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 <hswee...@visionengravers.com>
Cc: Ian Abbott <abbo...@mev.co.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
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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