If we cannot handle a vma within the unbind loop, try to flush the
pending events (i915_vma_parked, i915_vm_release) and try again. This
avoids a round trip to userspace that is not guaranteed to make forward
progress, as the events we wait upon require being idle.
References: cb6c3d45f948 ("drm/i915/gem: Avoid parking the vma as we unbind")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index eb9e2609c569..377487a0762e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -123,7 +123,7 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
LIST_HEAD(still_in_list);
intel_wakeref_t wakeref;
struct i915_vma *vma;
- int ret = 0;
+ int ret;
if (!atomic_read(&obj->bind_count))
return 0;
@@ -136,6 +136,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
*/
wakeref = intel_runtime_pm_get(rpm);
+try_again:
+ ret = 0;
spin_lock(&obj->vma.lock);
while (!ret && (vma = list_first_entry_or_null(&obj->vma.list,
struct i915_vma,
@@ -153,6 +155,7 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
} else {
if (i915_vma_is_closed(vma)) {
spin_unlock(&obj->vma.lock);
+ i915_vma_parked(vm->gt);
goto err_vm;
}
}
@@ -174,6 +177,11 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
list_splice(&still_in_list, &obj->vma.list);
spin_unlock(&obj->vma.lock);
+ if (ret == -EAGAIN && flags & I915_GEM_OBJECT_UNBIND_ACTIVE) {
+ rcu_barrier(); /* flush the i915_vm_release() */
+ goto try_again;
+ }
+
intel_runtime_pm_put(rpm, wakeref);
return ret;
--
2.24.0
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