On 18/11/2019 23:02, Chris Wilson wrote:
In order to avoid some nasty mutex inversions, commit 09c5ab384f6f
("drm/i915: Keep rings pinned while the context is active") allowed the
intel_ring unpinning to be run concurrently with the next context
pinning it. Thus each step in intel_ring_unpin() needed to be atomic and
ordered in a nice onion with intel_ring_pin() so that the lifetimes
overlapped and were always safe.
Sadly, a few steps in intel_ring_unpin() were overlooked, such as
closing the read/write pointers of the ring and discarding the
intel_ring.vaddr, as these steps were not serialised with
intel_ring_pin() and so could leave the ring in disarray.
Fixes: 09c5ab384f6f ("drm/i915: Keep rings pinned while the context is active")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_ring.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c b/drivers/gpu/drm/i915/gt/intel_ring.c
index ece20504d240..374b28f13ca0 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring.c
@@ -57,9 +57,10 @@ int intel_ring_pin(struct intel_ring *ring)
i915_vma_make_unshrinkable(vma);
- GEM_BUG_ON(ring->vaddr);
- ring->vaddr = addr;
+ /* Discard any unused bytes beyond that submitted to hw. */
+ intel_ring_reset(ring, ring->emit);
+ ring->vaddr = addr;
return 0;
err_ring:
@@ -85,20 +86,14 @@ void intel_ring_unpin(struct intel_ring *ring)
if (!atomic_dec_and_test(&ring->pin_count))
return;
- /* Discard any unused bytes beyond that submitted to hw. */
- intel_ring_reset(ring, ring->emit);
-
i915_vma_unset_ggtt_write(vma);
if (i915_vma_is_map_and_fenceable(vma))
i915_vma_unpin_iomap(vma);
else
i915_gem_object_unpin_map(vma->obj);
- GEM_BUG_ON(!ring->vaddr);
- ring->vaddr = NULL;
-
- i915_vma_unpin(vma);
i915_vma_make_purgeable(vma);
+ i915_vma_unpin(vma);
}
static struct i915_vma *create_ring_vma(struct i915_ggtt *ggtt, int size)
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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