media: omap3isp: fix unbalanced dma_iommu_mapping

Message ID 20180312165207.12436-1-s-anna@ti.com
State New
Headers show
Series
  • media: omap3isp: fix unbalanced dma_iommu_mapping
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Commit Message

Suman Anna March 12, 2018, 4:52 p.m.
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 <pavel@ucw.cz>
Signed-off-by: Suman Anna <s-anna@ti.com>

Tested-by: Pavel Machek <pavel@ucw.cz>

---
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(-)

-- 
2.16.2

Comments

Suman Anna March 13, 2018, 3:47 p.m. | #1
Hi Sakari,

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

> 

> Thanks for the patch.

> 

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

>> 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 <pavel@ucw.cz>

>> Signed-off-by: Suman Anna <s-anna@ti.com>

>> Tested-by: Pavel Machek <pavel@ucw.cz>

>> ---

>> 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.

regards
Suman

> 

> After fixing that you can add:

> 

> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>

> 

>>  	}

>>  

>>  	return 0;

>>  

>> +error_attach:

>> +	arm_iommu_release_mapping(isp->mapping);

>> +	isp->mapping = NULL;

>>  error:

>> -	isp_detach_iommu(isp);

>>  	return ret;

>>  }

>>  

>>

>
Sakari Ailus March 14, 2018, 9:28 a.m. | #2
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:

> > Hi Suman,

> > 

> > Thanks for the patch.

> > 

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

> >> 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 <pavel@ucw.cz>

> >> Signed-off-by: Suman Anna <s-anna@ti.com>

> >> Tested-by: Pavel Machek <pavel@ucw.cz>

> >> ---

> >> 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@iki.fi

Patch

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;
 	}
 
 	return 0;
 
+error_attach:
+	arm_iommu_release_mapping(isp->mapping);
+	isp->mapping = NULL;
 error:
-	isp_detach_iommu(isp);
 	return ret;
 }