Commit 3b2582c7 authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Simon Wunderlich
Browse files

batman-adv: Avoid RCU list-traversal in spinlock 



The new CONFIG_PROVE_RCU_LIST requires a condition statement in
(h)list_for_each_entry_rcu when the code might be executed in a non RCU
non-reader section with the writer lock. Otherwise lockdep might cause a
false positive warning like

  =============================
  WARNING: suspicious RCU usage
  -----------------------------
  translation-table.c:940 RCU-list traversed in non-reader section!!

batman-adv is (mostly) following the examples from the RCU documentation
and is using the normal list-traversal primitives instead of the RCU
list-traversal primitives when the writer (spin)lock is held.

The remaining users of RCU list-traversal primitives with writer spinlock
have to be converted to the same style as the rest of the code.

Reported-by: default avatarMadhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
parent edddb366

net/batman-adv/translation-table.c

+4 −4
Original line number Diff line number Diff line
@@ -862,7 +862,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, 
	u8 *tt_change_ptr;



	spin_lock_bh(&orig_node->vlan_list_lock);

	hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {

	hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {

		num_vlan++;

		num_entries += atomic_read(&vlan->tt.num_entries);

	}
@@ -888,7 +888,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, 
	(*tt_data)->num_vlan = htons(num_vlan);



	tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1);

	hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {

	hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {

		tt_vlan->vid = htons(vlan->vid);

		tt_vlan->crc = htonl(vlan->tt.crc);
@@ -937,7 +937,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, 
	int change_offset;



	spin_lock_bh(&bat_priv->softif_vlan_list_lock);

	hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) {

	hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) {

		vlan_entries = atomic_read(&vlan->tt.num_entries);

		if (vlan_entries < 1)

			continue;
@@ -967,7 +967,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, 
	(*tt_data)->num_vlan = htons(num_vlan);



	tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1);

	hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) {

	hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) {

		vlan_entries = atomic_read(&vlan->tt.num_entries);

		if (vlan_entries < 1)

			continue;

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