Re: [PATCH] drm/xe/userptr: Drop bogus static from finish in force_invalidate

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

On Thu, Jun 25, 2026 at 10:44:52PM +0000, Shuicheng Lin wrote:
> The local "finish" pointer in xe_vma_userptr_force_invalidate() is
> unconditionally written before each read, so the static storage class
> serves no purpose. Worse, it makes the variable a process-wide shared
> slot: the function's per-VM asserts do not exclude concurrent callers
> on different VMs, so two such callers can race on the slot and take
> the wrong if (finish) branch.
> 
> The function is gated by CONFIG_DRM_XE_USERPTR_INVAL_INJECT
> (developer/test option, default n), so production builds are
> unaffected.
> 
> Drop the static.
> 
> Fixes: 18c4e536959e ("drm/xe/userptr: Convert invalidation to two-pass MMU notifier")
> Assisted-by: Claude:claude-opus-4.7
> Cc: Thomas Hellström <thomas.hellstrom@linux.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_userptr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_userptr.c b/drivers/gpu/drm/xe/xe_userptr.c
> index 6761005c0b90..6f71bc66b14e 100644
> --- a/drivers/gpu/drm/xe/xe_userptr.c
> +++ b/drivers/gpu/drm/xe/xe_userptr.c
> @@ -269,7 +269,7 @@ static const struct mmu_interval_notifier_ops vma_userptr_notifier_ops = {
>   */
>  void xe_vma_userptr_force_invalidate(struct xe_userptr_vma *uvma)
>  {
> -	static struct mmu_interval_notifier_finish *finish;
> +	struct mmu_interval_notifier_finish *finish;
>  	struct xe_vm *vm = xe_vma_vm(&uvma->vma);
>  
>  	/* Protect against concurrent userptr pinning */
> -- 
> 2.43.0
>