[alsa-devel] ASoC: atmel-pcm-dma: Leaking memory in atmel_pcm_hw_params

Bo Shen voice.shen at atmel.com
Mon Mar 18 04:59:29 CET 2013

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

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