From: Chris Wilson Date: Wed, 13 May 2020 18:15:57 +0000 (-0700) Subject: drm/i915/gt: Make intel_ring_unpin() safe for concurrent pint X-Git-Tag: Ubuntu-5.4.0-38.42~567 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=a5c6d35c1da9649fbc5e24944c4650daadf0375d;p=mirror_ubuntu-focal-kernel.git drm/i915/gt: Make intel_ring_unpin() safe for concurrent pint BugLink: https://bugs.launchpad.net/bugs/1877394 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 Cc: Mika Kuoppala Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20191118230254.2615942-6-chris@chris-wilson.co.uk (backported from commit a266bf42006004306dd48a9082c35dfbff153307) Signed-off-by: Sultan Alsawaf Acked-by: Stefan Bader Acked-by: Marcelo Henrique Cerri Signed-off-by: Khalid Elmously --- diff --git a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c index aeaf9986697b..daa144b890f8 100644 --- a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c @@ -1220,9 +1220,10 @@ 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: @@ -1248,20 +1249,14 @@ 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)