On 04/25/2012 04:26 AM, Konstantin Khlebnikov wrote: > Sometimes we want to check some expressions correctness in compile-time without > generating extra code. "(void)(e)" does not work if expression has side-effects. > This patch introduces macro unused_expression() which helps in this situation. > > Cast to "long" required because sizeof does not work for bit-fields. > > Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> > --- > include/linux/compiler.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index 923d093..46fbda3 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -310,4 +310,6 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); > */ > #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) > > +#define unused_expression(e) ((void)(sizeof((__force long)(e)))) > + OK, bikeshedding a bit: "unused_expression()" doesn't sound like something that inhibits side effects, especially since "unused" applied to an argument or variable means "don't make a fuss over this not being used." -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
