Re: [tip:core/urgent] WARN_ON_SMP(): Allow use in if() statementson UP

[Steven Rostedt]

On Fri, 2011-03-25 at 09:45 -0700, Linus Torvalds wrote:
> On Fri, Mar 25, 2011 at 3:48 AM, tip-bot for Steven Rostedt
> <srostedt@xxxxxxxxxx> wrote:
> > -# define WARN_ON_SMP(x)                        do { } while (0)
> > +# define WARN_ON_SMP(x)                        ({0;})
> 
> That's a VERY odd way of writing "0".
> 
> Am I missing something subtle?

I thought about using "0", but when WARN_ON_SMP() is used outside of an
if statement, it turns into:

	0;

Which seems strange to me. Thus the ({0;}) was basically a way to state
that this is also a function and not just a 0 value.

Also, a quick test shows that

	0;

gives the warning:

	"warning: statement with no effect"

-- Steve


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