Couple of BPF refcount fixes for mlx5

Various mlx5 bugs on eBPF refcount handling found during review. Last patch in series adds a __must_check to BPF helpers to make sure we won't run into it again w/o compiler complaining first.

v2 -> v3:

- Just reworked patch 2/4 so we don't need bpf_prog_sub().
- Rebased, rest as is.

v1 -> v2:

- After discussion with Alexei, we agreed upon rebasing the patches against net-next.
- Since net-next, I've also added the __must_check to enforce future users to check for errors.
- Fixed up commit message #2.
- Simplify assignment from patch #1 based on Saeed's feedback on previous set.

Thanks a lot!

Daniel Borkmann (4):
bpf, mlx5: fix mlx5e_create_rq taking reference on prog bpf, mlx5: fix various refcount issues in mlx5e_xdp_set bpf, mlx5: drop priv->xdp_prog reference on netdev cleanup
bpf: add __must_check attributes to refcount manipulating helpers

 drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 33 +++++++++++++++++------
 include/linux/bpf.h                               | 12 +++++----
 kernel/bpf/syscall.c                              |  1 +
 3 files changed, 33 insertions(+), 13 deletions(-)

1.9.3