releases/5.4.295/net-mlx5-wait-for-inactive-autogroups.patch

From cd6d5cdc02c52ffec8dc01caeda3733baef69a9b Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 7 May 2020 12:01:39 +0300
Subject: net/mlx5: Wait for inactive autogroups

From: Paul Blakey <paulb@mellanox.com>

[ Upstream commit 49c0355d301b4e0e01e0f19ddbb023bd7d0ee48c ]

Currently, if one thread tries to add an entry to an autogrouped table
with no free matching group, while another thread is in the process of
creating a new matching autogroup, it doesn't wait for the new group
creation, and creates an unnecessary new autogroup.

Instead of skipping inactive, wait on the write lock of those groups.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Stable-dep-of: 8ec40e3f1f72 ("net/mlx5: Fix return value when searching for existing flow group")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 30d5b7f52a2a0..25f9185d5a15e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -1768,11 +1768,13 @@ try_add_to_existing_fg(struct mlx5_flow_table *ft,
 	list_for_each_entry(iter, match_head, list) {
 		g = iter->g;
 
-		if (!g->node.active)
-			continue;
-
 		nested_down_write_ref_node(&g->node, FS_LOCK_PARENT);
 
+		if (!g->node.active) {
+			up_write_ref_node(&g->node, false);
+			continue;
+		}
+
 		err = insert_fte(g, fte);
 		if (err) {
 			up_write_ref_node(&g->node, false);
-- 
2.39.5