[PATCH v2] libcamera: software_isp: Replace malloc() with std::vector<>

[Milan Zamazal]

Kieran Bingham <kieran.bingham at ideasonboard.com> writes:

> Quoting Laurent Pinchart (2024-08-04 14:36:05)
>> libcamera is implemented in C++, use std::vector<> to manage the
>> dynamically allocated line buffers instead of malloc() and free(). This
>
>> simplifies the code and improves memory safety by ensuring no allocation
>> will be leaked.
>> 
>> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> ---
>> Changes since v1:
>> 
>> - Use std::vector instead of new[]() and delete[]()
>> ---
>>  src/libcamera/software_isp/debayer_cpu.cpp | 31 +++++++++-------------
>>  src/libcamera/software_isp/debayer_cpu.h   |  2 +-
>>  2 files changed, 13 insertions(+), 20 deletions(-)
>> 
>> diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp
>> index f8d2677d657a..077f7f4bc45b 100644
>> --- a/src/libcamera/software_isp/debayer_cpu.cpp
>> +++ b/src/libcamera/software_isp/debayer_cpu.cpp
>> @@ -49,16 +49,9 @@ DebayerCpu::DebayerCpu(std::unique_ptr<SwStatsCpu> stats)
>>         /* Initialize color lookup tables */
>>         for (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++)
>>                 red_[i] = green_[i] = blue_[i] = i;
>> -
>> -       for (unsigned int i = 0; i < kMaxLineBuffers; i++)
>> -               lineBuffers_[i] = nullptr;
>>  }
>>  
>> -DebayerCpu::~DebayerCpu()
>> -{
>> -       for (unsigned int i = 0; i < kMaxLineBuffers; i++)
>> -               free(lineBuffers_[i]);
>> -}
>> +DebayerCpu::~DebayerCpu() = default;
>>  
>>  #define DECLARE_SRC_POINTERS(pixel_t)                            \
>>         const pixel_t *prev = (const pixel_t *)src[0] + xShift_; \
>> @@ -526,13 +519,10 @@ int DebayerCpu::configure(const StreamConfiguration &inputCfg,
>>         lineBufferPadding_ = inputConfig_.patternSize.width * inputConfig_.bpp / 8;
>>         lineBufferLength_ = window_.width * inputConfig_.bpp / 8 +
>>                             2 * lineBufferPadding_;
>> -       for (unsigned int i = 0;
>> -            i < (inputConfig_.patternSize.height + 1) && enableInputMemcpy_;
>> -            i++) {
>> -               free(lineBuffers_[i]);
>> -               lineBuffers_[i] = (uint8_t *)malloc(lineBufferLength_);
>> -               if (!lineBuffers_[i])
>> -                       return -ENOMEM;
>> +
>> +       if (enableInputMemcpy_) {
>> +               for (unsigned int i = 0; i <= inputConfig_.patternSize.height; i++)
>> +                       lineBuffers_[i].resize(lineBufferLength_);
>
> that's easier.
>
> I don't think the previous implementation was doing it, but should any
> following lines be resized to 0 if the configuration shrinks?
>
> Worst case, this could grow to full allocation, then the later lines
> would remain allocated indefinitely on any system with a long running
> camera manager (i.e. pipewire). The memory wouldn't be lost, as it would
> be released when the camera manager is destroyed, but the memory
> wouldn't be usable...

Can the Bayer pattern actually change when changing the configuration?

> Could be a patch on top as the previous implementation didn't do this
> and it's just a conversion patch here.
>
> So I think this patch still steps in a good way forwards:
>
>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
>
>>         }
>>  
>>         measuredFrames_ = 0;
>> @@ -587,9 +577,10 @@ void DebayerCpu::setupInputMemcpy(const uint8_t *linePointers[])
>>                 return;
>>  
>>         for (unsigned int i = 0; i < patternHeight; i++) {
>> -               memcpy(lineBuffers_[i], linePointers[i + 1] - lineBufferPadding_,
>> +               memcpy(lineBuffers_[i].data(),
>> +                      linePointers[i + 1] - lineBufferPadding_,
>>                        lineBufferLength_);
>> -               linePointers[i + 1] = lineBuffers_[i] + lineBufferPadding_;
>> +               linePointers[i + 1] = lineBuffers_[i].data() + lineBufferPadding_;
>>         }
>>  
>>         /* Point lineBufferIndex_ to first unused lineBuffer */
>> @@ -614,9 +605,11 @@ void DebayerCpu::memcpyNextLine(const uint8_t *linePointers[])
>>         if (!enableInputMemcpy_)
>>                 return;
>>  
>> -       memcpy(lineBuffers_[lineBufferIndex_], linePointers[patternHeight] - lineBufferPadding_,
>> +       memcpy(lineBuffers_[lineBufferIndex_].data(),
>> +              linePointers[patternHeight] - lineBufferPadding_,
>>                lineBufferLength_);
>> -       linePointers[patternHeight] = lineBuffers_[lineBufferIndex_] + lineBufferPadding_;
>> +       linePointers[patternHeight] = lineBuffers_[lineBufferIndex_].data()
>> +                                   + lineBufferPadding_;
>>  
>>         lineBufferIndex_ = (lineBufferIndex_ + 1) % (patternHeight + 1);
>>  }
>> diff --git a/src/libcamera/software_isp/debayer_cpu.h b/src/libcamera/software_isp/debayer_cpu.h
>> index 1dac64351f1d..8237a64be733 100644
>> --- a/src/libcamera/software_isp/debayer_cpu.h
>> +++ b/src/libcamera/software_isp/debayer_cpu.h
>> @@ -146,7 +146,7 @@ private:
>>         DebayerInputConfig inputConfig_;
>>         DebayerOutputConfig outputConfig_;
>>         std::unique_ptr<SwStatsCpu> stats_;
>> -       uint8_t *lineBuffers_[kMaxLineBuffers];
>> +       std::vector<uint8_t> lineBuffers_[kMaxLineBuffers];
>>         unsigned int lineBufferLength_;
>>         unsigned int lineBufferPadding_;
>>         unsigned int lineBufferIndex_;
>> 
>> base-commit: 19bbca3c0b376ba0183f5db53472c8c46cd402b5
>> -- 
>> Regards,
>> 
>> Laurent Pinchart
>>