RE: [PATCH] asm-generic: avoid __generic_cmpxchg_local warnings

[David Laight]

...
> I had another look at why the cast is even needed for atomic_cmpxchg(),
> and as Matt describes the problem here is that atomic_t contains a
> signed 'int', but cmpxchg() takes an 'unsigned long' argument, and
> converting between the two leads to a 64-bit sign-extension of
> negative 32-bit atomics.

How about:
	signed_var + 0u + 0ull;

Converts 32bit signed to 64bit unsigned without sign extension.
Compiler will throw it all away if not needed.

	David

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