On 9/12/23 02:10, Péter Ujfalusi wrote:
On 12/09/2023 03:25, Pierre-Louis Bossart wrote:
What we have atm: snd_sof_probe - might be called from wq snd_sof_remove - might be called from wq (cleans up the snd_sof_probe step)
I don't think it's correct, snd_sof_remove cannot be called from a wq. The device core knows nothing about workqueues.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/soun...
it is called on the error path of sof_probe_continue(), which can be run in a workque.
We want a callbacks for hardware/device probing, right, split the snd_sof_probe (and remove) to be able to support a sane level of deferred probing support.
With that in mind: snd_sof_device_probe - Not called from wq (to handle deferred probing) snd_sof_probe - might be called from wq
snd_sof_remove - might be called from wq (cleans up the snd_sof_probe step) snd_sof_device_remove - Not called from wq (to up the snd_sof_device_probe step)
Naming option: s/device/hardware
I like the 'device' hint since it's directly related to the device (or subsystem) callbacks.
However, I think the snd_sof_device_remove itself is redundant and we might not need it at all as in case we have wq and there is a failure in there we do want to release resources as much as possible. The module will be kept loaded (no deferred handling in wq) and that might block PM, other devices to behave correctly. Iow, if the wq has failure we should do a cleanup to the best effort to reach a level like the driver is not even loaded.
If we have a failure in a workqueue used for probe, then we have to clean-up everything since nothing in the device core will do so for us.
Yes, this makes the snd_sof_device_remove() redundant or at least the definition of it is no longer a mirror of snd_sof_device_probe():
snd_sof_device_remove - might be called from wq (cleans up the snd_sof_device_probe step)
Any failure in sof_probe_continue() should execute the snd_sof_device_remove(), snd_sof_remove() is only involved after the snd_sof_probe() have returned with success.
I think this makes actually makes sense and it is well defined. On module remove we need to take into account the case when we have failed in wq similarly as we do currently (the resources have been freed up already).
Agree, I stand corrected, thanks Peter.