Merge tag 'smp-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git...

Pull SMP core updates from Thomas Gleixner:

 - Switch smp_call_on_cpu() to user system_percpu_wq instead of
   system_wq a part of the ongoing workqueue restructuring

 - Improve the CSD-lock diagnostics for smp_call_function_single() to
   provide better debug mechanisms on weakly ordered systems.

 - Cache the current CPU number once in smp_call_function*() instead of
   retrieving it over and over.

 - Add missing kernel-doc comments all over the place

* tag 'smp-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smp: Use system_percpu_wq instead of system_wq
  smp: Improve smp_call_function_single() CSD-lock diagnostics
  smp: Get this_cpu once in smp_call_function
  smp: Add missing kernel-doc comments