linux-stable.git/include/linux/dma-resv.h, branch v5.4.239 Linux kernel stable tree dma-buf: Restore seqlock around dma_resv updates 2019-08-16T11:40:58+00:00 Chris Wilson chris@chris-wilson.co.uk 2019-08-14T18:24:01+00:00 b016cd6ed4b772759804e0d6082bd1f5ca63b8ee This reverts 67c97fb79a7f ("dma-buf: add reservation_object_fences helper") dd7a7d1ff2f1 ("drm/i915: use new reservation_object_fences helper") 0e1d8083bddb ("dma-buf: further relax reservation_object_add_shared_fence") 5d344f58da76 ("dma-buf: nuke reservation_object seq number") The scenario that defeats simply grabbing a set of shared/exclusive fences and using them blissfully under RCU is that any of those fences may be reallocated by a SLAB_TYPESAFE_BY_RCU fence slab cache. In this scenario, while keeping the rcu_read_lock we need to establish that no fence was changed in the dma_resv after a read (or full) memory barrier. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190814182401.25009-1-chris@chris-wilson.co.uk 
This reverts
67c97fb79a7f ("dma-buf: add reservation_object_fences helper")
dd7a7d1ff2f1 ("drm/i915: use new reservation_object_fences helper")
0e1d8083bddb ("dma-buf: further relax reservation_object_add_shared_fence")
5d344f58da76 ("dma-buf: nuke reservation_object seq number")

The scenario that defeats simply grabbing a set of shared/exclusive
fences and using them blissfully under RCU is that any of those fences
may be reallocated by a SLAB_TYPESAFE_BY_RCU fence slab cache. In this
scenario, while keeping the rcu_read_lock we need to establish that no
fence was changed in the dma_resv after a read (or full) memory barrier.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190814182401.25009-1-chris@chris-wilson.co.uk
dma-buf: rename reservation_object to dma_resv 2019-08-13T07:09:30+00:00 Christian König christian.koenig@amd.com 2019-08-11T08:06:32+00:00 52791eeec1d9f4a7e7fe08aaba0b1553149d93bc Be more consistent with the naming of the other DMA-buf objects. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/323401/ 
Be more consistent with the naming of the other DMA-buf objects.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/323401/