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Commit 2c3a3f44 authored by Chris Wilson's avatar Chris Wilson
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drm/i915: Fix pages pin counting around swizzle quirk 



commit bc0629a7 ("drm/i915: Track pages pinned due to swizzling
quirk") fixed one problem, but revealed a whole lot more. The root cause
of the pin count mismatch for the swizzle quirk (for L-shaped memory on
gen3/4) was that we were incrementing the pages_pin_count upon getting
the backing pages but then overwriting the pages_pin_count to set it to
1 afterwards. With a little bit of adjustment to satisfy the GEM_BUG_ON
sanitychecks, the fix is to replace the explicit atomic_set with an
atomic_inc.

v2: Consistently use atomics (not mix atomics and helpers) within the
lowlevel get_pages routines. This makes the atomic operations much
clearer.

Fixes: 1233e2db ("drm/i915: Move object backing storage manipulation")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161104103001.27643-1-chris@chris-wilson.co.uk


Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent a44342ac

drivers/gpu/drm/i915/i915_gem.c

+26 −21
Original line number Diff line number Diff line
@@ -2324,12 +2324,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) 
	if (i915_gem_object_needs_bit17_swizzle(obj))

		i915_gem_object_do_bit_17_swizzle(obj, st);



	if (i915_gem_object_is_tiled(obj) &&

	    dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {

		__i915_gem_object_pin_pages(obj);

		obj->mm.quirked = true;

	}



	return st;



err_pages:
@@ -2362,12 +2356,21 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj, 
	obj->mm.get_page.sg_idx = 0;



	obj->mm.pages = pages;



	if (i915_gem_object_is_tiled(obj) &&

	    to_i915(obj->base.dev)->quirks & QUIRK_PIN_SWIZZLED_PAGES) {

		GEM_BUG_ON(obj->mm.quirked);

		__i915_gem_object_pin_pages(obj);

		obj->mm.quirked = true;

	}

}



static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)

{

	struct sg_table *pages;



	GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));



	if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {

		DRM_DEBUG("Attempting to obtain a purgeable object\n");

		return -EFAULT;
@@ -2396,16 +2399,14 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj) 
	if (err)

		return err;



	if (likely(obj->mm.pages)) {

		__i915_gem_object_pin_pages(obj);

	if (unlikely(!obj->mm.pages)) {

		err = ____i915_gem_object_get_pages(obj);

		if (err)

			goto unlock;

	}



	GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));



	err = ____i915_gem_object_get_pages(obj);

	if (!err)

		atomic_set_release(&obj->mm.pages_pin_count, 1);

		smp_mb__before_atomic();

	}

	atomic_inc(&obj->mm.pages_pin_count);



unlock:

	mutex_unlock(&obj->mm.lock);
@@ -2476,12 +2477,14 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, 


	pinned = true;

	if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {

		if (unlikely(!obj->mm.pages)) {

			ret = ____i915_gem_object_get_pages(obj);

			if (ret)

				goto err_unlock;



		GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count));

		atomic_set_release(&obj->mm.pages_pin_count, 1);

			smp_mb__before_atomic();

		}

		atomic_inc(&obj->mm.pages_pin_count);

		pinned = false;

	}

	GEM_BUG_ON(!obj->mm.pages);
@@ -2933,7 +2936,7 @@ int i915_vma_unbind(struct i915_vma *vma) 
		goto destroy;



	GEM_BUG_ON(obj->bind_count == 0);

	GEM_BUG_ON(!obj->mm.pages);

	GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));



	if (i915_vma_is_map_and_fenceable(vma)) {

		/* release the fence reg _after_ flushing */
@@ -3167,6 +3170,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags) 
	list_move_tail(&obj->global_link, &dev_priv->mm.bound_list);

	list_move_tail(&vma->vm_link, &vma->vm->inactive_list);

	obj->bind_count++;

	GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);



	return 0;
@@ -4100,6 +4104,7 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data, 
			obj->mm.quirked = false;

		}

		if (args->madv == I915_MADV_WILLNEED) {

			GEM_BUG_ON(obj->mm.quirked);

			__i915_gem_object_pin_pages(obj);

			obj->mm.quirked = true;

		}

drivers/gpu/drm/i915/i915_gem_gtt.c

+7 −0
Original line number Diff line number Diff line
@@ -3711,6 +3711,13 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma) 
{

	int ret = 0;



	/* The vma->pages are only valid within the lifespan of the borrowed

	 * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so

	 * must be the vma->pages. A simple rule is that vma->pages must only

	 * be accessed when the obj->mm.pages are pinned.

	 */

	GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));



	if (vma->pages)

		return 0;

drivers/gpu/drm/i915/i915_gem_tiling.c

+1 −0
Original line number Diff line number Diff line
@@ -269,6 +269,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data, 
					obj->mm.quirked = false;

				}

				if (!i915_gem_object_is_tiled(obj)) {

					GEM_BUG_ON(!obj->mm.quirked);

					__i915_gem_object_pin_pages(obj);

					obj->mm.quirked = true;

				}