[PATCH] reservation: sprinkle some WARN_ON()s

[Daniel Vetter]

On Thu, Apr 07, 2016 at 08:52:56PM -0400, Rob Clark wrote:
> A bit overkill since, for example, the rcu_dereference_protected() in
> reservation_object_get_list() will WARN.  But this is much less subtle
> for folks reading the code.
> 
> v2: use reservation_object_held() instead of ww_mutex_is_locked()
> 
> Signed-off-by: Rob Clark <robdclark at gmail.com>

Doesn't seem to build here:


In file included from ./arch/arm/include/asm/bug.h:59:0,
                 from include/linux/bug.h:4,
                 from include/linux/thread_info.h:11,
                 from include/asm-generic/current.h:4,
                 from arch/arm/include/generated/asm/current.h:1,
                 from include/linux/mutex.h:13,
                 from include/linux/ww_mutex.h:17,
                 from include/linux/reservation.h:42,
                 from drivers/dma-buf/reservation.c:35:
drivers/dma-buf/reservation.c: In function ‘reservation_object_reserve_shared’:
include/linux/reservation.h:82:38: error: implicit declaration of function ‘lockdep_is_held’ [-Werror=implicit-function-declaration]
 #define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base)
                                      ^
include/asm-generic/bug.h:92:25: note: in definition of macro ‘WARN_ON’
  int __ret_warn_on = !!(condition);    \
                         ^
drivers/dma-buf/reservation.c:74:11: note: in expansion of macro ‘reservation_object_held’
  WARN_ON(!reservation_object_held(obj));

Sounds like we should include some headers from reservation.h.
-Daniel

> ---
>  drivers/dma-buf/reservation.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
> index c0bd572..439af82 100644
> --- a/drivers/dma-buf/reservation.c
> +++ b/drivers/dma-buf/reservation.c
> @@ -52,6 +52,8 @@ int reservation_object_reserve_shared(struct reservation_object *obj)
>  	struct reservation_object_list *fobj, *old;
>  	u32 max;
>  
> +	WARN_ON(!reservation_object_held(obj));
> +
>  	old = reservation_object_get_list(obj);
>  
>  	if (old && old->shared_max) {
> @@ -189,6 +191,8 @@ void reservation_object_add_shared_fence(struct reservation_object *obj,
>  {
>  	struct reservation_object_list *old, *fobj = obj->staged;
>  
> +	WARN_ON(!reservation_object_held(obj));
> +
>  	old = reservation_object_get_list(obj);
>  	obj->staged = NULL;
>  
> @@ -207,6 +211,8 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
>  	struct reservation_object_list *old;
>  	u32 i = 0;
>  
> +	WARN_ON(!reservation_object_held(obj));
> +
>  	old = reservation_object_get_list(obj);
>  	if (old)
>  		i = old->shared_count;
> -- 
> 2.5.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch