Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 68d6c840 authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
Browse files

drm/i915: Only update the current userptr worker 



The userptr worker allows for a slight race condition where upon there
may two or more threads calling get_user_pages for the same object. When
we have the array of pages, then we serialise the update of the object.
However, the worker should only overwrite the obj->userptr.work pointer
if and only if it is the active one. Currently we clear it for a
secondary worker with the effect that we may rarely force a second
lookup.

v2: Rebase and rename a variable to avoid 80cols
v3: Mention v2

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 24dfd073

drivers/gpu/drm/i915/i915_gem_userptr.c

+16 −16
Original line number Diff line number Diff line
@@ -571,25 +571,25 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) 
	struct get_pages_work *work = container_of(_work, typeof(*work), work);

	struct drm_i915_gem_object *obj = work->obj;

	struct drm_device *dev = obj->base.dev;

	const int num_pages = obj->base.size >> PAGE_SHIFT;

	const int npages = obj->base.size >> PAGE_SHIFT;

	struct page **pvec;

	int pinned, ret;



	ret = -ENOMEM;

	pinned = 0;



	pvec = kmalloc(num_pages*sizeof(struct page *),

	pvec = kmalloc(npages*sizeof(struct page *),

		       GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);

	if (pvec == NULL)

		pvec = drm_malloc_ab(num_pages, sizeof(struct page *));

		pvec = drm_malloc_ab(npages, sizeof(struct page *));

	if (pvec != NULL) {

		struct mm_struct *mm = obj->userptr.mm->mm;



		down_read(&mm->mmap_sem);

		while (pinned < num_pages) {

		while (pinned < npages) {

			ret = get_user_pages(work->task, mm,

					     obj->userptr.ptr + pinned * PAGE_SIZE,

					     num_pages - pinned,

					     npages - pinned,

					     !obj->userptr.read_only, 0,

					     pvec + pinned, NULL);

			if (ret < 0)
@@ -601,20 +601,20 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) 
	}



	mutex_lock(&dev->struct_mutex);

	if (obj->userptr.work != &work->work) {

		ret = 0;

	} else if (pinned == num_pages) {

		ret = __i915_gem_userptr_set_pages(obj, pvec, num_pages);

	if (obj->userptr.work == &work->work) {

		if (pinned == npages) {

			ret = __i915_gem_userptr_set_pages(obj, pvec, npages);

			if (ret == 0) {

			list_add_tail(&obj->global_list, &to_i915(dev)->mm.unbound_list);

				list_add_tail(&obj->global_list,

					      &to_i915(dev)->mm.unbound_list);

				obj->get_page.sg = obj->pages->sgl;

				obj->get_page.last = 0;



				pinned = 0;

			}

		}



		obj->userptr.work = ERR_PTR(ret);

	}



	obj->userptr.workers--;

	drm_gem_object_unreference(&obj->base);

	mutex_unlock(&dev->struct_mutex);