From 05be0d3f8060faf8f2e3cbf7a0f40730be43b7f7 Mon Sep 17 00:00:00 2001 From: Simon Wunderlich Date: Thu, 11 Jun 2015 18:37:57 +0200 Subject: [PATCH 1/2] batman-adv: lock crc access in bridge loop avoidance To avoid multiple functions changing a backbone gateways crc entry, lock it using a spinlock. Signed-off-by: Simon Wunderlich --- bridge_loop_avoidance.c | 35 ++++++++++++++++++++++++++++++----- types.h | 2 ++ 2 files changed, 32 insertions(+), 5 deletions(-) diff --git a/bridge_loop_avoidance.c b/bridge_loop_avoidance.c index a957c81..07d0753 100644 --- a/bridge_loop_avoidance.c +++ b/bridge_loop_avoidance.c @@ -246,7 +246,9 @@ batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw) } /* all claims gone, intialize CRC */ + spin_lock_bh(&backbone_gw->crc_lock); backbone_gw->crc = BATADV_BLA_CRC_INIT; + spin_unlock_bh(&backbone_gw->crc_lock); } /** @@ -393,6 +395,7 @@ batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, uint8_t *orig, entry->lasttime = jiffies; entry->crc = BATADV_BLA_CRC_INIT; entry->bat_priv = bat_priv; + spin_lock_init(&entry->crc_lock); atomic_set(&entry->request_sent, 0); atomic_set(&entry->wait_periods, 0); ether_addr_copy(entry->orig, orig); @@ -541,7 +544,9 @@ static void batadv_bla_send_announce(struct batadv_priv *bat_priv, __be16 crc; memcpy(mac, batadv_announce_mac, 4); + spin_lock_bh(&backbone_gw->crc_lock); crc = htons(backbone_gw->crc); + spin_unlock_bh(&backbone_gw->crc_lock); memcpy(&mac[4], &crc, 2); batadv_bla_send_claim(bat_priv, mac, backbone_gw->vid, @@ -602,14 +607,18 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, "bla_add_claim(): changing ownership for %pM, vid %d\n", mac, BATADV_PRINT_VID(vid)); + spin_lock_bh(&claim->backbone_gw->crc_lock); claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); + spin_unlock_bh(&claim->backbone_gw->crc_lock); batadv_backbone_gw_free_ref(claim->backbone_gw); } /* set (new) backbone gw */ atomic_inc(&backbone_gw->refcount); claim->backbone_gw = backbone_gw; + spin_lock_bh(&backbone_gw->crc_lock); backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); + spin_unlock_bh(&backbone_gw->crc_lock); backbone_gw->lasttime = jiffies; claim_free_ref: @@ -637,7 +646,9 @@ static void batadv_bla_del_claim(struct batadv_priv *bat_priv, batadv_choose_claim, claim); batadv_claim_free_ref(claim); /* reference from the hash is gone */ + spin_lock_bh(&claim->backbone_gw->crc_lock); claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); + spin_unlock_bh(&claim->backbone_gw->crc_lock); /* don't need the reference from hash_find() anymore */ batadv_claim_free_ref(claim); @@ -649,7 +660,7 @@ static int batadv_handle_announce(struct batadv_priv *bat_priv, unsigned short vid) { struct batadv_bla_backbone_gw *backbone_gw; - uint16_t crc; + uint16_t backbone_crc, crc; if (memcmp(an_addr, batadv_announce_mac, 4) != 0) return 0; @@ -669,12 +680,16 @@ static int batadv_handle_announce(struct batadv_priv *bat_priv, "handle_announce(): ANNOUNCE vid %d (sent by %pM)... CRC = %#.4x\n", BATADV_PRINT_VID(vid), backbone_gw->orig, crc); - if (backbone_gw->crc != crc) { + spin_lock_bh(&backbone_gw->crc_lock); + backbone_crc = backbone_gw->crc; + spin_unlock_bh(&backbone_gw->crc_lock); + + if (backbone_crc != crc) { batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv, "handle_announce(): CRC FAILED for %pM/%d (my = %#.4x, sent = %#.4x)\n", backbone_gw->orig, BATADV_PRINT_VID(backbone_gw->vid), - backbone_gw->crc, crc); + backbone_crc, crc); batadv_bla_send_request(backbone_gw); } else { @@ -1636,6 +1651,7 @@ int batadv_bla_claim_table_seq_print_text(struct seq_file *seq, void *offset) struct batadv_bla_claim *claim; struct batadv_hard_iface *primary_if; struct hlist_head *head; + uint16_t backbone_crc; uint32_t i; bool is_own; uint8_t *primary_addr; @@ -1658,11 +1674,15 @@ int batadv_bla_claim_table_seq_print_text(struct seq_file *seq, void *offset) hlist_for_each_entry_rcu(claim, head, hash_entry) { is_own = batadv_compare_eth(claim->backbone_gw->orig, primary_addr); + + spin_lock_bh(&claim->backbone_gw->crc_lock); + backbone_crc = claim->backbone_gw->crc; + spin_lock_bh(&claim->backbone_gw->crc_lock); seq_printf(seq, " * %pM on %5d by %pM [%c] (%#.4x)\n", claim->addr, BATADV_PRINT_VID(claim->vid), claim->backbone_gw->orig, (is_own ? 'x' : ' '), - claim->backbone_gw->crc); + backbone_crc); } rcu_read_unlock(); } @@ -1682,6 +1702,7 @@ int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq, void *offset) struct hlist_head *head; int secs, msecs; uint32_t i; + uint16_t backbone_crc; bool is_own; uint8_t *primary_addr; @@ -1711,10 +1732,14 @@ int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq, void *offset) if (is_own) continue; + spin_lock_bh(&backbone_gw->crc_lock); + backbone_crc = backbone_gw->crc; + spin_unlock_bh(&backbone_gw->crc_lock); + seq_printf(seq, " * %pM on %5d %4i.%03is (%#.4x)\n", backbone_gw->orig, BATADV_PRINT_VID(backbone_gw->vid), secs, - msecs, backbone_gw->crc); + msecs, backbone_crc); } rcu_read_unlock(); } diff --git a/types.h b/types.h index 8854c05..fb7e10e 100644 --- a/types.h +++ b/types.h @@ -868,6 +868,7 @@ struct batadv_socket_packet { * backbone gateway - no bcast traffic is formwared until the situation was * resolved * @crc: crc16 checksum over all claims + * @crc_lock: lock protecting crc * @refcount: number of contexts the object is used * @rcu: struct used for freeing in an RCU-safe manner */ @@ -881,6 +882,7 @@ struct batadv_bla_backbone_gw { atomic_t wait_periods; atomic_t request_sent; uint16_t crc; + spinlock_t crc_lock; atomic_t refcount; struct rcu_head rcu; }; -- 2.1.4