drm/i915/gt: Make intel_ring_unpin() safe for concurrent pint

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In order to avoid some nasty mutex inversions, commit 09c5ab384f
("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: 09c5ab384f ("drm/i915: Keep rings pinned while the context is active")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118230254.2615942-6-chris@chris-wilson.co.uk
(cherry picked from commit a266bf4200)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

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Chris Wilson 2019-11-18 23:02:40 +00:00 • committed by Joonas Lahtinen

parent 311770173f

commit 0725d9a318

1 changed files with 4 additions and 9 deletions

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drivers/gpu/drm/i915/gt/intel_ring.c

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