Patch "net/mlx5_core: Fix soft lockup in steering error flow" has been added to the 4.5-stable tree

Patch "net/mlx5_core: Fix soft lockup in steering error flow" has been added to the 4.5-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net/mlx5_core: Fix soft lockup in steering error flow

to the 4.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-mlx5_core-fix-soft-lockup-in-steering-error-flow.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon May 16 11:20:33 PDT 2016
From: Maor Gottlieb <maorg@mellanox.com>
Date: Fri, 22 Apr 2016 00:33:00 +0300
Subject: net/mlx5_core: Fix soft lockup in steering error flow

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;


Patches currently in stable-queue which might be from maorg@mellanox.com are

queue-4.5/net-mlx5_core-fix-soft-lockup-in-steering-error-flow.patch