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alistair23-linux/drivers/gpu
Chris Wilson 02978ff57a drm/i915: Fix write-read race with multiple rings
Daniel noticed a problem where is we wrote to an object with ring A in
the middle of a very long running batch, then executed a quick batch on
ring B before a batch that reads from the same object, its obj->ring would
now point to ring B, but its last_write_seqno would be still relative to
ring A. This would allow for the user to read from the object before the
GPU had completed the write, as set_domain would only check that ring B
had passed the last_write_seqno.

To fix this simply (and inelegantly), we bump the last_write_seqno when
switching rings so that the last_write_seqno is always relative to the
current obj->ring.

This fixes igt/tests/gem_write_read_ring_switch.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
[danvet: Add note about the newly created igt which exercises this
bug.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2013-07-10 10:41:55 +02:00
..
drm drm/i915: Fix write-read race with multiple rings 2013-07-10 10:41:55 +02:00
host1x gpu: host1x: Rework CPU syncpoint increment 2013-06-22 12:43:55 +02:00
vga fbcon: fix locking harder 2013-02-08 12:02:43 +10:00
Makefile gpu: host1x: Add host1x driver 2013-04-22 12:32:40 +02:00