[libcamera-devel] [PATCH] qcam: Fix ViewFinder memory leak

[Kieran Bingham]

Hi Jacopo, Laurent,

Pushed with your RB tags.

--
Kieran


On 24/09/2019 16:41, Jacopo Mondi wrote:
> Hi Kieran,
> 
> On Tue, Sep 24, 2019 at 01:00:58PM +0100, Kieran Bingham wrote:
>> Hi Laurent,
>>
>> On 24/09/2019 12:54, Laurent Pinchart wrote:
>>> Hello,
>>>
>>> On Tue, Sep 24, 2019 at 12:51:32PM +0100, Kieran Bingham wrote:
>>>> On 24/09/2019 09:16, Jacopo Mondi wrote:
>>>>> On Mon, Sep 23, 2019 at 02:22:29PM +0100, Kieran Bingham wrote:
>>>>>> When setting the format on the ViewFinder, a new image_ is allocated.
>>>>>> Any change in format deletes the existing allocation, but it is not
>>>>>> cleaned up on shutdown:
>>>>>>
>>>>>> Direct leak of 32 byte(s) in 1 object(s) allocated from:
>>>>>>     #0 0x7f0bf8a7e17f in operator new(unsigned long) (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x10e17f)
>>>>>>     #1 0x564c7205f7b0 in ViewFinder::setFormat(unsigned int, unsigned int, unsigned int) ../src/qcam/viewfinder.cpp:43
>>>>>>     #2 0x564c71fec467 in MainWindow::startCapture() ../src/qcam/main_window.cpp:152
>>>>>>     #3 0x564c71fe6c1a in MainWindow::MainWindow(libcamera::CameraManager*, OptionsParser::Options const&) ../src/qcam/main_window.cpp:40
>>>>>>     #4 0x564c71fdf133 in main ../src/qcam/main.cpp:76
>>>>>>     #5 0x7f0bf5944b6a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x26b6a)
>>>>>>
>>>>>> Provide a ViewFinder destructor, and delete the allocation as
>>>>>> appropriate.
>>>>>
>>>>> Good catch, but I don't see where the viewfinder gets destroyed in
>>>>> main_window.cpp. How does the newly added destructor gets called?
>>>>
>>>> Intriguing, the addition of the destructor made the LeakSanitizer
>>>> warning go away, however I believe you are right. There is no explicit
>>>> call to delete the ViewFinder which is created as part of the MainWindow.
>>>>
>>>> I'll add this, and respin a v2.
>>>
>>> No need to, https://doc.qt.io/qt-5/qobject.html#dtor.QObject
> 
> With the trick pointed out by Laurent clarifying my concerns:
> Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> 
> Thanks
>   j
>>
>>
>> Aha - ok so because it's constructed with 'this' passed in the
>> destruction is linked:
>>         viewfinder_ = new ViewFinder(this);
>>
>> That explains why just cleaning up the QImage leak was enough.
>>
>> I'll stick with V1 then.
>>
>> Regards
>>
>> Kieran
>>
>>
>>>
>>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>>>
>>>>>> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>>>>> ---
>>>>>>  src/qcam/viewfinder.cpp | 5 +++++
>>>>>>  src/qcam/viewfinder.h   | 1 +
>>>>>>  2 files changed, 6 insertions(+)
>>>>>>
>>>>>> diff --git a/src/qcam/viewfinder.cpp b/src/qcam/viewfinder.cpp
>>>>>> index 224a227ddd5b..98a8ab68e5f6 100644
>>>>>> --- a/src/qcam/viewfinder.cpp
>>>>>> +++ b/src/qcam/viewfinder.cpp
>>>>>> @@ -16,6 +16,11 @@ ViewFinder::ViewFinder(QWidget *parent)
>>>>>>  {
>>>>>>  }
>>>>>>
>>>>>> +ViewFinder::~ViewFinder()
>>>>>> +{
>>>>>> +	delete image_;
>>>>>> +}
>>>>>> +
>>>>>>  void ViewFinder::display(const unsigned char *raw, size_t size)
>>>>>>  {
>>>>>>  	converter_.convert(raw, size, image_);
>>>>>> diff --git a/src/qcam/viewfinder.h b/src/qcam/viewfinder.h
>>>>>> index c9ca98913e05..33bdb1460f84 100644
>>>>>> --- a/src/qcam/viewfinder.h
>>>>>> +++ b/src/qcam/viewfinder.h
>>>>>> @@ -17,6 +17,7 @@ class ViewFinder : public QLabel
>>>>>>  {
>>>>>>  public:
>>>>>>  	ViewFinder(QWidget *parent);
>>>>>> +	~ViewFinder();
>>>>>>
>>>>>>  	int setFormat(unsigned int format, unsigned int width,
>>>>>>  		      unsigned int height);
>>>
>>
>> --
>> Regards
>> --
>> Kieran

-- 
Regards
--
Kieran