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vxlan: Convert FDB garbage collection to RCU

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Instead of holding the FDB hash lock when traversing the FDB linked list
during garbage collection, use RCU and only acquire the lock for entries
that need to be removed (aged out).

Avoid races by using hlist_unhashed() to check that the entry has not
been removed from the list by another thread.

Note that vxlan_fdb_destroy() uses hlist_del_init_rcu() to remove an
entry from the list which should cause list_unhashed() to return true.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20250415121143.345227-10-idosch@nvidia.com
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Ido Schimmel 2025-04-15 15:11:37 +03:00 committed by Paolo Abeni
parent 7aa0dc750d
commit a6d04f8937
1 changed files with 11 additions and 8 deletions
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19
drivers/net/vxlan/vxlan_core.c
View File

@ -2819,14 +2819,13 @@ static void vxlan_cleanup(struct timer_list *t)
{
struct vxlan_dev *vxlan = from_timer(vxlan, t, age_timer);
unsigned long next_timer = jiffies + FDB_AGE_INTERVAL;
struct hlist_node *n;
struct vxlan_fdb *f;
if (!netif_running(vxlan->dev))
return;
spin_lock(&vxlan->hash_lock);
hlist_for_each_entry_safe(f, n, &vxlan->fdb_list, fdb_node) {
rcu_read_lock();
hlist_for_each_entry_rcu(f, &vxlan->fdb_list, fdb_node) {
unsigned long timeout;
if (f->state & (NUD_PERMANENT | NUD_NOARP))
@ -2837,15 +2836,19 @@ static void vxlan_cleanup(struct timer_list *t)
timeout = READ_ONCE(f->updated) + vxlan->cfg.age_interval * HZ;
if (time_before_eq(timeout, jiffies)) {
netdev_dbg(vxlan->dev, "garbage collect %pM\n",
f->eth_addr);
f->state = NUD_STALE;
vxlan_fdb_destroy(vxlan, f, true, true);
spin_lock(&vxlan->hash_lock);
if (!hlist_unhashed(&f->fdb_node)) {
netdev_dbg(vxlan->dev, "garbage collect %pM\n",
f->eth_addr);
f->state = NUD_STALE;
vxlan_fdb_destroy(vxlan, f, true, true);
}
spin_unlock(&vxlan->hash_lock);
} else if (time_before(timeout, next_timer)) {
next_timer = timeout;
}
}
spin_unlock(&vxlan->hash_lock);
rcu_read_unlock();
mod_timer(&vxlan->age_timer, next_timer);
}