double exclamation (!!) suckage in the kernel

["Satyam Sharma" <satyam.sharma@gmail.com>]

Hello,

Grepping through the sources I found 500+ occurrences of double
exclamation marks before identifier names (such as !!x -- I took care
to ignore occurrences of !! inside comment blocks, because there
are plenty of that sort too).

!! are to be found even in the definitions of common macros such as
likely() and unlikely(), which hundreds of eyes must have seen over
the last year or so ...

Are all these occurrences merely the debris of
s/something/!notsomething/g kind of patches or is there some
dark, unknown C / gcc wizardry I have absolutely no clue of?

Thanks,
Satyam