Re: [PATCH v2] ALSA: pcmtest: stop timer in the hw_free callback

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On 12/6/23 16:59, Takashi Iwai wrote:
On Wed, 06 Dec 2023 16:10:46 +0100,
Ivan Orlov wrote:

Stop timer in the 'hw_free' callback instead of the 'close' callback
since we want the timer to be stopped before the DMA buffer is released.
Otherwise, it could trigger a kernel panic in some circumstances, for
instance when the DMA buffer is already released but the timer callback
is still running.

You can't call timer_shutdown_sync() at hw_free.  The PCM stream is
still there and you can re-setup via hw_params without closing.  But,
after timer_shutdown_sync(), the timer instance must not be used any
longer.

A more proper way would be to call timer_delete() (no sync) at trigger
STOP, then call timer_delete_sync() at sync_stop op in addition.  This
assures the immediate stop and the sync before changing to another PCM
state.

timer_shutdown_sync() can be kept at the close op to be sure.


thanks,

Takashi


Hi Takashi,

Thanks a lot for the review, sounds reasonable, I'll make suggested changes and send the version 3 :)

--
Kind regards,
Ivan Orlov





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