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SubjectRe: [PATCH RESEND] spin_lock_*(): Always evaluate second argument
On Tue, 22 Jul 2014, Andrew Morton wrote:

> > Evaluating a macro argument only if certain configuration options
> > have been selected is confusing and error-prone. Hence always
> > evaluate the second argument of spin_lock_nested() and
> > spin_lock_nest_lock().
> >
> > An intentional side effect of this patch is that it avoids that
> > the following warning is reported for netif_addr_lock_nested()
> > when building with CONFIG_DEBUG_LOCK_ALLOC=n and with W=1:
> >
> > ...
> >
> > --- a/include/linux/spinlock.h
> > +++ b/include/linux/spinlock.h
> > @@ -197,8 +197,10 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
> > _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
> > } while (0)
> > #else
> > -# define raw_spin_lock_nested(lock, subclass) _raw_spin_lock(lock)
> > -# define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
> > +# define raw_spin_lock_nested(lock, subclass) \
> > + ((void)(subclass), _raw_spin_lock(lock))
> > +# define raw_spin_lock_nest_lock(lock, nest_lock) \
> > + ((void)(nest_lock), _raw_spin_lock(lock))
> > #endif
> >
>
> Did you try converting these to static inline functions? That should
> squish the warning and makes the code nicer instead of nastier...
>

Not sure how that would be done since _raw_spin_lock isn't declared in
this scope.

Taking a second look, however, I think the patch doesn't need to modify
raw_spin_lock_nest_lock() for the problem being reported and evaluating
the parameter of type struct lockdep_map * probably is meaningless.

Bart, is it possible to just get away with the raw_spin_lock_nested()
change?


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