On 11/09/2016 08:35 AM, Zhiyi Sun wrote:
There are rx_ring_num queues. Each queue will load xdp prog. So
bpf_prog_add() should add rx_ring_num to ref_cnt.
Signed-off-by: Zhiyi Sun <zhiyisun@xxxxxxxxx>
Your analysis looks incorrect to me. Please elaborate in more detail why
you think current code is buggy ...
Call path is dev_change_xdp_fd(), which does bpf_prog_get_type() on the
fd. This already takes a ref and only drops it in case of error. Thus
in mlx4_xdp_set(), you only need priv->rx_ring_num - 1 refs for the rest
of the rings, so that dropping refs from old_prog makes sure we release
it again. Looks correct to me (maybe a comment would have helped there).
drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 12c99a2..d25e150 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -2650,7 +2650,7 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
*/
if (priv->xdp_ring_num == xdp_ring_num) {
if (prog) {
- prog = bpf_prog_add(prog, priv->rx_ring_num - 1);
+ prog = bpf_prog_add(prog, priv->rx_ring_num);
if (IS_ERR(prog))
return PTR_ERR(prog);
}
@@ -2680,7 +2680,7 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
}
if (prog) {
- prog = bpf_prog_add(prog, priv->rx_ring_num - 1);
+ prog = bpf_prog_add(prog, priv->rx_ring_num);
if (IS_ERR(prog))
return PTR_ERR(prog);
}
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