AZL-83192

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (pmbus/core) Protect regulator operations with mutex

The regulator operations pmbusregulatorgetvoltage(), pmbusregulatorsetvoltage(), and pmbusregulatorlistvoltage() access PMBus registers and shared data but were not protected by the updatelock mutex. This could lead to race conditions.

However, adding mutex protection directly to these functions causes a deadlock because pmbusregulatornotify() (which calls regulatornotifiercallchain()) is often called with the mutex already held (e.g., from pmbusfault_handler()). If a regulator callback then calls one of the now-protected voltage functions, it will attempt to acquire the same mutex.

Rework pmbusregulatornotify() to utilize a worker function to send notifications outside of the mutex protection. Events are stored as atomics in a per-page bitmask and processed by the worker.

Initialize the worker and its associated data during regulator registration, and ensure it is cancelled on device removal using devmaddactionorreset().

While at it, remove the unnecessary include of linux/of.h.