[alsa-devel] ASoC: atmel-pcm-dma: Leaking memory in atmel_pcm_hw_params
Hi,
The dmaengine based pcm driver for atmel calls snd_dmaengine_pcm_open from it's hw_params callback. There is nothing preventing an application calling hw_params more than once. snd_dmaengine_pcm_open allocates a new prtd struct each time it gets called. So in case hw_params is called multiple times we leak memory here.
Is there any specific reason why snd_dmaengine_pcm_open() needs to be called from the hw_params callback and why it can't be called from the open callback? The filter function depends on the data returned by snd_soc_dai_get_dma_data(), but as far as I can see the DAI driver calls snd_soc_dai_set_dma_data() from its startup() callback, so the data is available in the PCM drivers open callback.
- Lars
Hi Lars,
On 3/17/2013 22:39, Lars-Peter Clausen wrote:
Hi,
The dmaengine based pcm driver for atmel calls snd_dmaengine_pcm_open from it's hw_params callback. There is nothing preventing an application calling hw_params more than once. snd_dmaengine_pcm_open allocates a new prtd struct each time it gets called. So in case hw_params is called multiple times we leak memory here.
I use alsa utils and don't meet this issue. Please point out which software you use meet this issue.
Is there any specific reason why snd_dmaengine_pcm_open() needs to be called from the hw_params callback and why it can't be called from the open callback?
This is because dma data setting and usage.
The filter function depends on the data returned by
snd_soc_dai_get_dma_data(), but as far as I can see the DAI driver calls snd_soc_dai_set_dma_data() from its startup() callback, so the data is available in the PCM drivers open callback.
Have you test this yet?
- Lars
Best Regards, Bo Shen
On 03/18/2013 04:59 AM, Bo Shen wrote:
Hi Lars,
On 3/17/2013 22:39, Lars-Peter Clausen wrote:
Hi,
The dmaengine based pcm driver for atmel calls snd_dmaengine_pcm_open from it's hw_params callback. There is nothing preventing an application calling hw_params more than once. snd_dmaengine_pcm_open allocates a new prtd struct each time it gets called. So in case hw_params is called multiple times we leak memory here.
I use alsa utils and don't meet this issue. Please point out which software you use meet this issue.
I found the issue by looking at the code, but I think any application using the oss compatibility layer of ALSA will trigger this.
Is there any specific reason why snd_dmaengine_pcm_open() needs to be called from the hw_params callback and why it can't be called from the open callback?
This is because dma data setting and usage.
The filter function depends on the data returned by
snd_soc_dai_get_dma_data(), but as far as I can see the DAI driver calls snd_soc_dai_set_dma_data() from its startup() callback, so the data is available in the PCM drivers open callback.
Have you test this yet?
I don't have the hardware. I just looked at the code again, and it looks like I must have misread it the first time. snd_soc_dai_set_dma_data() is called from the DAI drivers hwparams callback. But the data that gets passed to snd_soc_dai_set_dma_data() doesn't really depend on anything that's only available in the hwparams callback. So the snd_soc_dai_set_dma_data() could easily be move to the DAI driver startup() callback.
- Lars
Hi Lars,
On 3/18/2013 23:36, Lars-Peter Clausen wrote:
On 03/18/2013 04:59 AM, Bo Shen wrote:
Hi Lars,
On 3/17/2013 22:39, Lars-Peter Clausen wrote:
Hi,
The dmaengine based pcm driver for atmel calls snd_dmaengine_pcm_open from it's hw_params callback. There is nothing preventing an application calling hw_params more than once. snd_dmaengine_pcm_open allocates a new prtd struct each time it gets called. So in case hw_params is called multiple times we leak memory here.
I use alsa utils and don't meet this issue. Please point out which software you use meet this issue.
I found the issue by looking at the code, but I think any application using the oss compatibility layer of ALSA will trigger this.
Thanks for this information.
Is there any specific reason why snd_dmaengine_pcm_open() needs to be called from the hw_params callback and why it can't be called from the open callback?
This is because dma data setting and usage.
The filter function depends on the data returned by
snd_soc_dai_get_dma_data(), but as far as I can see the DAI driver calls snd_soc_dai_set_dma_data() from its startup() callback, so the data is available in the PCM drivers open callback.
Have you test this yet?
I don't have the hardware. I just looked at the code again, and it looks like I must have misread it the first time. snd_soc_dai_set_dma_data() is called from the DAI drivers hwparams callback. But the data that gets passed to snd_soc_dai_set_dma_data() doesn't really depend on anything that's only available in the hwparams callback. So the snd_soc_dai_set_dma_data() could easily be move to the DAI driver startup() callback.
I will implement this, and send patch for this.
Thanks again.
- Lars
Best Regards, Bo Shen
participants (2)
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Bo Shen -
Lars-Peter Clausen