Subject: Re: linux-next: build failure after merge of the drm-misc tree

From: Stephen Rothwell <[email-masked]>
Date: Mon, 1 Nov 2021 19:42:23 +1100

Hi all,

On Fri, 15 Oct 2021 20:26:48 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> After merging the drm-misc tree, today's linux-next build (arm
> multi_v7_defconfig) failed like this:
> 
> drivers/gpu/drm/drm_modeset_lock.c:111:29: error: conflicting types for '__stack_depot_save'
>   111 | static depot_stack_handle_t __stack_depot_save(void)
>       |                             ^~~~~~~~~~~~~~~~~~
> In file included from include/linux/page_ext.h:7,
>                  from include/linux/mm.h:25,
>                  from include/linux/kallsyms.h:13,
>                  from include/linux/bpf.h:20,
>                  from include/linux/bpf-cgroup.h:5,
>                  from include/linux/cgroup-defs.h:22,
>                  from include/linux/cgroup.h:28,
>                  from include/linux/memcontrol.h:13,
>                  from include/linux/swap.h:9,
>                  from include/linux/suspend.h:5,
>                  from include/linux/regulator/consumer.h:35,
>                  from include/linux/i2c.h:18,
>                  from include/drm/drm_crtc.h:28,
>                  from include/drm/drm_atomic.h:31,
>                  from drivers/gpu/drm/drm_modeset_lock.c:24:
> include/linux/stackdepot.h:18:22: note: previous declaration of '__stack_depot_save' was here
>    18 | depot_stack_handle_t __stack_depot_save(unsigned long *entries,
>       |                      ^~~~~~~~~~~~~~~~~~
> 
> Caused by commit
> 
>   cd06ab2fd48f ("drm/locking: add backtrace for locking contended locks without backoff")
> 
> This may only have been revealed because of another fix I have had to
> apply today.
> 
> I have applied the following patch for today.
> 
> From: Stephen Rothwell <[email-masked]>
> Date: Fri, 15 Oct 2021 20:17:52 +1100
> Subject: [PATCH] drm/locking: fix for name conflict
> 
> Fixes: cd06ab2fd48f ("drm/locking: add backtrace for locking contended locks without backoff")
> Signed-off-by: Stephen Rothwell <[email-masked]>
> ---
>  drivers/gpu/drm/drm_modeset_lock.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
> index 4d32b61fa1fd..ee36dd20900d 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -79,7 +79,7 @@
>  static DEFINE_WW_CLASS(crtc_ww_class);
>  
>  #if IS_ENABLED(CONFIG_DRM_DEBUG_MODESET_LOCK)
> -static noinline depot_stack_handle_t __stack_depot_save(void)
> +static noinline depot_stack_handle_t __drm_stack_depot_save(void)
>  {
>  	unsigned long entries[8];
>  	unsigned int n;
> @@ -108,7 +108,7 @@ static void __stack_depot_print(depot_stack_handle_t stack_depot)
>  	kfree(buf);
>  }
>  #else /* CONFIG_DRM_DEBUG_MODESET_LOCK */
> -static depot_stack_handle_t __stack_depot_save(void)
> +static depot_stack_handle_t __drm_stack_depot_save(void)
>  {
>  	return 0;
>  }
> @@ -317,7 +317,7 @@ static inline int modeset_lock(struct drm_modeset_lock *lock,
>  		ret = 0;
>  	} else if (ret == -EDEADLK) {
>  		ctx->contended = lock;
> -		ctx->stack_depot = __stack_depot_save();
> +		ctx->stack_depot = __drm_stack_depot_save();
>  	}
>  
>  	return ret;
> -- 
> 2.33.0

This has reappeared today.  I don't know what happened to the drm-misc
tree over the weeked :-(

I have reapplied the above fix.
-- 
Cheers,
Stephen Rothwell