drm/i915: Introduce a vma.kref

Start introducing a kref on i915_vma in order to protect the vma unbind
(i915_gem_object_unbind) from a parallel destruction (i915_vma_parked).
Later, we will use the refcount to manage all access and turn i915_vma
into a first class container.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Acked-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191222210256.2066451-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index ddc82a7..46bacc8 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -194,7 +194,7 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915,
                                GEM_BUG_ON(vma->obj != obj);
                                spin_unlock(&obj->vma.lock);
 
-                               i915_vma_destroy(vma);
+                               __i915_vma_put(vma);
 
                                spin_lock(&obj->vma.lock);
                        }

diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index 497c367..2479395 100644 (file)
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -1110,8 +1110,7 @@ static int __igt_write_huge(struct intel_context *ce,
 out_vma_unpin:
        i915_vma_unpin(vma);
 out_vma_close:
-       i915_vma_destroy(vma);
-
+       __i915_vma_put(vma);
        return err;
 }
 

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index 591435c..cbf796d 100644 (file)
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -163,7 +163,7 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
        kunmap(p);
 
 out:
-       i915_vma_destroy(vma);
+       __i915_vma_put(vma);
        return err;
 }
 
@@ -257,7 +257,7 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
                if (err)
                        return err;
 
-               i915_vma_destroy(vma);
+               __i915_vma_put(vma);
 
                if (igt_timeout(end_time,
                                "%s: timed out after tiling=%d stride=%d\n",

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e9f82e9..9ddcf17 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -136,7 +136,6 @@ try_again:
                                                       struct i915_vma,
                                                       obj_link))) {
                struct i915_address_space *vm = vma->vm;
-               bool awake = false;
 
                list_move_tail(&vma->obj_link, &still_in_list);
                if (!i915_vma_is_bound(vma, I915_VMA_BIND_MASK))
@@ -147,26 +146,18 @@ try_again:
                        break;
 
                /* Prevent vma being freed by i915_vma_parked as we unbind */
-               if (intel_gt_pm_get_if_awake(vm->gt)) {
-                       awake = true;
-               } else {
-                       if (i915_vma_is_closed(vma)) {
-                               spin_unlock(&obj->vma.lock);
-                               i915_vma_parked(vm->gt);
-                               goto err_vm;
-                       }
-               }
-
+               vma = __i915_vma_get(vma);
                spin_unlock(&obj->vma.lock);
 
-               ret = -EBUSY;
-               if (flags & I915_GEM_OBJECT_UNBIND_ACTIVE ||
-                   !i915_vma_is_active(vma))
-                       ret = i915_vma_unbind(vma);
+               if (vma) {
+                       ret = -EBUSY;
+                       if (flags & I915_GEM_OBJECT_UNBIND_ACTIVE ||
+                           !i915_vma_is_active(vma))
+                               ret = i915_vma_unbind(vma);
+
+                       __i915_vma_put(vma);
+               }
 
-               if (awake)
-                       intel_gt_pm_put(vm->gt);
-err_vm:
                i915_vm_close(vm);
                spin_lock(&obj->vma.lock);
        }

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2ad2fc5..1efe58a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -534,7 +534,7 @@ void __i915_vm_close(struct i915_address_space *vm)
 
                atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
                WARN_ON(__i915_vma_unbind(vma));
-               i915_vma_destroy(vma);
+               __i915_vma_put(vma);
 
                i915_gem_object_put(obj);
        }
@@ -1812,7 +1812,7 @@ static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
 {
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
 
-       i915_vma_destroy(ppgtt->vma);
+       __i915_vma_put(ppgtt->vma);
 
        gen6_ppgtt_free_pd(ppgtt);
        free_scratch(vm);
@@ -1895,6 +1895,7 @@ static struct i915_vma *pd_vma_create(struct gen6_ppgtt *ppgtt, int size)
 
        i915_active_init(&vma->active, NULL, NULL);
 
+       kref_init(&vma->ref);
        mutex_init(&vma->pages_mutex);
        vma->vm = i915_vm_get(&ggtt->vm);
        vma->ops = &pd_vma_ops;

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index f3ac837..cbd783c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -114,6 +114,7 @@ vma_create(struct drm_i915_gem_object *obj,
        if (vma == NULL)
                return ERR_PTR(-ENOMEM);
 
+       kref_init(&vma->ref);
        mutex_init(&vma->pages_mutex);
        vma->vm = i915_vm_get(vm);
        vma->ops = &vm->vma_ops;
@@ -1021,8 +1022,10 @@ void i915_vma_reopen(struct i915_vma *vma)
                __i915_vma_remove_closed(vma);
 }
 
-void i915_vma_destroy(struct i915_vma *vma)
+void i915_vma_release(struct kref *ref)
 {
+       struct i915_vma *vma = container_of(ref, typeof(*vma), ref);
+
        if (drm_mm_node_allocated(&vma->node)) {
                mutex_lock(&vma->vm->mutex);
                atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
@@ -1072,7 +1075,7 @@ void i915_vma_parked(struct intel_gt *gt)
                spin_unlock_irq(&gt->closed_lock);
 
                if (obj) {
-                       i915_vma_destroy(vma);
+                       __i915_vma_put(vma);
                        i915_gem_object_put(obj);
                }
 
@@ -1236,7 +1239,7 @@ int __i915_vma_unbind(struct i915_vma *vma)
        i915_vma_detach(vma);
        vma_unbind_pages(vma);
 
-       drm_mm_remove_node(&vma->node); /* pairs with i915_vma_destroy() */
+       drm_mm_remove_node(&vma->node); /* pairs with i915_vma_release() */
        return 0;
 }
 

diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 0e0b61c..5fffa3c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -51,14 +51,19 @@ enum i915_cache_level;
  */
 struct i915_vma {
        struct drm_mm_node node;
-       struct drm_i915_gem_object *obj;
+
        struct i915_address_space *vm;
        const struct i915_vma_ops *ops;
-       struct i915_fence_reg *fence;
+
+       struct drm_i915_gem_object *obj;
        struct dma_resv *resv; /** Alias of obj->resv */
+
        struct sg_table *pages;
        void __iomem *iomap;
        void *private; /* owned by creator */
+
+       struct i915_fence_reg *fence;
+
        u64 size;
        u64 display_alignment;
        struct i915_page_sizes page_sizes;
@@ -74,6 +79,7 @@ struct i915_vma {
         * handles (but same file) for execbuf, i.e. the number of aliases
         * that exist in the ctx->handle_vmas LUT for this vma.
         */
+       struct kref ref;
        atomic_t open_count;
        atomic_t flags;
        /**
@@ -336,7 +342,20 @@ int __must_check i915_vma_unbind(struct i915_vma *vma);
 void i915_vma_unlink_ctx(struct i915_vma *vma);
 void i915_vma_close(struct i915_vma *vma);
 void i915_vma_reopen(struct i915_vma *vma);
-void i915_vma_destroy(struct i915_vma *vma);
+
+static inline struct i915_vma *__i915_vma_get(struct i915_vma *vma)
+{
+       if (kref_get_unless_zero(&vma->ref))
+               return vma;
+
+       return NULL;
+}
+
+void i915_vma_release(struct kref *ref);
+static inline void __i915_vma_put(struct i915_vma *vma)
+{
+       kref_put(&vma->ref, i915_vma_release);
+}
 
 #define assert_vma_held(vma) dma_resv_assert_held((vma)->resv)