The lasttime field for claim, backbone_gw, and loopdetect tracks the
jiffies value of the most recent activity and is used to detect timeouts.
These accesses are not consistently protected by a lock, so
READ_ONCE/WRITE_ONCE must be used to prevent data races caused by compiler
optimizations.
Fixes: a9ce0dc43e2c ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <[email protected]>
---
net/batman-adv/bridge_loop_avoidance.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/net/batman-adv/bridge_loop_avoidance.c
b/net/batman-adv/bridge_loop_avoidance.c
index ffe85401..7f643de4 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -512,7 +512,7 @@ batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv,
const u8 *orig,
return NULL;
entry->vid = vid;
- entry->lasttime = jiffies;
+ WRITE_ONCE(entry->lasttime, jiffies);
entry->crc = BATADV_BLA_CRC_INIT;
entry->bat_priv = bat_priv;
spin_lock_init(&entry->crc_lock);
@@ -580,7 +580,7 @@ batadv_bla_update_own_backbone_gw(struct batadv_priv
*bat_priv,
if (unlikely(!backbone_gw))
return;
- backbone_gw->lasttime = jiffies;
+ WRITE_ONCE(backbone_gw->lasttime, jiffies);
batadv_backbone_gw_put(backbone_gw);
}
@@ -714,7 +714,7 @@ static void batadv_bla_add_claim(struct batadv_priv
*bat_priv,
ether_addr_copy(claim->addr, mac);
spin_lock_init(&claim->backbone_lock);
claim->vid = vid;
- claim->lasttime = jiffies;
+ WRITE_ONCE(claim->lasttime, jiffies);
kref_get(&backbone_gw->refcount);
claim->backbone_gw = backbone_gw;
kref_init(&claim->refcount);
@@ -736,7 +736,7 @@ static void batadv_bla_add_claim(struct batadv_priv
*bat_priv,
return;
}
} else {
- claim->lasttime = jiffies;
+ WRITE_ONCE(claim->lasttime, jiffies);
if (claim->backbone_gw == backbone_gw)
/* no need to register a new backbone */
goto claim_free_ref;
@@ -769,7 +769,7 @@ static void batadv_bla_add_claim(struct batadv_priv
*bat_priv,
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;
+ WRITE_ONCE(backbone_gw->lasttime, jiffies);
claim_free_ref:
batadv_claim_put(claim);
@@ -858,7 +858,7 @@ static bool batadv_handle_announce(struct batadv_priv
*bat_priv, u8 *an_addr,
return true;
/* handle as ANNOUNCE frame */
- backbone_gw->lasttime = jiffies;
+ WRITE_ONCE(backbone_gw->lasttime, jiffies);
crc = ntohs(*((__force __be16 *)(&an_addr[4])));
batadv_dbg(BATADV_DBG_BLA, bat_priv,
@@ -1253,7 +1253,7 @@ static void batadv_bla_purge_backbone_gw(struct
batadv_priv *bat_priv, int now)
head, hash_entry) {
if (now)
goto purge_now;
- if (!batadv_has_timed_out(backbone_gw->lasttime,
+ if
(!batadv_has_timed_out(READ_ONCE(backbone_gw->lasttime),
BATADV_BLA_BACKBONE_TIMEOUT))
continue;
@@ -1334,7 +1334,7 @@ static void batadv_bla_purge_claims(struct batadv_priv
*bat_priv,
primary_if->net_dev->dev_addr))
goto skip;
- if (!batadv_has_timed_out(claim->lasttime,
+ if (!batadv_has_timed_out(READ_ONCE(claim->lasttime),
BATADV_BLA_CLAIM_TIMEOUT))
goto skip;
@@ -1494,7 +1494,7 @@ static void batadv_bla_periodic_work(struct work_struct
*work)
eth_random_addr(bat_priv->bla.loopdetect_addr);
bat_priv->bla.loopdetect_addr[0] = 0xba;
bat_priv->bla.loopdetect_addr[1] = 0xbe;
- bat_priv->bla.loopdetect_lasttime = jiffies;
+ WRITE_ONCE(bat_priv->bla.loopdetect_lasttime, jiffies);
atomic_set(&bat_priv->bla.loopdetect_next,
BATADV_BLA_LOOPDETECT_PERIODS);
@@ -1515,7 +1515,7 @@ static void batadv_bla_periodic_work(struct work_struct
*work)
primary_if->net_dev->dev_addr))
continue;
- backbone_gw->lasttime = jiffies;
+ WRITE_ONCE(backbone_gw->lasttime, jiffies);
batadv_bla_send_announce(bat_priv, backbone_gw);
if (send_loopdetect)
@@ -1899,7 +1899,7 @@ batadv_bla_loopdetect_check(struct batadv_priv *bat_priv,
struct sk_buff *skb,
/* If the packet came too late, don't forward it on the mesh
* but don't consider that as loop. It might be a coincidence.
*/
- if (batadv_has_timed_out(bat_priv->bla.loopdetect_lasttime,
+ if (batadv_has_timed_out(READ_ONCE(bat_priv->bla.loopdetect_lasttime),
BATADV_BLA_LOOPDETECT_TIMEOUT))
return true;
@@ -2014,7 +2014,7 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct
sk_buff *skb,
if (own_claim) {
/* ... allow it in any case */
- claim->lasttime = jiffies;
+ WRITE_ONCE(claim->lasttime, jiffies);
goto allow;
}
@@ -2116,7 +2116,7 @@ bool batadv_bla_tx(struct batadv_priv *bat_priv, struct
sk_buff *skb,
/* if yes, the client has roamed and we have
* to unclaim it.
*/
- if (batadv_has_timed_out(claim->lasttime, 100)) {
+ if (batadv_has_timed_out(READ_ONCE(claim->lasttime), 100)) {
/* only unclaim if the last claim entry is
* older than 100 ms to make sure we really
* have a roaming client here.
@@ -2361,7 +2361,7 @@ batadv_bla_backbone_dump_entry(struct sk_buff *msg, u32
portid,
backbone_crc = backbone_gw->crc;
spin_unlock_bh(&backbone_gw->crc_lock);
- msecs = jiffies_to_msecs(jiffies - backbone_gw->lasttime);
+ msecs = jiffies_to_msecs(jiffies - READ_ONCE(backbone_gw->lasttime));
if (is_own)
if (nla_put_flag(msg, BATADV_ATTR_BLA_OWN)) {
---
base-commit: ec9f686b42917e9b67725d7245b50de72f59fa9e
change-id: 20260526-lasttime-once-6a32cea79eb2
Best regards,
--
Sven Eckelmann <[email protected]>
