From: Frank Mori Hess <fmhess@speakeasy.net>
Date: Sat, 5 May 2001 00:51:22 +0000 (+0000)
Subject: fixed null dereference that occured when interrupt was handled before driver was... 
X-Git-Tag: r0_7_59~73
X-Git-Url: http://git.tremily.us/gitweb.cgi?a=commitdiff_plain;h=52031fc71adca38f4ac49898fa8337b6371cfd34;p=comedi.git

fixed null dereference that occured when interrupt was handled before driver was fully attached
---

diff --git a/comedi/drivers/das800.c b/comedi/drivers/das800.c
index 5a10a526..9c26d7c6 100644
--- a/comedi/drivers/das800.c
+++ b/comedi/drivers/das800.c
@@ -319,16 +319,21 @@ static void das800_interrupt(int irq, void *d, struct pt_regs *regs)
 	sampl_t dataPoint;
 	comedi_device *dev = d;
 	comedi_subdevice *s = dev->read_subdev;	/* analog input subdevice */
-	comedi_async *async = s->async;
+	comedi_async *async;
 	int status;
 	unsigned long irq_flags;
 	static const int max_loops = 256;
 
 	status = inb(dev->iobase + DAS800_STATUS);
-	/* if interupt was not generated by board, quit */
+	/* if interupt was not generated by board or driver not attached, quit */
 	if(!(status & IRQ) || !(dev->attached))
 		return;
 
+	/* wait until here to initialize async, since we will get null dereference
+	 * if interrupt occurs before driver is fully attached!
+	 */
+	async = s->async;
+
 	// if hardware conversions are not enabled, then quit
 	comedi_spin_lock_irqsave(&dev->spinlock, irq_flags);
 	outb(CONTROL1, dev->iobase + DAS800_GAIN);	/* select base address + 7 to be STATUS2 register */
@@ -348,6 +353,7 @@ static void das800_interrupt(int irq, void *d, struct pt_regs *regs)
 	{
 		if( dataPoint & FIFO_OVF )
 		{
+			comedi_spin_unlock_irqrestore(&dev->spinlock, irq_flags);
 			comedi_error(dev, "DAS800 FIFO overflow");
 			das800_cancel(dev, dev->subdevices + 0);
 			comedi_error_done(dev, s);
@@ -423,6 +429,10 @@ static int das800_attach(comedi_device *dev, comedi_devconfig *it)
 	}
 	printk("\n");
 
+	/* allocate and initialize dev->private */
+	if(alloc_private(dev, sizeof(das800_private)) < 0)
+		return -ENOMEM;
+
 	if(iobase == 0)
 	{
 		printk("io base address required for das800\n");
@@ -464,10 +474,6 @@ static int das800_attach(comedi_device *dev, comedi_devconfig *it)
 
 	dev->board_name = thisboard->name;
 
-	/* allocate and initialize dev->private */
-	if(alloc_private(dev, sizeof(das800_private)) < 0)
-		return -ENOMEM;
-
 	dev->n_subdevices = 3;
 	if(alloc_subdevices(dev) < 0)
 		return -ENOMEM;