Re: double exclamation (!!) suckage in the kernel

[David Miller]

From: "Satyam Sharma" <satyam.sharma@xxxxxxxxx>
Date: Sat, 26 May 2007 01:53:59 +0530

WHat is with multiple people asking about "!!" all of a
sudden today?

> 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?

"!!" is used in contexts where pointers might be being
tested as well as plain integers, the "!!" turns a pointer
into the equivalent integer boolean for testing.

NULL pointers become 0
non-NULL pointers become 1
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