drm/amdgpu: don't drop the gang dependency fence twice

drm_sched_job_add_dependency() drops the fence reference when it fails,
but amdgpu_cs_submit() drops it again, so the scheduled fence of a gang
member loses a reference it still needs.

A GFX+COMPUTE gang waiting for another context, with the
xarray node allocation for the leader's dependency failed through
failslab:

  WARNING: drivers/dma-buf/dma-fence.c:589 at dma_fence_release+0x34d/0x730, CPU#1: amd_uapi_regres/2993
   drm_sched_job_cleanup+0x2c2/0x340 [gpu_sched]
   amdgpu_job_free+0xcb/0x3e0 [amdgpu]
   amdgpu_cs_parser_fini+0x435/0x710 [amdgpu]
   amdgpu_cs_ioctl+0xcd2/0x7a60 [amdgpu]
  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
  RIP: 0010:dma_fence_signal_timestamp_locked+0x1b8/0x610

Fixes: ed21f6c3fe42 ("drm/amdgpu: fix another missing fence reference in the CS code")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 5aa070a83c8378810b906cc8bfc650ce69822a7c)
Cc: stable@vger.kernel.org

0 files changed, 0 insertions, 0 deletions