[PATCH] media: omap3isp: fix unbalanced dma_iommu_mapping

On Tue, Mar 13, 2018 at 10:47:08AM -0500, Suman Anna wrote:

Hi Sakari,

On 03/13/2018 06:14 AM, Sakari Ailus wrote:

quoted

Hi Suman,

Thanks for the patch.

On Mon, Mar 12, 2018 at 11:52:07AM -0500, Suman Anna wrote:

quoted

The OMAP3 ISP driver manages its MMU mappings through the IOMMU-aware
ARM DMA backend. The current code creates a dma_iommu_mapping and
attaches this to the ISP device, but never detaches the mapping in
either the probe failure paths or the driver remove path resulting
in an unbalanced mapping refcount and a memory leak. Fix this properly.

Reported-by: Pavel Machek <redacted>
Signed-off-by: Suman Anna <redacted>
Tested-by: Pavel Machek <redacted>
---
Hi Mauro, Laurent,

This fixes an issue reported by Pavel and discussed on this
thread,
https://marc.info/?l=linux-omap&m=152051945803598&w=2

Posting this again to the appropriate lists.

regards
Suman

 drivers/media/platform/omap3isp/isp.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/omap3isp/isp.c b/drivers/media/platform/omap3isp/isp.c
index 8eb000e3d8fd..c7d667bfc2af 100644
--- a/drivers/media/platform/omap3isp/isp.c
+++ b/drivers/media/platform/omap3isp/isp.c

@@ -1945,6 +1945,7 @@ static int isp_initialize_modules(struct isp_device *isp)
 
 static void isp_detach_iommu(struct isp_device *isp)
 {
+	arm_iommu_detach_device(isp->dev);
 	arm_iommu_release_mapping(isp->mapping);
 	isp->mapping = NULL;
 }

@@ -1971,13 +1972,15 @@ static int isp_attach_iommu(struct isp_device *isp)
 	ret = arm_iommu_attach_device(isp->dev, mapping);
 	if (ret < 0) {
 		dev_err(isp->dev, "failed to attach device to VA mapping\n");
-		goto error;
+		goto error_attach;

Instead of changing the label here, could you return immediately where the
previous point of error handling is? No need to add another label.

Yeah, I debated about this while doing the patch, and chose to retain
the previous common return on the error paths. There are only 2 error
paths, so didn't want to mix them up. If you still prefer the mixed
style, I can post a v2.

Yes, please. In general if you only need return a value, a label isn't
needed for that even if goto + labels would be otherwise used for error
handling.

-- 
Sakari Ailus
e-mail: sakari.ailus at iki.fi