[PATCH 0/4] Use mutex instead of semaphore

[PATCH 0/4] Use mutex instead of semaphore

[Ksenija Stanojevic]

This patchset replaces binary semaphore with mutex in comedi drivers.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>

Ksenija Stanojevic (4):
  Staging: comedi: Use mutex instead of semaphore
  Staging: comedi: Use mutex instead of semaphore
  Staging: comedi: Use mutex instead of semaphore
  Staging: comedi: Use mutex instead of semaphore

 drivers/staging/comedi/drivers/ni_usb6501.c  | 16 +++----
 drivers/staging/comedi/drivers/usbdux.c      | 64 ++++++++++++-------------
 drivers/staging/comedi/drivers/usbduxfast.c  | 36 +++++++-------
 drivers/staging/comedi/drivers/usbduxsigma.c | 70 ++++++++++++++--------------
 4 files changed, 93 insertions(+), 93 deletions(-)

-- 
1.9.1

[PATCH 1/4] Staging: comedi: Use mutex instead of semaphore

[Ksenija Stanojevic]

Replace binary semaphore with mutex because mutex gives better
performance.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
---
 drivers/staging/comedi/drivers/usbduxsigma.c | 70 ++++++++++++++--------------
 1 file changed, 35 insertions(+), 35 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c
index d49147b..456e9f1 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -173,7 +173,7 @@ struct usbduxsigma_private {
 	unsigned int ai_interval;
 	/* commands */
 	u8 *dux_commands;
-	struct semaphore sem;
+	struct mutex mut;
 };
 
 static void usbduxsigma_unlink_urbs(struct urb **urbs, int num_urbs)
@@ -199,10 +199,10 @@ static int usbduxsigma_ai_cancel(struct comedi_device *dev,
 {
 	struct usbduxsigma_private *devpriv = dev->private;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	/* unlink only if it is really running */
 	usbduxsigma_ai_stop(dev, devpriv->ai_cmd_running);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -325,10 +325,10 @@ static int usbduxsigma_ao_cancel(struct comedi_device *dev,
 {
 	struct usbduxsigma_private *devpriv = dev->private;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	/* unlink only if it is really running */
 	usbduxsigma_ao_stop(dev, devpriv->ao_cmd_running);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -609,19 +609,19 @@ static int usbduxsigma_ai_inttrig(struct comedi_device *dev,
 	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	if (!devpriv->ai_cmd_running) {
 		devpriv->ai_cmd_running = 1;
 		ret = usbduxsigma_submit_urbs(dev, devpriv->ai_urbs,
 					      devpriv->n_ai_urbs, 1);
 		if (ret < 0) {
 			devpriv->ai_cmd_running = 0;
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->async->inttrig = NULL;
 	}
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 1;
 }
@@ -638,7 +638,7 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
 	int ret;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->high_speed) {
 		/*
@@ -673,7 +673,7 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
 
 	ret = usbbuxsigma_send_cmd(dev, USBBUXSIGMA_AD_CMD);
 	if (ret < 0) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return ret;
 	}
 
@@ -686,7 +686,7 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
 					      devpriv->n_ai_urbs, 1);
 		if (ret < 0) {
 			devpriv->ai_cmd_running = 0;
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->async->inttrig = NULL;
@@ -694,7 +694,7 @@ static int usbduxsigma_ai_cmd(struct comedi_device *dev,
 		s->async->inttrig = usbduxsigma_ai_inttrig;
 	}
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -712,9 +712,9 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
 	int ret;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	if (devpriv->ai_cmd_running) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return -EBUSY;
 	}
 
@@ -731,7 +731,7 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
 	/* adc commands */
 	ret = usbbuxsigma_send_cmd(dev, USBDUXSIGMA_SINGLE_AD_CMD);
 	if (ret < 0) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return ret;
 	}
 
@@ -740,7 +740,7 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
 
 		ret = usbduxsigma_receive_cmd(dev, USBDUXSIGMA_SINGLE_AD_CMD);
 		if (ret < 0) {
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 
@@ -750,7 +750,7 @@ static int usbduxsigma_ai_insn_read(struct comedi_device *dev,
 		val &= 0x00ffffff;	/* strip status byte */
 		data[i] = comedi_offset_munge(s, val);
 	}
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return insn->n;
 }
@@ -763,9 +763,9 @@ static int usbduxsigma_ao_insn_read(struct comedi_device *dev,
 	struct usbduxsigma_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	ret = comedi_readback_insn_read(dev, s, insn, data);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -780,9 +780,9 @@ static int usbduxsigma_ao_insn_write(struct comedi_device *dev,
 	int ret;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	if (devpriv->ao_cmd_running) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return -EBUSY;
 	}
 
@@ -792,12 +792,12 @@ static int usbduxsigma_ao_insn_write(struct comedi_device *dev,
 		devpriv->dux_commands[3] = chan;	/* channel number */
 		ret = usbbuxsigma_send_cmd(dev, USBDUXSIGMA_DA_CMD);
 		if (ret < 0) {
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->readback[chan] = data[i];
 	}
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return insn->n;
 }
@@ -813,19 +813,19 @@ static int usbduxsigma_ao_inttrig(struct comedi_device *dev,
 	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	if (!devpriv->ao_cmd_running) {
 		devpriv->ao_cmd_running = 1;
 		ret = usbduxsigma_submit_urbs(dev, devpriv->ao_urbs,
 					      devpriv->n_ao_urbs, 0);
 		if (ret < 0) {
 			devpriv->ao_cmd_running = 0;
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->async->inttrig = NULL;
 	}
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 1;
 }
@@ -856,7 +856,7 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev,
 	err |= comedi_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);
 
 	if (err) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return 1;
 	}
 
@@ -905,7 +905,7 @@ static int usbduxsigma_ao_cmd(struct comedi_device *dev,
 	struct comedi_cmd *cmd = &s->async->cmd;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	/*
 	 * For now, only "scan" timing is supported.  A future version may
@@ -924,7 +924,7 @@ static int usbduxsigma_ao_cmd(struct comedi_device *dev,
 					      devpriv->n_ao_urbs, 0);
 		if (ret < 0) {
 			devpriv->ao_cmd_running = 0;
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->async->inttrig = NULL;
@@ -932,7 +932,7 @@ static int usbduxsigma_ao_cmd(struct comedi_device *dev,
 		s->async->inttrig = usbduxsigma_ao_inttrig;
 	}
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -963,7 +963,7 @@ static int usbduxsigma_dio_insn_bits(struct comedi_device *dev,
 	struct usbduxsigma_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	comedi_dio_update_state(s, data);
 
@@ -990,7 +990,7 @@ static int usbduxsigma_dio_insn_bits(struct comedi_device *dev,
 	ret = insn->n;
 
 done:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -1462,7 +1462,7 @@ static int usbduxsigma_auto_attach(struct comedi_device *dev,
 	if (!devpriv)
 		return -ENOMEM;
 
-	sema_init(&devpriv->sem, 1);
+	mutex_init(&devpriv->mut);
 
 	usb_set_intfdata(intf, devpriv);
 
@@ -1576,7 +1576,7 @@ static void usbduxsigma_detach(struct comedi_device *dev)
 	if (!devpriv)
 		return;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	/* force unlink all urbs */
 	usbduxsigma_ai_stop(dev, 1);
@@ -1585,7 +1585,7 @@ static void usbduxsigma_detach(struct comedi_device *dev)
 
 	usbduxsigma_free_usb_buffers(dev);
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 }
 
 static struct comedi_driver usbduxsigma_driver = {
-- 
1.9.1

[PATCH 2/4] Staging: comedi: Use mutex instead of semaphore

[Ksenija Stanojevic]

Replace binary semaphore with mutex because mutex gives better
performance.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
---
 drivers/staging/comedi/drivers/usbdux.c | 64 ++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 32 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbdux.c b/drivers/staging/comedi/drivers/usbdux.c
index 39710f2..f4f05d2 100644
--- a/drivers/staging/comedi/drivers/usbdux.c
+++ b/drivers/staging/comedi/drivers/usbdux.c
@@ -210,7 +210,7 @@ struct usbdux_private {
 	unsigned int ai_interval;
 	/* commands */
 	u8 *dux_commands;
-	struct semaphore sem;
+	struct mutex mut;
 };
 
 static void usbdux_unlink_urbs(struct urb **urbs, int num_urbs)
@@ -237,10 +237,10 @@ static int usbdux_ai_cancel(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 
 	/* prevent other CPUs from submitting new commands just now */
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	/* unlink only if the urb really has been submitted */
 	usbdux_ai_stop(dev, devpriv->ai_cmd_running);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -365,10 +365,10 @@ static int usbdux_ao_cancel(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 
 	/* prevent other CPUs from submitting a command just now */
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	/* unlink only if it is really running */
 	usbdux_ao_stop(dev, devpriv->ao_cmd_running);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return 0;
 }
@@ -646,7 +646,7 @@ static int usbdux_ai_inttrig(struct comedi_device *dev,
 	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (!devpriv->ai_cmd_running) {
 		devpriv->ai_cmd_running = 1;
@@ -662,7 +662,7 @@ static int usbdux_ai_inttrig(struct comedi_device *dev,
 	}
 
 ai_trig_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 	return ret;
 }
 
@@ -675,7 +675,7 @@ static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	int i;
 
 	/* block other CPUs from starting an ai_cmd */
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->ai_cmd_running)
 		goto ai_cmd_exit;
@@ -736,7 +736,7 @@ static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	}
 
 ai_cmd_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -754,7 +754,7 @@ static int usbdux_ai_insn_read(struct comedi_device *dev,
 	int ret = -EBUSY;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->ai_cmd_running)
 		goto ai_read_exit;
@@ -782,7 +782,7 @@ static int usbdux_ai_insn_read(struct comedi_device *dev,
 	}
 
 ai_read_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret ? ret : insn->n;
 }
@@ -795,9 +795,9 @@ static int usbdux_ao_insn_read(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	ret = comedi_readback_insn_read(dev, s, insn, data);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -814,7 +814,7 @@ static int usbdux_ao_insn_write(struct comedi_device *dev,
 	int ret = -EBUSY;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->ao_cmd_running)
 		goto ao_write_exit;
@@ -838,7 +838,7 @@ static int usbdux_ao_insn_write(struct comedi_device *dev,
 	}
 
 ao_write_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret ? ret : insn->n;
 }
@@ -854,7 +854,7 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (!devpriv->ao_cmd_running) {
 		devpriv->ao_cmd_running = 1;
@@ -870,7 +870,7 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 	}
 
 ao_trig_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 	return ret;
 }
 
@@ -960,7 +960,7 @@ static int usbdux_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	struct comedi_cmd *cmd = &s->async->cmd;
 	int ret = -EBUSY;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->ao_cmd_running)
 		goto ao_cmd_exit;
@@ -1002,7 +1002,7 @@ static int usbdux_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	}
 
 ao_cmd_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -1033,7 +1033,7 @@ static int usbdux_dio_insn_bits(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	comedi_dio_update_state(s, data);
 
@@ -1055,7 +1055,7 @@ static int usbdux_dio_insn_bits(struct comedi_device *dev,
 	data[1] = le16_to_cpu(devpriv->insn_buf[1]);
 
 dio_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret ? ret : insn->n;
 }
@@ -1070,7 +1070,7 @@ static int usbdux_counter_read(struct comedi_device *dev,
 	int ret = 0;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	for (i = 0; i < insn->n; i++) {
 		ret = send_dux_commands(dev, USBDUX_CMD_TIMER_RD);
@@ -1084,7 +1084,7 @@ static int usbdux_counter_read(struct comedi_device *dev,
 	}
 
 counter_read_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret ? ret : insn->n;
 }
@@ -1100,7 +1100,7 @@ static int usbdux_counter_write(struct comedi_device *dev,
 	int ret = 0;
 	int i;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	devpriv->dux_commands[1] = chan;
 
@@ -1112,7 +1112,7 @@ static int usbdux_counter_write(struct comedi_device *dev,
 			break;
 	}
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret ? ret : insn->n;
 }
@@ -1148,11 +1148,11 @@ static int usbdux_pwm_cancel(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	/* unlink only if it is really running */
 	usbdux_pwm_stop(dev, devpriv->pwm_cmd_running);
 	ret = send_dux_commands(dev, USBDUX_CMD_PWM_OFF);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -1257,7 +1257,7 @@ static int usbdux_pwm_start(struct comedi_device *dev,
 	struct usbdux_private *devpriv = dev->private;
 	int ret = 0;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->pwm_cmd_running)
 		goto pwm_start_exit;
@@ -1276,7 +1276,7 @@ static int usbdux_pwm_start(struct comedi_device *dev,
 		devpriv->pwm_cmd_running = 0;
 
 pwm_start_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -1576,7 +1576,7 @@ static int usbdux_auto_attach(struct comedi_device *dev,
 	if (!devpriv)
 		return -ENOMEM;
 
-	sema_init(&devpriv->sem, 1);
+	mutex_init(&devpriv->mut);
 
 	usb_set_intfdata(intf, devpriv);
 
@@ -1691,7 +1691,7 @@ static void usbdux_detach(struct comedi_device *dev)
 	if (!devpriv)
 		return;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	/* force unlink all urbs */
 	usbdux_pwm_stop(dev, 1);
@@ -1700,7 +1700,7 @@ static void usbdux_detach(struct comedi_device *dev)
 
 	usbdux_free_usb_buffers(dev);
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 }
 
 static struct comedi_driver usbdux_driver = {
-- 
1.9.1

[PATCH 3/4] Staging: comedi: Use mutex instead of semaphore

[Ksenija Stanojevic]

Replace binary semaphore with mutex because mutex gives better
performance.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
---
 drivers/staging/comedi/drivers/usbduxfast.c | 36 ++++++++++++++---------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbduxfast.c b/drivers/staging/comedi/drivers/usbduxfast.c
index c6b2a65..10f94ec 100644
--- a/drivers/staging/comedi/drivers/usbduxfast.c
+++ b/drivers/staging/comedi/drivers/usbduxfast.c
@@ -160,7 +160,7 @@ struct usbduxfast_private {
 	s8 *inbuf;
 	short int ai_cmd_running;	/* asynchronous command is running */
 	int ignore;		/* counter which ignores the first buffers */
-	struct semaphore sem;
+	struct mutex mut;
 };
 
 /*
@@ -221,9 +221,9 @@ static int usbduxfast_ai_cancel(struct comedi_device *dev,
 	struct usbduxfast_private *devpriv = dev->private;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	ret = usbduxfast_ai_stop(dev, 1);
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -444,7 +444,7 @@ static int usbduxfast_ai_inttrig(struct comedi_device *dev,
 	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (!devpriv->ai_cmd_running) {
 		devpriv->ai_cmd_running = 1;
@@ -452,14 +452,14 @@ static int usbduxfast_ai_inttrig(struct comedi_device *dev,
 		if (ret < 0) {
 			dev_err(dev->class_dev, "urbSubmit: err=%d\n", ret);
 			devpriv->ai_cmd_running = 0;
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		s->async->inttrig = NULL;
 	} else {
 		dev_err(dev->class_dev, "ai is already running\n");
 	}
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 	return 1;
 }
 
@@ -472,7 +472,7 @@ static int usbduxfast_ai_cmd(struct comedi_device *dev,
 	int j, ret;
 	long steps, steps_tmp;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 	if (devpriv->ai_cmd_running) {
 		ret = -EBUSY;
 		goto cmd_exit;
@@ -751,7 +751,7 @@ static int usbduxfast_ai_cmd(struct comedi_device *dev,
 	}
 
 cmd_exit:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -772,12 +772,12 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
 	int i, j, n, actual_length;
 	int ret;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	if (devpriv->ai_cmd_running) {
 		dev_err(dev->class_dev,
 			"ai_insn_read not possible, async cmd is running\n");
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return -EBUSY;
 	}
 
@@ -799,7 +799,7 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
 
 	ret = usbduxfast_send_cmd(dev, SENDADCOMMANDS);
 	if (ret < 0) {
-		up(&devpriv->sem);
+		mutex_unlock(&devpriv->mut);
 		return ret;
 	}
 
@@ -809,7 +809,7 @@ 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");
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 	}
@@ -820,13 +820,13 @@ 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);
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return ret;
 		}
 		n = actual_length / sizeof(u16);
 		if ((n % 16) != 0) {
 			dev_err(dev->class_dev, "insn data packet corrupted\n");
-			up(&devpriv->sem);
+			mutex_unlock(&devpriv->mut);
 			return -EINVAL;
 		}
 		for (j = chan; (j < n) && (i < insn->n); j = j + 16) {
@@ -835,7 +835,7 @@ static int usbduxfast_ai_insn_read(struct comedi_device *dev,
 		}
 	}
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return insn->n;
 }
@@ -930,7 +930,7 @@ static int usbduxfast_auto_attach(struct comedi_device *dev,
 	if (!devpriv)
 		return -ENOMEM;
 
-	sema_init(&devpriv->sem, 1);
+	mutex_init(&devpriv->mut);
 	usb_set_intfdata(intf, devpriv);
 
 	devpriv->duxbuf = kmalloc(SIZEOFDUXBUF, GFP_KERNEL);
@@ -989,7 +989,7 @@ static void usbduxfast_detach(struct comedi_device *dev)
 	if (!devpriv)
 		return;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	usb_set_intfdata(intf, NULL);
 
@@ -1003,7 +1003,7 @@ static void usbduxfast_detach(struct comedi_device *dev)
 
 	kfree(devpriv->duxbuf);
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 }
 
 static struct comedi_driver usbduxfast_driver = {
-- 
1.9.1

[PATCH 4/4] Staging: comedi: Use mutex instead of semaphore

[Ksenija Stanojevic]

Replace binary semaphore with mutex because mutex gives better
performance.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
---
 drivers/staging/comedi/drivers/ni_usb6501.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/comedi/drivers/ni_usb6501.c b/drivers/staging/comedi/drivers/ni_usb6501.c
index 88de8da..95b537a 100644
--- a/drivers/staging/comedi/drivers/ni_usb6501.c
+++ b/drivers/staging/comedi/drivers/ni_usb6501.c
@@ -166,7 +166,7 @@ enum commands {
 struct ni6501_private {
 	struct usb_endpoint_descriptor *ep_rx;
 	struct usb_endpoint_descriptor *ep_tx;
-	struct semaphore sem;
+	struct mutex mut;
 	u8 *usb_rx_buf;
 	u8 *usb_tx_buf;
 };
@@ -183,7 +183,7 @@ static int ni6501_port_command(struct comedi_device *dev, int command,
 	if (command != SET_PORT_DIR && !bitmap)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	switch (command) {
 	case READ_PORT:
@@ -248,7 +248,7 @@ static int ni6501_port_command(struct comedi_device *dev, int command,
 		ret = -EINVAL;
 	}
 end:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -265,7 +265,7 @@ static int ni6501_counter_command(struct comedi_device *dev, int command,
 	if ((command == READ_COUNTER || command ==  WRITE_COUNTER) && !val)
 		return -EINVAL;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	switch (command) {
 	case START_COUNTER:
@@ -338,7 +338,7 @@ static int ni6501_counter_command(struct comedi_device *dev, int command,
 		ret = -EINVAL;
 	}
 end:
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 
 	return ret;
 }
@@ -535,7 +535,7 @@ static int ni6501_auto_attach(struct comedi_device *dev,
 	if (ret)
 		return ret;
 
-	sema_init(&devpriv->sem, 1);
+	mutex_init(&devpriv->mut);
 	usb_set_intfdata(intf, devpriv);
 
 	ret = comedi_alloc_subdevices(dev, 2);
@@ -573,14 +573,14 @@ static void ni6501_detach(struct comedi_device *dev)
 	if (!devpriv)
 		return;
 
-	down(&devpriv->sem);
+	mutex_lock(&devpriv->mut);
 
 	usb_set_intfdata(intf, NULL);
 
 	kfree(devpriv->usb_rx_buf);
 	kfree(devpriv->usb_tx_buf);
 
-	up(&devpriv->sem);
+	mutex_unlock(&devpriv->mut);
 }
 
 static struct comedi_driver ni6501_driver = {
-- 
1.9.1

Re: [Outreachy kernel] [PATCH 0/4] Use mutex instead of semaphore

[Arnd Bergmann]

On Thursday 01 October 2015 18:05:57 Ksenija Stanojevic wrote:
> This patchset replaces binary semaphore with mutex in comedi drivers.
> 
> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
> 
> Ksenija Stanojevic (4):
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore

The changes all look good to me, but I think it would be nice to
expand the changelog a bit: in particular, how did you prove for
each file that it is safe to replace the semaphore with a mutex.

	Arnd

Re: [Outreachy kernel] [PATCH 0/4] Use mutex instead of semaphore

[Greg KH]

On Thu, Oct 01, 2015 at 06:05:57PM +0200, Ksenija Stanojevic wrote:
> This patchset replaces binary semaphore with mutex in comedi drivers.
> 
> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
> 
> Ksenija Stanojevic (4):
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore
>   Staging: comedi: Use mutex instead of semaphore

All 4 of these patches have the same subject, which is not good :(

Please use the driver name in the subject to make them unique, otherwise
it looks like something went wrong and you sent the same patch 4 times.

thanks,

greg k-h