ -753,6 +750,10 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
mutex_unlock(&devpriv->mut);

return insn->n;
+
+unlock:
+ mutex_unlock(&devpriv->mut);
+ return ret;
}

static int usbduxsigma_ao_insn_read(struct comedi_device *dev,
@@ -782,8 +783,8 @@ static int usbduxsigma_ao_insn_write(struct comedi_device *dev,

mutex_lock(&devpriv->mut);
if (devpriv->ao_cmd_running) {
- mutex_unlock(&devpriv->mut);
- return -EBUSY;
+ ret = -EBUSY;
+ goto unlock;
}

for (i = 0; i < insn->n; i++) {
@@ -791,15 +792,18 @@ static int usbduxsigma_ao_insn_write(struct comedi_device *dev,
devpriv->dux_commands[2] = data[i]; /* value */
devpriv->dux_commands[3] = chan; /* channel number */
ret = usbbuxsigma_send_cmd(dev, USBDUXSIGMA_DA_CMD);
- if (ret < 0) {
- mutex_unlock(&devpriv->mut);
- return ret;
- }
+ if (ret < 0)
+ goto unlock;
+
s->readback[chan] = data[i];
}
mutex_unlock(&devpriv->mut);

return insn->n;
+
+unlock:
+ mutex_unlock(&devpriv->mut);
+ return ret;
}

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