[PATCH 4.4 26/51] uio: fix dmem_region_start computation

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Viktorin <viktorin@xxxxxxxxxxxxxx>

commit 4d31a2588ae37a5d0f61f4d956454e9504846aeb upstream.

The variable i contains a total number of resources (including
IORESOURCE_IRQ). However, we want the dmem_region_start to point
after the last resource of type IORESOURCE_MEM. The original behaviour
leads (very likely) to skipping several UIO mapping regions and makes
them useless. Fix this by computing dmem_region_start from the uiomem
which points to the last used UIO mapping.

Fixes: 0a0c3b5a24bd ("Add new uio device for dynamic memory allocation")

Signed-off-by: Jan Viktorin <viktorin@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/uio/uio_dmem_genirq.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/uio/uio_dmem_genirq.c
+++ b/drivers/uio/uio_dmem_genirq.c
@@ -229,7 +229,7 @@ static int uio_dmem_genirq_probe(struct
 		++uiomem;
 	}
 
-	priv->dmem_region_start = i;
+	priv->dmem_region_start = uiomem - &uioinfo->mem[0];
 	priv->num_dmem_regions = pdata->num_dynamic_regions;
 
 	for (i = 0; i < pdata->num_dynamic_regions; ++i) {