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neighbour: add RCU protection to neigh_tables[]

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In order to remove RTNL protection from neightbl_dump_info()
and neigh_dump_info() later, we need to add
RCU protection to neigh_tables[].

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-04-18 09:51:04 +00:00 committed by David S. Miller
parent 9fc31a9251
commit f8f2eb9de6
1 changed files with 19 additions and 11 deletions
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30
net/core/neighbour.c
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@ -1771,7 +1771,7 @@ static void neigh_parms_destroy(struct neigh_parms *parms)
static struct lock_class_key neigh_table_proxy_queue_class;
static struct neigh_table *neigh_tables[NEIGH_NR_TABLES] __read_mostly;
static struct neigh_table __rcu *neigh_tables[NEIGH_NR_TABLES] __read_mostly;
void neigh_table_init(int index, struct neigh_table *tbl)
{
@ -1828,13 +1828,19 @@ void neigh_table_init(int index, struct neigh_table *tbl)
tbl->last_flush = now;
tbl->last_rand = now + tbl->parms.reachable_time * 20;
neigh_tables[index] = tbl;
rcu_assign_pointer(neigh_tables[index], tbl);
}
EXPORT_SYMBOL(neigh_table_init);
/*
* Only called from ndisc_cleanup(), which means this is dead code
* because we no longer can unload IPv6 module.
*/
int neigh_table_clear(int index, struct neigh_table *tbl)
{
neigh_tables[index] = NULL;
RCU_INIT_POINTER(neigh_tables[index], NULL);
synchronize_rcu();
/* It is not clean... Fix it to unload IPv6 module safely */
cancel_delayed_work_sync(&tbl->managed_work);
cancel_delayed_work_sync(&tbl->gc_work);
@ -1866,10 +1872,10 @@ static struct neigh_table *neigh_find_table(int family)
switch (family) {
case AF_INET:
tbl = neigh_tables[NEIGH_ARP_TABLE];
tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ARP_TABLE]);
break;
case AF_INET6:
tbl = neigh_tables[NEIGH_ND_TABLE];
tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ND_TABLE]);
break;
}
@ -2333,7 +2339,7 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
ndtmsg = nlmsg_data(nlh);
for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
tbl = neigh_tables[tidx];
tbl = rcu_dereference_rtnl(neigh_tables[tidx]);
if (!tbl)
continue;
if (ndtmsg->ndtm_family && tbl->family != ndtmsg->ndtm_family)
@ -2521,7 +2527,7 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
struct neigh_parms *p;
tbl = neigh_tables[tidx];
tbl = rcu_dereference_rtnl(neigh_tables[tidx]);
if (!tbl)
continue;
@ -2881,7 +2887,7 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
s_t = cb->args[0];
for (t = 0; t < NEIGH_NR_TABLES; t++) {
tbl = neigh_tables[t];
tbl = rcu_dereference_rtnl(neigh_tables[t]);
if (!tbl)
continue;
@ -3145,14 +3151,15 @@ int neigh_xmit(int index, struct net_device *dev,
const void *addr, struct sk_buff *skb)
{
int err = -EAFNOSUPPORT;
if (likely(index < NEIGH_NR_TABLES)) {
struct neigh_table *tbl;
struct neighbour *neigh;
tbl = neigh_tables[index];
if (!tbl)
goto out;
rcu_read_lock();
tbl = rcu_dereference(neigh_tables[index]);
if (!tbl)
goto out_unlock;
if (index == NEIGH_ARP_TABLE) {
u32 key = *((u32 *)addr);
@ -3168,6 +3175,7 @@ int neigh_xmit(int index, struct net_device *dev,
goto out_kfree_skb;
}
err = READ_ONCE(neigh->output)(neigh, skb);
out_unlock:
rcu_read_unlock();
}
else if (index == NEIGH_LINK_TABLE) {