drm/amdgpu: Fix vmid_wait fence leak in amdgpu_ring_init()

amdgpu_ring_init() initializes ring->vmid_wait with a reference to the
stub fence taken via dma_fence_get_stub().  When a later step of the
initialization fails, e.g. amdgpu_fence_driver_init_ring(), a writeback
slot allocation or the ring buffer allocation, the function returns an
error without releasing the stub fence reference and the reference is
leaked if the ring is torn down without amdgpu_ring_fini().

Move the stub fence assignment to the end of the initialization, right
before the ring is registered with the GPU scheduler, where no further
failure is possible.  The stub fence is only consumed by command
submission handling in amdgpu_ids.c once the ring is up and running, so
nothing reads it during the error-prone part of the initialization.

Fixes: 48e9fbd1a284 ("drm/amdgpu: initialize the vmid_wait with the stub fence")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit f2b96986851203e9c50ca0d13aaa3581ca3e8ebd)
Cc: stable@vger.kernel.org

0 files changed, 0 insertions, 0 deletions