From 27a90695e02759ccab58ca610af4f8ed79d8a35c Mon Sep 17 00:00:00 2001 From: Ksenija Stanojevic Date: Fri, 2 Oct 2015 22:07:54 +0200 Subject: [PATCH] Staging: comedi: Use mutex instead of semaphore in usbduxfast.c Replace binary semaphore with mutex because mutex gives better performance. This change is safe because the thread that decrements the value of semaphore is also the one that increments it, and acts like a mutex where owner of the lock is the only one that can release the lock. Signed-off-by: Ksenija Stanojevic Reviewed-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- 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 c6b2a6582127..10f94ec34536 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 = { -- 2.30.2