From 4e14c86bb1575e16cfa0da8e7b670497b8c95657 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 3 Dec 2019 15:50:32 +0000 Subject: [PATCH 06/12] drm/i915/gem: Avoid parking the vma as we unbind In order to avoid keeping a reference on the i915_vma (which is long overdue!) we have to coordinate all the possible lifetimes and only use the vma while we know it is alive. In this episode, we are reminded that while idle, the closed vma are destroyed. So if the GT idles while we are working with the vma, the vma itself becomes invalid. First class i915_vma here we come, but in the meantime keep piling on the straw. Signed-off-by: Chris Wilson Reviewed-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20191203155032.3137263-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index ed2436db5dd2..739543812422 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -141,18 +141,33 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj, struct i915_vma, obj_link))) { struct i915_address_space *vm = vma->vm; + bool awake = false; - ret = -EBUSY; + ret = -EAGAIN; if (!i915_vm_tryopen(vm)) 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); + goto err_vm; + } + } + list_move_tail(&vma->obj_link, &still_in_list); 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 (awake) + intel_gt_pm_put(vm->gt); +err_vm: i915_vm_close(vm); spin_lock(&obj->vma.lock); } -- 2.25.2