[PATCH 4.5 014/101] net/mlx5_core: Fix soft lockup in steering error flow

Greg Kroah-Hartman
2016-05-17T01:22:16Z

From: Maor Gottlieb <maorg@mellanox.com>

[ Upstream commit c3f9bf628bc7edda298897d952f5e761137229c9 ]

In the error flow of adding flow rule to auto-grouped flow
table, we call to tree_remove_node.

tree_remove_node locks the node's parent, however the node's parent
is already locked by mlx5_add_flow_rule and this causes a deadlock.
After this patch, if we failed to add the flow rule, we unlock the
flow table before calling to tree_remove_node.

fixes: f0d22d187473 ('net/mlx5_core: Introduce flow steering autogrouped
flow table')
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Reported-by: Amir Vadai <amir@vadai.me>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 46 ++++++++--------------
1 file changed, 17 insertions(+), 29 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -957,33 +957,6 @@ unlock_fg:
return rule;
}

-static struct mlx5_flow_rule *add_rule_to_auto_fg(struct mlx5_flow_table *ft,
- u8 match_criteria_enable,
- u32 *match_criteria,
- u32 *match_value,
- u8 action,
- u32 flow_tag,
- struct mlx5_flow_destination *dest)
-{
- struct mlx5_flow_rule *rule;
- struct mlx5_flow_group *g;
-
- g = create_autogroup(ft, match_criteria_enable, match_criteria);
- if (IS_ERR(g))
- return (void *)g;
-
- rule = add_rule_fg(g, match_value,
- action, flow_tag, dest);
- if (IS_ERR(rule)) {
- /* Remove assumes refcount > 0 and autogroup creates a group
- * with a refcount = 0.
- */
- tree_get_node(&g->node);
- tree_remove_node(&g->node);
- }
- return rule;
-}
-
struct mlx5_flow_rule *
mlx5_add_flow_rule(struct mlx5_flow_table *ft,
u8 match_criteria_enable,
@@ -1008,8 +981,23 @@ mlx5_add_flow_rule(struct mlx5_flow_tabl
goto unlock;
}

- rule = add_rule_to_auto_fg(ft, match_criteria_enable, match_criteria,
- match_value, action, flow_tag, dest);
+ g = create_autogroup(ft, match_criteria_enable, match_criteria);
+ if (IS_ERR(g)) {
+ rule = (void *)g;
+ goto unlock;
+ }
+
+ rule = add_rule_fg(g, match_value,
+ action, flow_tag, dest);
+ if (IS_ERR(rule)) {
+ /* Remove assumes refcount > 0 and autogroup creates a group
+ * with a refcount = 0.
+ */
+ unlock_ref_node(&ft->node);
+ tree_get_node(&g->node);
+ tree_remove_node(&g->node);
+ return rule;
+ }
unlock:
unlock_ref_node(&ft->node);
return rule;