[PATCH 34/55] drm/i915: Count how many VMA are bound for an object

Chris Wilson
2016-07-25T17:39:17Z

Since we may have VMA allocated for an object, but we interrupted their
binding, there is a disparity between have elements on the obj->vma_list
and being bound. i915_gem_obj_bound_any() does this check, but this is
not rigorously observed - add an explicit count to make it easier.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_debugfs.c | 12 +++++------
drivers/gpu/drm/i915/i915_drv.h | 3 ++-
drivers/gpu/drm/i915/i915_gem.c | 34 +++++++++++++-------------------
drivers/gpu/drm/i915/i915_gem_shrinker.c | 17 +---------------
drivers/gpu/drm/i915/i915_gem_stolen.c | 1 +
5 files changed, 23 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 2fc81865e657..b638ecea0c03 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -174,6 +174,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
if (obj->fence_reg != I915_FENCE_REG_NONE)
seq_printf(m, " (fence: %d)", obj->fence_reg);
list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ if (!drm_mm_node_allocated(&vma->node))
+ continue;
+
seq_printf(m, " (%sgtt offset: %08llx, size: %08llx",
vma->is_ggtt ? "g" : "pp",
vma->node.start, vma->node.size);
@@ -335,11 +338,11 @@ static int per_file_stats(int id, void *ptr, void *data)
struct drm_i915_gem_object *obj = ptr;
struct file_stats *stats = data;
struct i915_vma *vma;
- int bound = 0;

stats->count++;
stats->total += obj->base.size;
-
+ if (!obj->bind_count)
+ stats->unbound += obj->base.size;
if (obj->base.name || obj->base.dma_buf)
stats->shared += obj->base.size;

@@ -347,8 +350,6 @@ static int per_file_stats(int id, void *ptr, void *data)
if (!drm_mm_node_allocated(&vma->node))
continue;

- bound++;
-
if (vma->is_ggtt) {
stats->global += vma->node.size;
} else {
@@ -366,9 +367,6 @@ static int per_file_stats(int id, void *ptr, void *data)
stats->inactive += vma->node.size;
}

- if (!bound)
- stats->unbound += obj->base.size;
-
return 0;
}

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 4c38307d2554..e28228c6f383 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2221,6 +2221,8 @@ struct drm_i915_gem_object {
unsigned int frontbuffer_bits:INTEL_FRONTBUFFER_BITS;

unsigned int has_wc_mmap;
+ /** Count of VMA actually bound by this object */
+ unsigned int bind_count;
unsigned int pin_display;

struct sg_table *pages;
@@ -3266,7 +3268,6 @@ i915_gem_obj_ggtt_offset(struct drm_i915_gem_object *o)
return i915_gem_obj_ggtt_offset_view(o, &i915_ggtt_view_normal);
}

-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o);
bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
const struct i915_ggtt_view *view);
bool i915_gem_obj_bound(struct drm_i915_gem_object *o,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a0ea1ee16f67..a3defd7b4046 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2107,7 +2107,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
if (obj->pages_pin_count)
return -EBUSY;

- BUG_ON(i915_gem_obj_bound_any(obj));
+ GEM_BUG_ON(obj->bind_count);

/* ->put_pages might need to allocate memory for the bit17 swizzle
* array, hence protect them from being reaped by removing them from gtt
@@ -2965,7 +2965,6 @@ static void __i915_vma_iounmap(struct i915_vma *vma)
static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
{
struct drm_i915_gem_object *obj = vma->obj;
- struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
int ret;

if (list_empty(&vma->obj_link))
@@ -2979,7 +2978,8 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
if (vma->pin_count)
return -EBUSY;

- BUG_ON(obj->pages == NULL);
+ GEM_BUG_ON(obj->bind_count == 0);
+ GEM_BUG_ON(!obj->pages);

if (wait) {
ret = i915_gem_object_wait_rendering(obj, false);
@@ -3019,8 +3019,9 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)

/* Since the unbound list is global, only move to that list if
* no more VMAs exist. */
- if (list_empty(&obj->vma_list))
- list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);
+ if (--obj->bind_count == 0)
+ list_move_tail(&obj->global_list,
+ &to_i915(obj->base.dev)->mm.unbound_list);

/* And finally now the object is completely decoupled from this vma,
* we can drop its hold on the backing storage and allow it to be
@@ -3255,6 +3256,7 @@ search_free:

list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
list_add_tail(&vma->vm_link, &vm->inactive_list);
+ obj->bind_count++;

return vma;

@@ -3450,7 +3452,6 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
{
struct drm_device *dev = obj->base.dev;
struct i915_vma *vma, *next;
- bool bound = false;
int ret = 0;

if (obj->cache_level == cache_level)
@@ -3474,8 +3475,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
ret = i915_vma_unbind(vma);
if (ret)
return ret;
- } else
- bound = true;
+ }
}

/* We can reuse the existing drm_mm nodes but need to change the
@@ -3485,7 +3485,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
* rewrite the PTE in the belief that doing so tramples upon less
* state and so involves less work.
*/
- if (bound) {
+ if (obj->bind_count) {
/* Before we change the PTE, the GPU must not be accessing it.
* If we wait upon the object, we know that all the bound
* VMA are no longer active.
@@ -3692,6 +3692,9 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
old_read_domains,
old_write_domain);

+ /* Increment the pages_pin_count to guard against the shrinker */
+ obj->pages_pin_count++;
+
return 0;

err_unpin_display:
@@ -3708,6 +3711,7 @@ i915_gem_object_unpin_from_display_plane(struct drm_i915_gem_object *obj,

i915_gem_object_ggtt_unpin_view(obj, view);

+ obj->pages_pin_count--;
obj->pin_display--;
}

@@ -4223,6 +4227,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
dev_priv->mm.interruptible = was_interruptible;
}
}
+ GEM_BUG_ON(obj->bind_count);

/* Stolen objects don't hold a ref, but do hold pin count. Fix that up
* before progressing. */
@@ -4840,17 +4845,6 @@ bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
return false;
}

-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o)
-{
- struct i915_vma *vma;
-
- list_for_each_entry(vma, &o->vma_list, obj_link)
- if (drm_mm_node_allocated(&vma->node))
- return true;
-
- return false;
-}
-
unsigned long i915_gem_obj_ggtt_size(struct drm_i915_gem_object *o)
{
struct i915_vma *vma;
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 5d4772c146b1..1b700afd6134 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -48,21 +48,6 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
#endif
}

-static int num_vma_bound(struct drm_i915_gem_object *obj)
-{
- struct i915_vma *vma;
- int count = 0;
-
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
- if (drm_mm_node_allocated(&vma->node))
- count++;
- if (vma->pin_count)
- count++;
- }
-
- return count;
-}
-
static bool swap_available(void)
{
return get_nr_swap_pages() > 0;
@@ -82,7 +67,7 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
* to the GPU, simply unbinding from the GPU is not going to succeed
* in releasing our pin count on the pages themselves.
*/
- if (obj->pages_pin_count != num_vma_bound(obj))
+ if (obj->pages_pin_count > obj->bind_count)
return false;

/* We can only return physical pages to the system if we can either
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 9a8cc8c51077..2c321c8df7c3 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -708,6 +708,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
vma->bound |= GLOBAL_BIND;
__i915_vma_set_map_and_fenceable(vma);
list_add_tail(&vma->vm_link, &ggtt->base.inactive_list);
+ obj->bind_count++;

list_add_tail(&obj->global_list, &dev_priv->mm.bound_list);
i915_gem_object_pin_pages(obj);
--
2.8.1