Re: [PATCH 02/10] drm/i915/userptr: Make gup errors stickier

Joonas Lahtinen
2016-08-15T11:16:08Z

On pe, 2016-08-12 at 11:28 +0100, Chris Wilson wrote:
> Keep any error reported by the gup_worker until we are notified that the
> arena has changed (via the mmu-notifier). This has the importance of
> making two consecutive calls to i915_gem_object_get_pages() reporting
> the same error, and curtailing an loop of detecting a fault and requeueing
> a gup_worker.
>

I think this is for Mika to review.

Regards, Joonas

> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem_userptr.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
> index 57218cca7e05..be54825ef3e8 100644
> --- a/drivers/gpu/drm/i915/i915_gem_userptr.c
> +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
> @@ -542,8 +542,6 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
>   }
>   }
>   obj->userptr.work = ERR_PTR(ret);
> - if (ret)
> - __i915_gem_userptr_set_active(obj, false);
>   }
>
>   obj->userptr.workers--;
> @@ -628,15 +626,14 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
>    * to the vma (discard or cloning) which should prevent the more
>    * egregious cases from causing harm.
>    */
> - if (IS_ERR(obj->userptr.work)) {
> - /* active flag will have been dropped already by the worker */
> - ret = PTR_ERR(obj->userptr.work);
> - obj->userptr.work = NULL;
> - return ret;
> - }
> - if (obj->userptr.work)
> +
> + if (obj->userptr.work) {
>   /* active flag should still be held for the pending work */
> - return -EAGAIN;
> + if (IS_ERR(obj->userptr.work))
> + return PTR_ERR(obj->userptr.work);
> + else
> + return -EAGAIN;
> + }
>
>   /* Let the mmu-notifier know that we have begun and need cancellation */
>   ret = __i915_gem_userptr_set_active(obj, true);
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation