Alternatives to /sys/kernel/debug/wakeup_sources

Hello Rafael,

Currently, Android reads wakeup sources statistics from
/sys/kernel/debug/wakeup_sources in production environment. This
information is used, for example, to report which wake lock prevents
the device from suspending.

Android userspace reading wakeup_sources is not ideal because:
- Debugfs API is not stable, i.e. Android tools built on top of it are
not guaranteed to be backward/forward compatible.
- This file requires debugfs to be mounted, which itself is
undesirable for security reasons.

To address these problems, we want to contribute a way to expose these
statistics that doesn't depend on debugfs.

Some initial thoughts/questions: Should we expose the stats in sysfs?
Or maybe implement eBPF-based solution? What do you think?

Thanks,
Tri