netdev - [PATCH AUTOSEL 5.4 195/205] net/mlx5e: Fix free peer

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Date:   Thu, 16 Jan 2020 11:42:50 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Roi Dayan <roid@...lanox.com>, Eli Britstein <elibr@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 195/205] net/mlx5e: Fix free peer_flow when refcount is 0

From: Roi Dayan <roid@...lanox.com>

[ Upstream commit eb252c3a24fc5856fa62140c2f8269ddce6ce4e5 ]

It could be neigh update flow took a refcount on peer flow so
sometimes we cannot release peer flow even if parent flow is
being freed now.

Fixes: 5a7e5bcb663d ("net/mlx5e: Extend tc flow struct with reference counter")
Signed-off-by: Roi Dayan <roid@...lanox.com>
Reviewed-by: Eli Britstein <elibr@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 947122c68493..96711e34d248 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -1615,8 +1615,11 @@ static void __mlx5e_tc_del_fdb_peer_flow(struct mlx5e_tc_flow *flow)
 
 	flow_flag_clear(flow, DUP);
 
-	mlx5e_tc_del_fdb_flow(flow->peer_flow->priv, flow->peer_flow);
-	kfree(flow->peer_flow);
+	if (refcount_dec_and_test(&flow->peer_flow->refcnt)) {
+		mlx5e_tc_del_fdb_flow(flow->peer_flow->priv, flow->peer_flow);
+		kfree(flow->peer_flow);
+	}
+
 	flow->peer_flow = NULL;
 }
 
-- 
2.20.1