Commit 60e94557 authored Jan 23, 2020 by Chris Wilson

drm/i915: Check activity on i915_vma after confirming pin_count==0

Only assert that the i915_vma is now idle if and only if no other pins
are present. If another user has the i915_vma pinned, they may submit
more work to the i915_vma skipping the vm->mutex used to serialise the
unbind. We need to wait again, if we want to continue and unbind this
vma.

However, if we own the i915_vma (we hold the vm->mutex for the unbind
and the pin_count is 0), we can assert that the vma remains idle as we
unbind.

Fixes: 2850748e ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Closes: https://gitlab.freedesktop.org/drm/intel/issues/530


Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123224459.38128-1-chris@chris-wilson.co.uk

parent 90211ea4

drivers/gpu/drm/i915/i915_vma.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -1202,16 +1202,26 @@ int __i915_vma_unbind(struct i915_vma *vma)
		if (ret)
		return ret;

		GEM_BUG_ON(i915_vma_is_active(vma));
		if (i915_vma_is_pinned(vma)) {
		vma_print_allocator(vma, "is pinned");
		return -EAGAIN;
		}

		GEM_BUG_ON(i915_vma_is_active(vma));
		/*
		* After confirming that no one else is pinning this vma, wait for
		* any laggards who may have crept in during the wait (through
		* a residual pin skipping the vm->mutex) to complete.
		*/
		ret = i915_vma_sync(vma);
		if (ret)
		return ret;

		if (!drm_mm_node_allocated(&vma->node))
		return 0;

		GEM_BUG_ON(i915_vma_is_pinned(vma));
		GEM_BUG_ON(i915_vma_is_active(vma));

		if (i915_vma_is_map_and_fenceable(vma)) {
		/*
		* Check that we have flushed all writes through the GGTT

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