From: Tariq Toukan <tariqt@mellanox.com>
Date: Mon, 10 Aug 2020 15:59:41 +0300
Subject: net/mlx5e: kTLS, Fix napi sync and possible use-after-free
Patch-mainline: v5.9-rc7
Git-commit: 6e8de0b6b4690ba7a685db33801bf7536bac674f
References: jsc#SLE-15172

Using synchronize_rcu() is sufficient to wait until running NAPI quits.

See similar upstream fix with detailed explanation:
("net/mlx5e: Use synchronize_rcu to sync with NAPI")

This change also fixes a possible use-after-free as the NAPI
might be already released at this stage.

Fixes: 0419d8c9d8f8 ("net/mlx5e: kTLS, Add kTLS RX resync support")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
@@ -659,7 +659,7 @@ void mlx5e_ktls_del_rx(struct net_device
 	priv_rx = mlx5e_get_ktls_rx_priv_ctx(tls_ctx);
 	set_bit(MLX5E_PRIV_RX_FLAG_DELETING, priv_rx->flags);
 	mlx5e_set_ktls_rx_priv_ctx(tls_ctx, NULL);
-	napi_synchronize(&priv->channels.c[priv_rx->rxq]->napi);
+	synchronize_rcu(); /* Sync with NAPI */
 	if (!cancel_work_sync(&priv_rx->rule.work))
 		/* completion is needed, as the priv_rx in the add flow
 		 * is maintained on the wqe info (wi), not on the socket.