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authorSimon Wunderlich <sw@simonwunderlich.de>2015-09-11 19:04:13 +0300
committerAntonio Quartulli <a@unstable.cc>2015-12-16 10:17:09 +0300
commit5a1dd8a4773d4c24e925cc6154826d555a85c370 (patch)
tree60e9944e19fe8b52ef0e63667eb8af7cb7b85662 /net/batman-adv/bridge_loop_avoidance.c
parentc05a57f6fb6f398cde873c5ebe13ae26b3843b7e (diff)
downloadlinux-5a1dd8a4773d4c24e925cc6154826d555a85c370.tar.xz
batman-adv: lock crc access in bridge loop avoidance
We have found some networks in which nodes were constantly requesting other nodes BLA claim tables to synchronize, just to ask for that again once completed. The reason was that the crc checksum of the asked nodes were out of sync due to missing locking and multiple writes to the same crc checksum when adding/removing entries. Therefore the asked nodes constantly reported the wrong crc, which caused repeating requests. To avoid multiple functions changing a backbone gateways crc entry at the same time, lock it using a spinlock. Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de> Tested-by: Alfons Name <AlfonsName@web.de> Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch> Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Diffstat (limited to 'net/batman-adv/bridge_loop_avoidance.c')
-rw-r--r--net/batman-adv/bridge_loop_avoidance.c35
1 files changed, 30 insertions, 5 deletions
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 191a70290dca..99dcae316ec8 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -260,7 +260,9 @@ batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw)
}
/* all claims gone, initialize CRC */
+ spin_lock_bh(&backbone_gw->crc_lock);
backbone_gw->crc = BATADV_BLA_CRC_INIT;
+ spin_unlock_bh(&backbone_gw->crc_lock);
}
/**
@@ -408,6 +410,7 @@ batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, u8 *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);
@@ -557,7 +560,9 @@ 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,
@@ -618,14 +623,18 @@ 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:
@@ -653,7 +662,9 @@ 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);
@@ -664,7 +675,7 @@ static int batadv_handle_announce(struct batadv_priv *bat_priv, u8 *an_addr,
u8 *backbone_addr, unsigned short vid)
{
struct batadv_bla_backbone_gw *backbone_gw;
- u16 crc;
+ u16 backbone_crc, crc;
if (memcmp(an_addr, batadv_announce_mac, 4) != 0)
return 0;
@@ -683,12 +694,16 @@ static int batadv_handle_announce(struct batadv_priv *bat_priv, u8 *an_addr,
"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 {
@@ -1647,6 +1662,7 @@ 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;
+ u16 backbone_crc;
u32 i;
bool is_own;
u8 *primary_addr;
@@ -1669,11 +1685,15 @@ 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_unlock_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();
}
@@ -1692,6 +1712,7 @@ int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq, void *offset)
struct batadv_hard_iface *primary_if;
struct hlist_head *head;
int secs, msecs;
+ u16 backbone_crc;
u32 i;
bool is_own;
u8 *primary_addr;
@@ -1722,10 +1743,14 @@ 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();
}