Re: drm/ttm/tests: Fix build failure on PREEMPT_RT

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2026-02-26 at 16:12 +0100, Maarten Lankhorst wrote:
> Fix a compile error in the kunit tests when CONFIG_PREEMPT_RT is
> enabled, and the normal mutex is converted into a rtmutex.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes:
> https://lore.kernel.org/oe-kbuild-all/202602261547.3bM6yVAS-lkp@intel.com/
> Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
> ---
>  drivers/gpu/drm/ttm/tests/ttm_bo_test.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
> b/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
> index d468f83220720..2ba5ddf2b1c9e 100644
> --- a/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
> +++ b/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
> @@ -222,13 +222,13 @@ static void ttm_bo_reserve_interrupted(struct
> kunit *test)
>  		KUNIT_FAIL(test, "Couldn't create ttm bo reserve
> task\n");
>  
>  	/* Take a lock so the threaded reserve has to wait */
> -	mutex_lock(&bo->base.resv->lock.base);
> +	ww_mutex_lock(&bo->base.resv->lock, NULL);

There is this comment in include/linux/dma-resv.h:dma_resv:lock :

* Update side lock. Don't use directly, instead use the wrapper
* functions like dma_resv_lock() and dma_resv_unlock().

BR,
Jouni Högander

>  
>  	wake_up_process(task);
>  	msleep(20);
>  	err = kthread_stop(task);
>  
> -	mutex_unlock(&bo->base.resv->lock.base);
> +	ww_mutex_unlock(&bo->base.resv->lock);
>  
>  	KUNIT_ASSERT_EQ(test, err, -ERESTARTSYS);
>  }