Re: [RFC PATCH] cleanup: make scoped_guard() to be return-friendly

[Przemek Kitszel]

On 9/27/24 09:31, Dan Carpenter wrote:
> On Thu, Sep 26, 2024 at 03:41:38PM +0200, Przemek Kitszel wrote:
> > diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
> > index d9e613803df1..6b568a8a7f9c 100644
> > --- a/include/linux/cleanup.h
> > +++ b/include/linux/cleanup.h
> > @@ -168,9 +168,16 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> >   
> >   #define __guard_ptr(_name) class_##_name##_lock_ptr
> >   
> > -#define scoped_guard(_name, args...)					\
> > -	for (CLASS(_name, scope)(args),					\
> > -	     *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
> > +#define scoped_guard(_name, args...)	\
> > +	__scoped_guard_labeled(__UNIQUE_ID(label), _name, args)
> > +
> > +#define __scoped_guard_labeled(_label, _name, args...)	\
> > +	if (0)						\
> > +		_label: ;				\
> > +	else						\
> > +		for (CLASS(_name, scope)(args);		\
> > +		     __guard_ptr(_name)(&scope), 1;	\
>                                                 ^^^
> > +		     ({ goto _label; }))
> >   
>
> Remove the ", 1".  The point of the __guard_ptr() condition is for try_locks
> but the ", 1" means they always succeed.  The only try lock I can find in

You are right that the __guard_ptr() is conditional for the benefit of
try_locks. But here we have unconditional lock. And removing ", 1" part
makes compiler complaining with the very same message:
error: control reaches end of non-void function [-Werror=return-type]

so ", 1" part is on purpose and must stay there to aid compiler.

> the current tree is tsc200x_esd_work().
>
> regards,
> dan carpenter