net/mlx5_core: Fix soft lockup in steering error flow

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>

1 files changed, 17 insertions, 29 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 5121be4675d1..3c7e3e581835 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -1065,33 +1065,6 @@ 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;
-}
-
 static struct mlx5_flow_rule *
 _mlx5_add_flow_rule(struct mlx5_flow_table *ft,
                     u8 match_criteria_enable,
@@ -1119,8 +1092,23 @@ _mlx5_add_flow_rule(struct mlx5_flow_table *ft,
                                 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;