From: Vlad Buslov <vladbu@mellanox.com>
Date: Fri, 8 Jun 2018 22:10:09 +0300
Subject: net/mlx5e: Protect mod header entry flows list with spinlock
Patch-mainline: v5.4-rc1
Git-commit: 83a52f0d525587de65b2bc979a12b4dfad9ea82a
References: jsc#SLE-8464

To remove dependency on rtnl lock, extend mod header entry with spinlock
and use it to protect list of flows attached to mod header entry from
concurrent modifications.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -189,6 +189,8 @@ struct mlx5e_mod_hdr_entry {
 	/* a node of a hash table which keeps all the mod_hdr entries */
 	struct hlist_node mod_hdr_hlist;
 
+	/* protects flows list */
+	spinlock_t flows_lock;
 	/* flows sharing the same mod_hdr entry */
 	struct list_head flows;
 
@@ -358,6 +360,7 @@ static int mlx5e_attach_mod_hdr(struct m
 	mh->key.actions = (void *)mh + sizeof(*mh);
 	memcpy(mh->key.actions, key.actions, actions_size);
 	mh->key.num_actions = num_actions;
+	spin_lock_init(&mh->flows_lock);
 	INIT_LIST_HEAD(&mh->flows);
 	refcount_set(&mh->refcnt, 1);
 
@@ -372,7 +375,9 @@ static int mlx5e_attach_mod_hdr(struct m
 
 attach_flow:
 	flow->mh = mh;
+	spin_lock(&mh->flows_lock);
 	list_add(&flow->mod_hdr, &mh->flows);
+	spin_unlock(&mh->flows_lock);
 	if (is_eswitch_flow)
 		flow->esw_attr->mod_hdr_id = mh->mod_hdr_id;
 	else
@@ -392,7 +397,9 @@ static void mlx5e_detach_mod_hdr(struct
 	if (!flow->mh)
 		return;
 
+	spin_lock(&flow->mh->flows_lock);
 	list_del(&flow->mod_hdr);
+	spin_unlock(&flow->mh->flows_lock);
 
 	mlx5e_mod_hdr_put(priv, flow->mh);
 	flow->mh = NULL;