[PATCH] vfio: fix crash on rmmod

[Alexey Kardashevskiy]

devtmpfs_delete_node() calls devnode() callback with mode==NULL but
vfio still tries to write there.

The patch fixes this.

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>

---

Steps to reproduce on freshly booted system with no devices given to VFIO:
modprobe vfio
rmmod vfio_iommu_spapr_tce
rmmod vfio
---
 drivers/vfio/vfio.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 523c121..259ad28 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1360,7 +1360,7 @@ static const struct file_operations vfio_device_fops = {
  */
 static char *vfio_devnode(struct device *dev, umode_t *mode)
 {
-	if (MINOR(dev->devt) == 0)
+	if (mode && (MINOR(dev->devt) == 0))
 		*mode = S_IRUGO | S_IWUGO;
 
 	return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
-- 
1.7.10.4

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