drm/i915: Also drop vm.ref along error paths for vma construction

Not only do we need to release the vm.ref we acquired for the vma on the
duplicate insert branch, but also for the normal error paths, so roll
them all into one.

Reported-by: Andi Shyti <andi.shyti@intel.com>
Suggested-by: Andi Shyti <andi.shyti@intel.com>
Fixes: 2850748ef876 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: <stable@vger.kernel.org> # v5.5+
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200702211015.29604-1-chris@chris-wilson.co.uk
(cherry picked from commit 03fca66b7a36b52da8915341eee388267f6d5b73)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 2d60fd1f36372832830861e5acf5e2c0abcddea0..1f9cd33b35cb33afa3cd90d02f8b433398af8f52 100644 (file)
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -104,6 +104,7 @@ vma_create(struct drm_i915_gem_object *obj,
           struct i915_address_space *vm,
           const struct i915_ggtt_view *view)
 {
+       struct i915_vma *pos = ERR_PTR(-E2BIG);
        struct i915_vma *vma;
        struct rb_node *rb, **p;
 
@@ -184,7 +185,6 @@ vma_create(struct drm_i915_gem_object *obj,
        rb = NULL;
        p = &obj->vma.tree.rb_node;
        while (*p) {
-               struct i915_vma *pos;
                long cmp;
 
                rb = *p;
@@ -196,17 +196,12 @@ vma_create(struct drm_i915_gem_object *obj,
                 * and dispose of ours.
                 */
                cmp = i915_vma_compare(pos, vm, view);
-               if (cmp == 0) {
-                       spin_unlock(&obj->vma.lock);
-                       i915_vm_put(vm);
-                       i915_vma_free(vma);
-                       return pos;
-               }
-
                if (cmp < 0)
                        p = &rb->rb_right;
-               else
+               else if (cmp > 0)
                        p = &rb->rb_left;
+               else
+                       goto err_unlock;
        }
        rb_link_node(&vma->obj_node, rb, p);
        rb_insert_color(&vma->obj_node, &obj->vma.tree);
@@ -229,8 +224,9 @@ vma_create(struct drm_i915_gem_object *obj,
 err_unlock:
        spin_unlock(&obj->vma.lock);
 err_vma:
+       i915_vm_put(vm);
        i915_vma_free(vma);
-       return ERR_PTR(-E2BIG);
+       return pos;
 }
 
 static struct i915_vma *