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From 6d55f899daa078d167aa497b71c9e7fd5f3d57fb Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 3 Dec 2019 15:50:32 +0000
Subject: [PATCH 06/11] 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 <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
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);
}
--
2.26.0
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