[Intel-gfx] [CI 3/5] drm/i915: Move vma lookup to its own lock
Chris Wilson
chris at chris-wilson.co.uk
Mon Jan 28 10:23:54 UTC 2019
Remove the struct_mutex requirement for looking up the vma for an
object.
v2: Highlight how the race for duplicate vma creation is resolved on
reacquiring the lock with a short comment.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
drivers/gpu/drm/i915/i915_debugfs.c | 6 +--
drivers/gpu/drm/i915/i915_gem.c | 33 +++++++-----
drivers/gpu/drm/i915/i915_gem_object.h | 45 +++++++++-------
drivers/gpu/drm/i915/i915_vma.c | 66 ++++++++++++++++-------
drivers/gpu/drm/i915/i915_vma.h | 2 +-
drivers/gpu/drm/i915/selftests/i915_vma.c | 4 +-
6 files changed, 98 insertions(+), 58 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index e46de507fea2..f5ac03f06e26 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -160,14 +160,14 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
obj->mm.madv == I915_MADV_DONTNEED ? " purgeable" : "");
if (obj->base.name)
seq_printf(m, " (name: %d)", obj->base.name);
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ list_for_each_entry(vma, &obj->vma.list, obj_link) {
if (i915_vma_is_pinned(vma))
pin_count++;
}
seq_printf(m, " (pinned x %d)", pin_count);
if (obj->pin_global)
seq_printf(m, " (global)");
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ list_for_each_entry(vma, &obj->vma.list, obj_link) {
if (!drm_mm_node_allocated(&vma->node))
continue;
@@ -323,7 +323,7 @@ static int per_file_stats(int id, void *ptr, void *data)
if (obj->base.name || obj->base.dma_buf)
stats->shared += obj->base.size;
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ list_for_each_entry(vma, &obj->vma.list, obj_link) {
if (!drm_mm_node_allocated(&vma->node))
continue;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 111a047a45b7..653c7ba4c69f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -439,15 +439,19 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj)
if (ret)
return ret;
- while ((vma = list_first_entry_or_null(&obj->vma_list,
- struct i915_vma,
- obj_link))) {
+ spin_lock(&obj->vma.lock);
+ while (!ret && (vma = list_first_entry_or_null(&obj->vma.list,
+ struct i915_vma,
+ obj_link))) {
list_move_tail(&vma->obj_link, &still_in_list);
+ spin_unlock(&obj->vma.lock);
+
ret = i915_vma_unbind(vma);
- if (ret)
- break;
+
+ spin_lock(&obj->vma.lock);
}
- list_splice(&still_in_list, &obj->vma_list);
+ list_splice(&still_in_list, &obj->vma.list);
+ spin_unlock(&obj->vma.lock);
return ret;
}
@@ -3491,7 +3495,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
* reading an invalid PTE on older architectures.
*/
restart:
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ list_for_each_entry(vma, &obj->vma.list, obj_link) {
if (!drm_mm_node_allocated(&vma->node))
continue;
@@ -3569,7 +3573,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
*/
}
- list_for_each_entry(vma, &obj->vma_list, obj_link) {
+ list_for_each_entry(vma, &obj->vma.list, obj_link) {
if (!drm_mm_node_allocated(&vma->node))
continue;
@@ -3579,7 +3583,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
}
}
- list_for_each_entry(vma, &obj->vma_list, obj_link)
+ list_for_each_entry(vma, &obj->vma.list, obj_link)
vma->node.color = cache_level;
i915_gem_object_set_cache_coherency(obj, cache_level);
obj->cache_dirty = true; /* Always invalidate stale cachelines */
@@ -4155,7 +4159,9 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
{
mutex_init(&obj->mm.lock);
- INIT_LIST_HEAD(&obj->vma_list);
+ spin_lock_init(&obj->vma.lock);
+ INIT_LIST_HEAD(&obj->vma.list);
+
INIT_LIST_HEAD(&obj->lut_list);
INIT_LIST_HEAD(&obj->batch_pool_link);
@@ -4321,14 +4327,13 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915,
mutex_lock(&i915->drm.struct_mutex);
GEM_BUG_ON(i915_gem_object_is_active(obj));
- list_for_each_entry_safe(vma, vn,
- &obj->vma_list, obj_link) {
+ list_for_each_entry_safe(vma, vn, &obj->vma.list, obj_link) {
GEM_BUG_ON(i915_vma_is_active(vma));
vma->flags &= ~I915_VMA_PIN_MASK;
i915_vma_destroy(vma);
}
- GEM_BUG_ON(!list_empty(&obj->vma_list));
- GEM_BUG_ON(!RB_EMPTY_ROOT(&obj->vma_tree));
+ GEM_BUG_ON(!list_empty(&obj->vma.list));
+ GEM_BUG_ON(!RB_EMPTY_ROOT(&obj->vma.tree));
/* This serializes freeing with the shrinker. Since the free
* is delayed, first by RCU then by the workqueue, we want the
diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index cb1b0144d274..73fec917d097 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -87,24 +87,33 @@ struct drm_i915_gem_object {
const struct drm_i915_gem_object_ops *ops;
- /**
- * @vma_list: List of VMAs backed by this object
- *
- * The VMA on this list are ordered by type, all GGTT vma are placed
- * at the head and all ppGTT vma are placed at the tail. The different
- * types of GGTT vma are unordered between themselves, use the
- * @vma_tree (which has a defined order between all VMA) to find an
- * exact match.
- */
- struct list_head vma_list;
- /**
- * @vma_tree: Ordered tree of VMAs backed by this object
- *
- * All VMA created for this object are placed in the @vma_tree for
- * fast retrieval via a binary search in i915_vma_instance().
- * They are also added to @vma_list for easy iteration.
- */
- struct rb_root vma_tree;
+ struct {
+ /**
+ * @vma.lock: protect the list/tree of vmas
+ */
+ spinlock_t lock;
+
+ /**
+ * @vma.list: List of VMAs backed by this object
+ *
+ * The VMA on this list are ordered by type, all GGTT vma are
+ * placed at the head and all ppGTT vma are placed at the tail.
+ * The different types of GGTT vma are unordered between
+ * themselves, use the @vma.tree (which has a defined order
+ * between all VMA) to quickly find an exact match.
+ */
+ struct list_head list;
+
+ /**
+ * @vma.tree: Ordered tree of VMAs backed by this object
+ *
+ * All VMA created for this object are placed in the @vma.tree
+ * for fast retrieval via a binary search in
+ * i915_vma_instance(). They are also added to @vma.list for
+ * easy iteration.
+ */
+ struct rb_root tree;
+ } vma;
/**
* @lut_list: List of vma lookup entries in use for this object.
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index dcbd0d345c72..d83b8ad5f859 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -187,32 +187,52 @@ vma_create(struct drm_i915_gem_object *obj,
i915_gem_object_get_stride(obj));
GEM_BUG_ON(!is_power_of_2(vma->fence_alignment));
- /*
- * We put the GGTT vma at the start of the vma-list, followed
- * by the ppGGTT vma. This allows us to break early when
- * iterating over only the GGTT vma for an object, see
- * for_each_ggtt_vma()
- */
vma->flags |= I915_VMA_GGTT;
- list_add(&vma->obj_link, &obj->vma_list);
- } else {
- list_add_tail(&vma->obj_link, &obj->vma_list);
}
+ spin_lock(&obj->vma.lock);
+
rb = NULL;
- p = &obj->vma_tree.rb_node;
+ p = &obj->vma.tree.rb_node;
while (*p) {
struct i915_vma *pos;
+ long cmp;
rb = *p;
pos = rb_entry(rb, struct i915_vma, obj_node);
- if (i915_vma_compare(pos, vm, view) < 0)
+
+ /*
+ * If the view already exists in the tree, another thread
+ * already created a matching vma, so return the older instance
+ * and dispose of ours.
+ */
+ cmp = i915_vma_compare(pos, vm, view);
+ if (cmp == 0) {
+ spin_unlock(&obj->vma.lock);
+ kmem_cache_free(vm->i915->vmas, vma);
+ return pos;
+ }
+
+ if (cmp < 0)
p = &rb->rb_right;
else
p = &rb->rb_left;
}
rb_link_node(&vma->obj_node, rb, p);
- rb_insert_color(&vma->obj_node, &obj->vma_tree);
+ rb_insert_color(&vma->obj_node, &obj->vma.tree);
+
+ if (i915_vma_is_ggtt(vma))
+ /*
+ * We put the GGTT vma at the start of the vma-list, followed
+ * by the ppGGTT vma. This allows us to break early when
+ * iterating over only the GGTT vma for an object, see
+ * for_each_ggtt_vma()
+ */
+ list_add(&vma->obj_link, &obj->vma.list);
+ else
+ list_add_tail(&vma->obj_link, &obj->vma.list);
+
+ spin_unlock(&obj->vma.lock);
mutex_lock(&vm->mutex);
list_add(&vma->vm_link, &vm->unbound_list);
@@ -232,7 +252,7 @@ vma_lookup(struct drm_i915_gem_object *obj,
{
struct rb_node *rb;
- rb = obj->vma_tree.rb_node;
+ rb = obj->vma.tree.rb_node;
while (rb) {
struct i915_vma *vma = rb_entry(rb, struct i915_vma, obj_node);
long cmp;
@@ -272,16 +292,18 @@ i915_vma_instance(struct drm_i915_gem_object *obj,
{
struct i915_vma *vma;
- lockdep_assert_held(&obj->base.dev->struct_mutex);
GEM_BUG_ON(view && !i915_is_ggtt(vm));
GEM_BUG_ON(vm->closed);
+ spin_lock(&obj->vma.lock);
vma = vma_lookup(obj, vm, view);
- if (!vma)
+ spin_unlock(&obj->vma.lock);
+
+ /* vma_create() will resolve the race if another creates the vma */
+ if (unlikely(!vma))
vma = vma_create(obj, vm, view);
GEM_BUG_ON(!IS_ERR(vma) && i915_vma_compare(vma, vm, view));
- GEM_BUG_ON(!IS_ERR(vma) && vma_lookup(obj, vm, view) != vma);
return vma;
}
@@ -808,14 +830,18 @@ static void __i915_vma_destroy(struct i915_vma *vma)
GEM_BUG_ON(i915_gem_active_isset(&vma->last_fence));
- list_del(&vma->obj_link);
-
mutex_lock(&vma->vm->mutex);
list_del(&vma->vm_link);
mutex_unlock(&vma->vm->mutex);
- if (vma->obj)
- rb_erase(&vma->obj_node, &vma->obj->vma_tree);
+ if (vma->obj) {
+ struct drm_i915_gem_object *obj = vma->obj;
+
+ spin_lock(&obj->vma.lock);
+ list_del(&vma->obj_link);
+ rb_erase(&vma->obj_node, &vma->obj->vma.tree);
+ spin_unlock(&obj->vma.lock);
+ }
rbtree_postorder_for_each_entry_safe(iter, n, &vma->active, node) {
GEM_BUG_ON(i915_gem_active_isset(&iter->base));
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 4f7c1c7599f4..7252abc73d3e 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -425,7 +425,7 @@ void i915_vma_parked(struct drm_i915_private *i915);
* or the list is empty ofc.
*/
#define for_each_ggtt_vma(V, OBJ) \
- list_for_each_entry(V, &(OBJ)->vma_list, obj_link) \
+ list_for_each_entry(V, &(OBJ)->vma.list, obj_link) \
for_each_until(!i915_vma_is_ggtt(V))
#endif
diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
index f0a32edfb9b1..cf1de82741fa 100644
--- a/drivers/gpu/drm/i915/selftests/i915_vma.c
+++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
@@ -672,7 +672,7 @@ static int igt_vma_partial(void *arg)
}
count = 0;
- list_for_each_entry(vma, &obj->vma_list, obj_link)
+ list_for_each_entry(vma, &obj->vma.list, obj_link)
count++;
if (count != nvma) {
pr_err("(%s) All partial vma were not recorded on the obj->vma_list: found %u, expected %u\n",
@@ -701,7 +701,7 @@ static int igt_vma_partial(void *arg)
i915_vma_unpin(vma);
count = 0;
- list_for_each_entry(vma, &obj->vma_list, obj_link)
+ list_for_each_entry(vma, &obj->vma.list, obj_link)
count++;
if (count != nvma) {
pr_err("(%s) allocated an extra full vma!\n", p->name);
--
2.20.1
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