[PATCH batadv v2 6/7] batman-adv: replace non-atomic last_ttvn with (READ|WRITE)_ONCE

The last TT version number of an meshif is only accessed as plain
loads/stores and does not require full atomic_t semantics. Convert to an
native integer and replace its users with READ_ONCE()/WRITE_ONCE() to avoid
load/store tearing.

Signed-off-by: Sven Eckelmann <[email protected]>
---
 net/batman-adv/originator.c        |  2 +-
 net/batman-adv/routing.c           |  4 ++--
 net/batman-adv/send.c              |  2 +-
 net/batman-adv/translation-table.c | 16 ++++++++--------
 net/batman-adv/types.h             |  2 +-
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 5a5cb277..84dfb4fd 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -965,7 +965,7 @@ struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
 	orig_node->bat_priv = bat_priv;
 	ether_addr_copy(orig_node->orig, addr);
 	batadv_dat_init_orig_node_addr(orig_node);
-	atomic_set(&orig_node->last_ttvn, 0);
+	WRITE_ONCE(orig_node->last_ttvn, 0);
 	orig_node->tt_buff = NULL;
 	orig_node->tt_buff_len = 0;
 	orig_node->last_seen = jiffies;
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 1dd295d9..cd4368b8 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -765,7 +765,7 @@ batadv_reroute_unicast_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
 			goto out;
 
 		orig_addr = orig_node->orig;
-		orig_ttvn = (u8)atomic_read(&orig_node->last_ttvn);
+		orig_ttvn = READ_ONCE(orig_node->last_ttvn);
 	}
 
 	/* update the packet header */
@@ -845,7 +845,7 @@ static bool batadv_check_unicast_ttvn(struct batadv_priv *bat_priv,
 		if (!orig_node)
 			return false;
 
-		curr_ttvn = (u8)atomic_read(&orig_node->last_ttvn);
+		curr_ttvn = READ_ONCE(orig_node->last_ttvn);
 		batadv_orig_node_put(orig_node);
 	}
 
diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index c7e86c83..5f9da360 100644
--- a/net/batman-adv/send.c
+++ b/net/batman-adv/send.c
@@ -222,7 +222,7 @@ batadv_send_skb_push_fill_unicast(struct sk_buff *skb, int hdr_size,
 				  struct batadv_orig_node *orig_node)
 {
 	struct batadv_unicast_packet *unicast_packet;
-	u8 ttvn = (u8)atomic_read(&orig_node->last_ttvn);
+	u8 ttvn = READ_ONCE(orig_node->last_ttvn);
 
 	if (batadv_skb_head_push(skb, hdr_size) < 0)
 		return false;
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 382a5826..675338c9 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -880,7 +880,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
 	}
 
 	(*tt_data)->flags = BATADV_NO_FLAGS;
-	(*tt_data)->ttvn = atomic_read(&orig_node->last_ttvn);
+	(*tt_data)->ttvn = READ_ONCE(orig_node->last_ttvn);
 	(*tt_data)->num_vlan = htons(num_vlan);
 
 	tt_vlan = (*tt_data)->vlan_data;
@@ -1861,7 +1861,7 @@ batadv_tt_global_dump_subentry(struct sk_buff *msg, u32 portid, u32 seq,
 	if (!hdr)
 		return -ENOBUFS;
 
-	last_ttvn = atomic_read(&orig->orig_node->last_ttvn);
+	last_ttvn = READ_ONCE(orig->orig_node->last_ttvn);
 
 	if (nla_put(msg, BATADV_ATTR_TT_ADDRESS, ETH_ALEN, common->addr) ||
 	    nla_put(msg, BATADV_ATTR_ORIG_ADDRESS, ETH_ALEN,
@@ -3052,7 +3052,7 @@ static bool batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 	if (!res_dst_orig_node)
 		goto out;
 
-	orig_ttvn = (u8)atomic_read(&req_dst_orig_node->last_ttvn);
+	orig_ttvn = READ_ONCE(req_dst_orig_node->last_ttvn);
 	req_ttvn = tt_data->ttvn;
 
 	/* this node doesn't have the requested data */
@@ -3339,7 +3339,7 @@ static void batadv_tt_fill_gtable(struct batadv_priv *bat_priv,
 	orig_node->tt_buff = NULL;
 	spin_unlock_bh(&orig_node->tt_buff_lock);
 
-	atomic_set(&orig_node->last_ttvn, ttvn);
+	WRITE_ONCE(orig_node->last_ttvn, ttvn);
 
 out:
 	batadv_orig_node_put(orig_node);
@@ -3355,7 +3355,7 @@ static void batadv_tt_update_changes(struct batadv_priv *bat_priv,
 
 	batadv_tt_save_orig_buffer(bat_priv, orig_node, tt_change,
 				   batadv_tt_len(tt_num_changes));
-	atomic_set(&orig_node->last_ttvn, ttvn);
+	WRITE_ONCE(orig_node->last_ttvn, ttvn);
 }
 
 /**
@@ -3808,7 +3808,7 @@ static void batadv_tt_update_orig(struct batadv_priv *bat_priv,
 				  struct batadv_tvlv_tt_change *tt_change,
 				  u16 tt_num_changes, u8 ttvn)
 {
-	u8 orig_ttvn = (u8)atomic_read(&orig_node->last_ttvn);
+	u8 orig_ttvn = READ_ONCE(orig_node->last_ttvn);
 	struct batadv_tvlv_tt_vlan_data *tt_vlan;
 	bool full_table = true;
 	bool has_tt_init;
@@ -3950,7 +3950,7 @@ bool batadv_tt_add_temporary_global_entry(struct batadv_priv *bat_priv,
 
 	if (!batadv_tt_global_add(bat_priv, orig_node, addr, vid,
 				  BATADV_TT_CLIENT_TEMP,
-				  atomic_read(&orig_node->last_ttvn)))
+				  READ_ONCE(orig_node->last_ttvn)))
 		return false;
 
 	batadv_dbg(BATADV_DBG_TT, bat_priv,
@@ -4164,7 +4164,7 @@ static int batadv_roam_tvlv_unicast_handler_v1(struct batadv_priv *bat_priv,
 
 	batadv_tt_global_add(bat_priv, orig_node, roaming_adv->client,
 			     ntohs(roaming_adv->vid), BATADV_TT_CLIENT_ROAM,
-			     atomic_read(&orig_node->last_ttvn) + 1);
+			     READ_ONCE(orig_node->last_ttvn) + 1);
 
 out:
 	batadv_orig_node_put(orig_node);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index d483abb8..154de214 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -443,7 +443,7 @@ struct batadv_orig_node {
 	unsigned long capa_initialized;
 
 	/** @last_ttvn: last seen translation table version number */
-	atomic_t last_ttvn;
+	u8 last_ttvn;
 
 	/** @tt_buff: last tt changeset this node received from the orig node */
 	unsigned char *tt_buff;

-- 
2.47.3