Hi Pierre, On Mi, Sep 28, 2022 at 10:36:32 +0200, Pierre-Louis Bossart wrote: > > > On 9/27/22 14:30, Eugeniu Rosca wrote: > > Hi Pierre, > > > > On Di, Sep 27, 2022 at 09:51:46 +0200, Pierre-Louis Bossart wrote: > >> On 9/26/22 18:35, Eugeniu Rosca wrote: > >>> From: xiao jin <jin.xiao@xxxxxxxxx> > >>> > >>> After start of fe and be, fe might go to close without triggering > >>> STOP, and substream->runtime is freed. However, be is still at > >>> START state and its substream->runtime still points to the > >>> freed runtime. > >>> > >>> Later on, FE is opened/started again, and triggers STOP. > >>> snd_pcm_do_stop => dpcm_fe_dai_trigger > >>> => dpcm_fe_dai_do_trigger > >>> => dpcm_be_dai_trigger > >>> => dpcm_do_trigger > >>> => soc_pcm_trigger > >>> => skl_platform_pcm_trigger > >>> skl_platform_pcm_trigger accesses the freed old runtime data and > >>> kernel panic. > >>> > >>> The patch fixes it by assigning be_substream->runtime in > >>> dpcm_be_dai_startup when be's state is START. > >> > >> Can I ask on which kernel this patch was validated and on what platform? > > > > As shared with Czarek, > > this patch was originally extracted from the out-of-tree Intel Apollo > > Lake v4.1 KNL releases, hence it was validated on Intel ref.boards. > > > > No re-testing/re-validation has been performed on the latest vanilla. > > There's no way to predict how a patch for a kernel 4.1 - released 7 > years ago - would behave with a new kernel. If it's not tested it cannot > be merged. No disagreement here :) > > > One of the goals behind submitting the patch is getting in touch > > with the original authors, as well as the members of alsa-devel, > > to assess if the patch is still relevant. > > The only thing we could do is have more clarity on the test case and try > to reproduce it. Agreed. As soon as a test-case pops up where the patch makes a difference in the runtime behavior, you will hear back from us. > > >> > >> We've done a lot of work since last year on DPCM states, > > > > Could you please feedback if the work on the DPCM states is > > pre- or post-v5.10? > > It doesn't matter for this discussion on the upstream kernel. But yes > it's post v5.10. Thanks. This is helpful in the downstream context. > > > > >> and I wonder > >> the problem mentioned above actually exists on recent kernels. > >> > >> Specifically, if the FE is closed, I don't get how the BE is not closed > >> as well. And if this problem is found on a recent kernel, then it should > >> be seen in the AVS driver as well, no? > > > > It is totally conceivable (if not very likely) that the mainline > > advancements in the sound subsystem make this patch obsolete. > > > > I would be happy if that's the final outcome of our discussion > > (since this will allow dropping the patch in our downstream kernel). Best Regards Eugeniu
