Re: [BUG] ALSA: core: pcm_memory: a possible data race in do_alloc_pages()

On 26. 06. 23 9:33, Takashi Iwai wrote:

On Mon, 26 Jun 2023 09:31:18 +0200, Tuo Li wrote:

...

Hello,

Thank you for your reply!

FWIW, the simplest fix would be something like below, just extending the mutex coverage. But it'll serialize the all calls, so it might influence on the performance, while it's the safest way.

It may be better to update total_pcm_alloc_bytes before snd_dma_alloc_dir_pages() call and decrease this value when allocation fails to allow parallel allocations. Then the mutex can be held only for the total_pcm_alloc_bytes variable update.

Eventually, total_pcm_alloc_bytes may be atomic.

Jaroslav