[PATCH v3 30/31] staging: comedi: ni_pcidio: request_irq() before setting up subdevices

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Do the request_irq() before setting up the subdevices. Only hook up
the command support of the irq was sucessfully requested.

Note that, because of the IRQF_SHARED flag, nidio_interrupt() _may_
be called before the device is ready and the subdevices are setup.
This condition is handled by the (!dev->attached) sanity check. The
'dev->read_subdev' pointer might not be valid at this point so there
is an extra check to get the pointer to the comedi_async buffer.

Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
v3: fix a possible dereference of 's' in nido_interrupt()

 drivers/staging/comedi/drivers/ni_pcidio.c | 40 +++++++++++++++---------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/drivers/staging/comedi/drivers/ni_pcidio.c b/drivers/staging/comedi/drivers/ni_pcidio.c
index 30c46a3..8f1b64d 100644
--- a/drivers/staging/comedi/drivers/ni_pcidio.c
+++ b/drivers/staging/comedi/drivers/ni_pcidio.c
@@ -385,7 +385,7 @@ static irqreturn_t nidio_interrupt(int irq, void *d)
 	struct comedi_device *dev = d;
 	struct nidio96_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
-	struct comedi_async *async = s->async;
+	struct comedi_async *async = s ? s->async : NULL;
 	struct mite_struct *mite = devpriv->mite;
 
 	/* int i, j; */
@@ -1011,6 +1011,14 @@ static int nidio_auto_attach(struct comedi_device *dev,
 
 	nidio_reset_board(dev);
 
+	irq = mite_irq(devpriv->mite);
+	if (irq) {
+		ret = request_irq(irq, nidio_interrupt, IRQF_SHARED,
+				  dev->board_name, dev);
+		if (ret == 0)
+			dev->irq = irq;
+	}
+
 	ret = comedi_alloc_subdevices(dev, 1);
 	if (ret)
 		return ret;
@@ -1019,31 +1027,23 @@ static int nidio_auto_attach(struct comedi_device *dev,
 		 readb(devpriv->mite->daq_io_addr + Chip_Version));
 
 	s = &dev->subdevices[0];
-
-	dev->read_subdev = s;
 	s->type = COMEDI_SUBD_DIO;
-	s->subdev_flags =
-		SDF_READABLE | SDF_WRITABLE | SDF_LSAMPL | SDF_PACKED |
-		SDF_CMD_READ;
+	s->subdev_flags = SDF_READABLE | SDF_WRITABLE | SDF_LSAMPL | SDF_PACKED;
 	s->n_chan = 32;
 	s->range_table = &range_digital;
 	s->maxdata = 1;
 	s->insn_config = &ni_pcidio_insn_config;
 	s->insn_bits = &ni_pcidio_insn_bits;
-	s->do_cmd = &ni_pcidio_cmd;
-	s->do_cmdtest = &ni_pcidio_cmdtest;
-	s->cancel = &ni_pcidio_cancel;
-	s->len_chanlist = 32;	/* XXX */
-	s->buf_change = &ni_pcidio_change;
-	s->async_dma_dir = DMA_BIDIRECTIONAL;
-	s->poll = &ni_pcidio_poll;
-
-	irq = mite_irq(devpriv->mite);
-	if (irq) {
-		ret = request_irq(irq, nidio_interrupt, IRQF_SHARED,
-				  dev->board_name, dev);
-		if (ret == 0)
-			dev->irq = irq;
+	if (dev->irq) {
+		dev->read_subdev = s;
+		s->subdev_flags |= SDF_CMD_READ;
+		s->async_dma_dir = DMA_BIDIRECTIONAL;
+		s->len_chanlist = s->n_chan;
+		s->do_cmd = ni_pcidio_cmd;
+		s->do_cmdtest = ni_pcidio_cmdtest;
+		s->cancel = ni_pcidio_cancel;
+		s->poll = ni_pcidio_poll;
+		s->buf_change = ni_pcidio_change;
 	}
 
 	return 0;
-- 
1.8.4.4

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