[BUG objtool,x86] Missing __noreturn annotation in acpi_processor_ffh_play_dead()

[Paul E. McKenney]

Hello!

My recent -next testing hits this objtool complaint:

vmlinux.o: warning: objtool: acpi_idle_play_dead+0x3c: acpi_processor_ffh_play_dead() is missing a __noreturn annotation

My attempts to silence this by adding the suggested __noreturn annotations
didn't help, and often got me compiler warnings about __noreturn functions
actually returning.  So I bisected, which converges on this innocent-looking
commit:

a7dd183f0b38 ("x86/smp: Allow calling mwait_play_dead with an arbitrary hint")

Several runs verified that this really is the commit that objtool is
complaining about.  Unfortunately, this commit does not revert cleanly.

This is from builds using clang version 19.1.5 (CentOS 19.1.5-2.el9).

Help?

							Thanx, Paul