On 11/16/2016 04:45 PM, Daniel Borkmann wrote:
On 11/16/2016 01:51 PM, Saeed Mahameed wrote:
On Wed, Nov 16, 2016 at 2:04 AM, Daniel Borkmann <dan...@iogearbox.net> wrote:
mlx5e_xdp_set() is currently the only place where we drop reference on the
prog sitting in priv->xdp_prog when it's exchanged by a new one. We also
need to make sure that we eventually release that reference, for example,
in case the netdev is dismantled.

Fixes: 86994156c736 ("net/mlx5e: XDP fast RX drop bpf programs support")
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
---
  drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index cf26672..60fe54c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3715,6 +3715,9 @@ static void mlx5e_nic_cleanup(struct mlx5e_priv *priv)

         if (MLX5_CAP_GEN(mdev, vport_group_manager))
                 mlx5_eswitch_unregister_vport_rep(esw, 0);
+
+       if (priv->xdp_prog)
+               bpf_prog_put(priv->xdp_prog);
  }

I thought that on unregister_netdev  ndo_xdp_set will be called with
NULL prog to cleanup. like any other resources (Vlans/mac_lists/
etc..), why xdp should be different ?
Anyway if this is the case, I am ok with this fix, you can even send
it to net (it looks like a serious leak).

The only interaction with ndo_xdp() right now is dev_change_xdp_fd()
and the currently a bit terse dump via rtnl_xdp_fill(). The latter
only tells whether something is actually attached and will have more
info in near future, but doesn't alter anything.

dev_change_xdp_fd() is only triggered from user side via netlink when
IFLA_XDP container attr is around, so no automatic cleanup here. This
means as per documentation in enum xdp_netdev_command, that the driver
has full ownership, thus needs to bpf_prog_put().

Note that without patch 2/4, just sending this one to net doesn't really
solve anything, since there the mlx5e_xdp_set() still has the incorrect
bpf_prog_add(prog, 1) around. So it's the whole series if so. I had it
originally targeted at net, but Alexei suggested net-next; I don't really
mind either way, so I agreed to go for net-next.

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