Hi Greg and Sasha,

Please find attached backports of commit 1139aeb1c521 ("smp: Fix
smp_call_function_single_async prototype") upstream, which resolves a
serious looking clang warning seen across several different builds. It
has been build tested with gcc and clang for x86_64 defconfig and
allmodconfig.

Please let me know if there are any problems.

Cheers,
Nathan