Re: [PATCH] drm/xe/userptr: Stub notifier_lock helpers when DRM_GPUSVM=n

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Jun 30, 2026 at 07:22:21PM +0000, Shuicheng Lin wrote:
> When CONFIG_DRM_GPUSVM=n (e.g. um-allyesconfig), the only caller of
> xe_pt_svm_userptr_notifier_lock() is compiled out, triggering:
> 
>   drivers/gpu/drm/xe/xe_pt.c:1418:13: warning:
>     'xe_pt_svm_userptr_notifier_lock' defined but not used
>     [-Wunused-function]
> 
> The helpers cannot simply be removed in this case: the matching
> xe_pt_svm_userptr_notifier_unlock() is also referenced from
> xe_pt_update_ops_run(), which lives outside any DRM_GPUSVM ifdef and is
> gated only at runtime by pt_update_ops->needs_svm_lock. The symbol must
> exist in all builds.
> 
> Provide empty static inline stubs for !DRM_GPUSVM, matching the pattern
> used by xe_svm_notifier_lock()/_unlock() in xe_svm.h.
> 
> Fixes: 80ccbd97ffee ("drm/xe/userptr: Hold notifier_lock for write on inject test path")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202606302210.QqcLbOEN-lkp@intel.com/
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_pt.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> index 4f0f438d6b9b..20b9611e993b 100644
> --- a/drivers/gpu/drm/xe/xe_pt.c
> +++ b/drivers/gpu/drm/xe/xe_pt.c
> @@ -1406,6 +1406,7 @@ static int xe_pt_pre_commit(struct xe_migrate_pt_update *pt_update)
>  				     pt_update_ops, rftree);
>  }
>  
> +#if IS_ENABLED(CONFIG_DRM_GPUSVM)
>  /*
>   * Acquire/release the svm notifier_lock around xe_pt_svm_userptr_pre_commit()
>   * and the matching late release in xe_pt_update_ops_run(). Read mode by
> @@ -1432,6 +1433,10 @@ static void xe_pt_svm_userptr_notifier_unlock(struct xe_vm *vm)
>  	xe_svm_notifier_unlock(vm);
>  #endif
>  }
> +#else
> +static inline void xe_pt_svm_userptr_notifier_lock(struct xe_vm *vm) { }
> +static inline void xe_pt_svm_userptr_notifier_unlock(struct xe_vm *vm) { }
> +#endif
>  
>  #if IS_ENABLED(CONFIG_DRM_GPUSVM)
>  #ifdef CONFIG_DRM_XE_USERPTR_INVAL_INJECT
> -- 
> 2.43.0
>