dma-buf/sw_sync: Avoid recursive lock during fence signal

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[ Upstream commit e531fdb5cd ]

If a signal callback releases the sw_sync fence, that will trigger a
deadlock as the timeline_fence_release recurses onto the fence->lock
(used both for signaling and the the timeline tree).

To avoid that, temporarily hold an extra reference to the signalled
fences until after we drop the lock.

(This is an alternative implementation of https://patchwork.kernel.org/patch/11664717/
which avoids some potential UAF issues with the original patch.)

v2: Remove now obsolete comment, use list_move_tail() and
    list_del_init()

Reported-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Fixes: d3c6dd1fb3 ("dma-buf/sw_sync: Synchronize signal vs syncpt free")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230818145939.39697-1-robdclark@gmail.com
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Rob Clark 2023-08-18 07:59:38 -07:00 • committed by Greg Kroah-Hartman

parent 8c776cd8f1

commit c6e1fcd50c

1 changed files with 9 additions and 9 deletions

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drivers/dma-buf/sw_sync.c

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