Re: [PATCH v3 05/12] locking/ww_mutex: Remove the __ww_mutex_lock inline wrappers

[Nicolai HÃhnle]

On 23.12.2016 11:48, Peter Zijlstra wrote:
> On Wed, Dec 21, 2016 at 07:46:33PM +0100, Nicolai HÃhnle wrote:
> > diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
> > index a5960e5..b2eaaab 100644
> > --- a/include/linux/ww_mutex.h
> > +++ b/include/linux/ww_mutex.h
> > @@ -186,11 +186,6 @@ static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
> >  #endif
> >  }
> >
> > -extern int __must_check __ww_mutex_lock(struct ww_mutex *lock,
> > -					struct ww_acquire_ctx *ctx);
> > -extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock,
> > -						      struct ww_acquire_ctx *ctx);
> > -
> >  /**
> >   * ww_mutex_lock - acquire the w/w mutex
> >   * @lock: the mutex to be acquired
> > @@ -220,10 +215,8 @@ extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock,
> >   *
> >   * A mutex acquired with this function must be released with ww_mutex_unlock.
> >   */
> > -static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
> > -{
> > -	return __ww_mutex_lock(lock, ctx);
> > -}
> > +extern int __must_check ww_mutex_lock(struct ww_mutex *lock,
> > +				      struct ww_acquire_ctx *ctx);
> >
> >  /**
> >   * ww_mutex_lock_interruptible - acquire the w/w mutex, interruptible
> > @@ -255,11 +248,8 @@ static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ct
> >   *
> >   * A mutex acquired with this function must be released with ww_mutex_unlock.
> >   */
> > -static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock,
> > -							   struct ww_acquire_ctx *ctx)
> > -{
> > -	return __ww_mutex_lock_interruptible(lock, ctx);
> > -}
> > +extern int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock,
> > +						    struct ww_acquire_ctx *ctx);
> >
> >  /**
> >   * ww_mutex_lock_slow - slowpath acquiring of the w/w mutex
> > diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
> > index a41bec2..282c6de 100644
>
> For some reason this patch appears to make lib/locking-selftest.c really
> unhappy.
>
> I get endless streams of:
>
> ../lib/locking-selftest.c: In function âww_test_fail_acquireâ:
> ../lib/locking-selftest.c:1141:6: error: void value not ignored as it ought to be
>   ret = WWL(&o, &t);
>       ^
>
> Apparently GCC gets confused about __much_check on inline functions or
> something, or I got the patch wrong.

Weird, I'm not getting that, and it makes no sense either from a quick 
glimpse of the code. Is there anything beside 
CONFIG_DEBUG_LOCKING_API_SELFTESTS I would have to enable to trigger 
this? FWIW:

$ gcc --version
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609

>