diff mbox

batman-adv: lock crc access in bridge loop avoidance

Message ID 1441385723-5565-1-git-send-email-sw@simonwunderlich.de (mailing list archive)
State Superseded, archived
Headers

Commit Message

Simon Wunderlich Sept. 4, 2015, 4:55 p.m. UTC 
  To avoid multiple functions changing a backbone gateways crc entry, lock
it using a spinlock.

Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Tested-by: Alfons Name <AlfonsName@web.de>
---
 net/batman-adv/bridge_loop_avoidance.c | 35 +++++++++++++++++++++++++++++-----
 net/batman-adv/types.h                 |  2 ++
 2 files changed, 32 insertions(+), 5 deletions(-)

Comments

Marek Lindner Sept. 6, 2015, 8:14 a.m. UTC | #1 
On Friday, September 04, 2015 18:55:23 Simon Wunderlich wrote:
> To avoid multiple functions changing a backbone gateways crc entry, lock
> it using a spinlock.

Feels like maint/stable material to me ? If so, we need a more screaming 
commit message to get the stable patch through the lines.


Cheers,
Marek
diff mbox

Patch

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 191a702..c80b015 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_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();
 	}
@@ -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();
 	}
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 9bdb21c..7c386db 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -906,6 +906,7 @@  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
  */
@@ -919,6 +920,7 @@  struct batadv_bla_backbone_gw {
 	atomic_t wait_periods;
 	atomic_t request_sent;
 	u16 crc;
+	spinlock_t crc_lock; /* protects crc */
 	atomic_t refcount;
 	struct rcu_head rcu;
 };