Re: [KJ] [Patch 8/9] BUG_ON() Conversion in md/raid6main.c

[Greg KH <greg@kroah.com>]

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On Thu, Jan 26, 2006 at 02:25:07AM +0100, Eric Sesterhenn / snakebyte wrote:
> hi,
> 
> > >  this changes if() BUG(); constructs to BUG_ON() which is
> > >  cleaner and can better optimized away
> > > 
> > gcc optimizes them away if BUG() is not defined, so this is not a true
> > statement.
> 
> if BUG() is defined to nothing it still leaves the if, which must be optimized
> away by the compiler, not by the preprocessor

"gcc" is the compiler, not the preprocessor, like I stated :)

And gcc does this for you, have you looked?

> > > -		if (!list_empty(&sh->lru))
> > > -			BUG();
> > > -		if (atomic_read(&conf->active_stripes)==0)
> > > -			BUG();
> > > +		BUG_ON(!list_empty(&sh->lru));
> > > +		BUG_ON(atomic_read(&conf->active_stripes)==0);
> > 
> > Also, no, do not do this!
> > If BUG_ON() is turned off, then the logic changes here.
> 
> list_empty() just returns wheter the list is empty or not, so there is no logic
> change. and atomic_read() as far as i can see just reads the
> conf->active_stripes->counter value, so there is nothing changed somewhere
> and the logic still stays the same. Or did i miss something here?

Sorry, I was thinking that the atomic_read() was doing something there.

Anyway, these cleanups don't really change anything, at the code or
assembly level, so I don't see the need for them...

thanks,

greg k-h

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