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linux-next/drivers/dma-buf
Michel Dänzer 7f43ef9f0d dma-buf: Move BUG_ON from _add_shared_fence to _add_shared_inplace
Fixes the BUG_ON spuriously triggering under the following
circumstances:

* reservation_object_reserve_shared is called with shared_count ==
  shared_max - 1, so obj->staged is freed in preparation of an in-place
  update.

* reservation_object_add_shared_fence is called with the first fence,
  after which shared_count == shared_max.

* reservation_object_add_shared_fence is called with a follow-up fence
  from the same context.

In the second reservation_object_add_shared_fence call, the BUG_ON
triggers. However, nothing bad would happen in
reservation_object_add_shared_inplace, since both fences are from the
same context, so they only occupy a single slot.

Prevent this by moving the BUG_ON to where an overflow would actually
happen (e.g. if a buggy caller didn't call
reservation_object_reserve_shared before).

v2:
* Fix description of breaking scenario (Christian König)
* Add bugzilla reference

Cc: stable@vger.kernel.org
Bugzilla: https://bugs.freedesktop.org/106418
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Reviewed-by: Christian König <christian.koenig@amd.com> # v1
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704151405.10357-1-michel@daenzer.net
2018-07-16 20:20:37 +05:30
..
dma-buf.c dma-buf: remove kmap_atomic interface 2018-06-20 15:59:34 +02:00
dma-fence-array.c dma-fence: Make ->wait callback optional 2018-07-03 13:12:57 +02:00
dma-fence.c dma-fence: Polish kernel-doc for dma-fence.c 2018-07-04 12:18:37 +02:00
Kconfig dma-buf: Rename struct fence to dma_fence 2016-10-25 14:40:39 +02:00
Makefile dma-buf: Rename struct fence to dma_fence 2016-10-25 14:40:39 +02:00
reservation.c dma-buf: Move BUG_ON from _add_shared_fence to _add_shared_inplace 2018-07-16 20:20:37 +05:30
seqno-fence.c dma-buf: Rename struct fence to dma_fence 2016-10-25 14:40:39 +02:00
sw_sync.c dma-fence: Make ->wait callback optional 2018-07-03 13:12:57 +02:00
sync_debug.c Linux 4.13-rc2 2017-07-27 08:15:43 +10:00
sync_debug.h dma-buf: Remove unneeded stubs around sync_debug interfaces 2018-05-07 15:58:07 +02:00
sync_file.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
sync_trace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00