On Fri, Aug 08, 2014 at 02:52:50PM -0700, David Rientjes wrote: > On Fri, 8 Aug 2014, Bart Van Assche wrote: > > > diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h > > index 3f2867f..262ba4e 100644 > > --- a/include/linux/spinlock.h > > +++ b/include/linux/spinlock.h > > @@ -197,7 +197,13 @@ 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) > > +/* > > + * Always evaluate the 'subclass' argument to avoid that the compiler > > + * warns about set-but-not-used variables when building with > > + * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1. > > + */ > > I was hoping there was going to be a more important reason for this change > than to avoid compiler warnings, such as an example where someone is doing > spin_lock_nested(lock, subclass) and the expression for "subclass" > requires evaluation in all configs.
That would stink, having that argument have side effects. I'd call that a plain old bug that needs fixing.
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