As pointed out by Dan carpenter for the similar pcmuio driver, there is
no need to check the pointer passed to `kfree()`, so remove that check
from `pcmmio_detach()`.

Also, check the `devpriv` (`dev->private`) pointer once, outside the
`for` loop.

Signed-off-by: Ian Abbott <abbo...@mev.co.uk>
Cc: Dan Carpenter <dan.carpen...@oracle.com>
---
v2: Removed a duplicate check of `devpriv`.  Changed the patch subject
line from "staging: comedi: pcmmio: fix possible NULL deref on detach"
and changed the inaccurate description as there was no bug.
---
 drivers/staging/comedi/drivers/pcmmio.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/comedi/drivers/pcmmio.c 
b/drivers/staging/comedi/drivers/pcmmio.c
index aa3c030..574443d 100644
--- a/drivers/staging/comedi/drivers/pcmmio.c
+++ b/drivers/staging/comedi/drivers/pcmmio.c
@@ -1156,12 +1156,13 @@ static void pcmmio_detach(struct comedi_device *dev)
        struct pcmmio_private *devpriv = dev->private;
        int i;
 
-       for (i = 0; i < MAX_ASICS; ++i) {
-               if (devpriv && devpriv->asics[i].irq)
-                       free_irq(devpriv->asics[i].irq, dev);
-       }
-       if (devpriv && devpriv->sprivs)
+       if (devpriv) {
+               for (i = 0; i < MAX_ASICS; ++i) {
+                       if (devpriv->asics[i].irq)
+                               free_irq(devpriv->asics[i].irq, dev);
+               }
                kfree(devpriv->sprivs);
+       }
        comedi_legacy_detach(dev);
 }
 
-- 
1.8.3.2

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