Messages in this thread | | | Date | Fri, 8 Aug 2014 14:52:50 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH v3] spin_lock_nested(): Always evaluate second argument |
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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.
> +# define raw_spin_lock_nested(lock, subclass) \ > + _raw_spin_lock(((void)(subclass), (lock))) > # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock) > #endif >
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