drm/vc4: kms: Wait on previous FIFO users before a commit

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If we're having two subsequent, non-blocking, commits on two different
CRTCs that share no resources, there's no guarantee on the order of
execution of both commits.

However, the second one will consider the first one as the old state,
and will be in charge of freeing it once that second commit is done.

If the first commit happens after that second commit, it might access
some resources related to its state that has been freed, resulting in a
use-after-free bug.

The standard DRM objects are protected against this, but our HVS private
state isn't so let's make sure we wait for all the previous FIFO users
to finish their commit before going with our own.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201204151138.1739736-5-maxime@cerno.tech

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This commit is contained in:

Maxime Ripard 2020-12-04 16:11:35 +01:00

parent d62a8ed767

commit 9ec03d7f1e

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drivers/gpu/drm/vc4/vc4_kms.c

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