From: Ian Abbott Date: Wed, 29 Oct 2014 17:35:12 +0000 (+0000) Subject: staging: comedi: das16: use spin-lock when setting timer X-Git-Tag: firefly_0821_release~176^2~2665^2~553 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0a43f75ef57fcf20b9637fa49889e6721ceb5ea7;p=firefly-linux-kernel-4.4.55.git staging: comedi: das16: use spin-lock when setting timer "das16" sets a timer running in `das16_cmd_exec()` and sets `devpriv->timer_running` to indicate that it is running. The timer expiration routine `das16_timer_interrupt()` checks `devpriv->timer_running` to check whether it needs to reschedule the timer, but this is not synchronized with `das16_cmd_exec()`. Since `das16_cancel()` acquires the `dev->spinlock` spin-lock when clearing `devpriv->timer_running` and removing the timer from the queue, use the same spin-lock in `das16_cmd_exec()` and `das16_timer_interrupt()` around the setting and checking of `devpriv->timer_running`. Since `das16_interrupt()` (called from `das16_timer_interrupt()`) checks whether DMA is enabled in the device while holding `dev->spinlock`, and DMA is enabled by `das16_cmd_exec()` around the time it schedules the timer, enable the DMA in the device while holding the spin-lock. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c index 4556af109eae..8e512b241653 100644 --- a/drivers/staging/comedi/drivers/das16.c +++ b/drivers/staging/comedi/drivers/das16.c @@ -595,11 +595,14 @@ static void das16_timer_interrupt(unsigned long arg) { struct comedi_device *dev = (struct comedi_device *)arg; struct das16_private_struct *devpriv = dev->private; + unsigned long flags; das16_interrupt(dev); + spin_lock_irqsave(&dev->spinlock, flags); if (devpriv->timer_running) mod_timer(&devpriv->timer, jiffies + timer_period()); + spin_unlock_irqrestore(&dev->spinlock, flags); } static int das16_ai_check_chanlist(struct comedi_device *dev, @@ -816,7 +819,8 @@ static int das16_cmd_exec(struct comedi_device *dev, struct comedi_subdevice *s) enable_dma(devpriv->dma_chan); release_dma_lock(flags); - /* set up interrupt */ + /* set up timer */ + spin_lock_irqsave(&dev->spinlock, flags); devpriv->timer_running = 1; devpriv->timer.expires = jiffies + timer_period(); add_timer(&devpriv->timer); @@ -825,6 +829,7 @@ static int das16_cmd_exec(struct comedi_device *dev, struct comedi_subdevice *s) if (devpriv->can_burst) outb(0, dev->iobase + DAS1600_CONV_REG); + spin_unlock_irqrestore(&dev->spinlock, flags); return 0; }