Le 27/09/2026 à 02:24, Yuyang Huang a écrit :
> A multi-part RTM_GETMULTICAST dump of dev->mc resumes by position, so
> entries added or removed between two dump rounds can be skipped or
> repeated. The IPv4 and IPv6 dumps report that with NLM_F_DUMP_INTR by
> stamping cb->seq from a per netns generation counter combined with
> dev_base_seq, see inet_base_seq().
>
> Add the equivalent for the device multicast lists: a per netns counter
> bumped whenever an entry is added to or removed from any dev->mc. The
> list helpers do not know which device a list belongs to, so give
> netdev_hw_addr_list an owner, set for the lists of a device and NULL
> for snapshots and other standalone lists, and change list->count
> through helpers that bump the counter of dev_net(owner) when the list
> is dev->mc. That covers the dev_mc_* helpers, both lists of a sync,
> the hardware sync helpers drivers call from their rx mode callbacks or
> their own workers and the reconciliation after an asynchronous rx mode
> update. It is atomic since the writers only hold the address lock of
> their own device.
>
> Used by the following patch for the AF_PACKET multicast dump.
>
> Signed-off-by: Yuyang Huang <[email protected]>
If another version is needed, you can rename counter to _counter to highlight
that the helpers should be used.
> ---
> include/linux/netdevice.h | 5 ++++
> include/net/net_namespace.h | 1 +
> net/core/dev_addr_lists.c | 52 +++++++++++++++++++++++++++++++------
> 3 files changed, 50 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index d037faff7c44..69d1cde0a38a 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -256,6 +256,11 @@ struct netdev_hw_addr_list {
>
> /* Auxiliary tree for faster lookup on addition and deletion */
> struct rb_root tree;
> +
> + /* The device a list belongs to, NULL for snapshots and other
> + * standalone lists
> + */
> + struct net_device *owner;
> };
>
> #define netdev_hw_addr_list_count(l) ((l)->count)
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index 46b4c67e2966..d8c681ab5c74 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -71,6 +71,7 @@ struct net {
> spinlock_t rules_mod_lock;
>
> unsigned int dev_base_seq; /* protected by rtnl_mutex */
> + atomic_t dev_mc_genid; /* bumped on dev->mc changes */
> u32 ifindex;
>
> spinlock_t nsid_lock;
> diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
> index 08528ca0a8b3..c941c3ec1007 100644
> --- a/net/core/dev_addr_lists.c
> +++ b/net/core/dev_addr_lists.c
> @@ -16,6 +16,37 @@
>
> #include "dev.h"
>
> +/* Only dev->mc is tracked, RTM_GETMULTICAST dumps use the netns generation
> + * counter to detect changes between dump rounds.
> + */
> +static void __hw_addr_changed(struct netdev_hw_addr_list *list)
> +{
> + struct net_device *dev = list->owner;
> +
> + if (dev && list == &dev->mc)
> + atomic_inc(&dev_net(dev)->dev_mc_genid);
> +}
> +
> +static void __hw_addr_count_inc(struct netdev_hw_addr_list *list)
static void __hw_addr_count_add(struct netdev_hw_addr_list *list, int value)
> +{
> + list->count++;
list->count += value;> + __hw_addr_changed(list);
> +}
#define __hw_addr_count_inc(l) __hw_addr_count_add(l, 1)
> +
> +static void __hw_addr_count_dec(struct netdev_hw_addr_list *list)
> +{
> + list->count--;
> + __hw_addr_changed(list);
> +}
> +
> +static void __hw_addr_count_reset(struct netdev_hw_addr_list *list)
> +{
> + if (!list->count)
> + return;
> + list->count = 0;
> + __hw_addr_changed(list);
> +}
> +
> /*
> * General list handling functions
> */
> @@ -125,7 +156,7 @@ static int __hw_addr_add_ex(struct netdev_hw_addr_list
> *list,
> rb_insert_color(&ha->node, &list->tree);
>
> list_add_tail_rcu(&ha->list, &list->list);
> - list->count++;
> + __hw_addr_count_inc(list);
>
> return 0;
> }
> @@ -161,7 +192,7 @@ static int __hw_addr_del_entry(struct netdev_hw_addr_list
> *list,
>
> list_del_rcu(&ha->list);
> kfree_rcu(ha, rcu_head);
> - list->count--;
> + __hw_addr_count_dec(list);
> return 0;
> }
>
> @@ -492,7 +523,7 @@ void __hw_addr_flush(struct netdev_hw_addr_list *list)
> list_del_rcu(&ha->list);
> kfree_rcu(ha, rcu_head);
> }
> - list->count = 0;
> + __hw_addr_count_reset(list);
> }
> EXPORT_SYMBOL_IF_KUNIT(__hw_addr_flush);
>
> @@ -501,6 +532,7 @@ void __hw_addr_init(struct netdev_hw_addr_list *list)
> INIT_LIST_HEAD(&list->list);
> list->count = 0;
> list->tree = RB_ROOT;
> + list->owner = NULL;
> }
> EXPORT_SYMBOL(__hw_addr_init);
For correctness, __hw_addr_splice() should use helper:
@@ -509,8 +509,8 @@ static void __hw_addr_splice(struct netdev_hw_addr_list
*dst,
{
src->tree = RB_ROOT;
list_splice_init(&src->list, &dst->list);
- dst->count += src->count;
- src->count = 0;
+ __hw_addr_count_add(dst, src->count);
+ __hw_addr_count_reset(src);
}
Renaming struct netdev_hw_addr_list->count to _count would help to check all
users and highlight that modifying _count should be done with helpers.
>
> @@ -536,7 +568,7 @@ int __hw_addr_list_snapshot(struct netdev_hw_addr_list
> *snap,
> entry = list_first_entry(&cache->list,
> struct netdev_hw_addr, list);
> list_del(&entry->list);
> - cache->count--;
> + __hw_addr_count_dec(cache);
> memcpy(entry->addr, ha->addr, addr_len);
> entry->type = ha->type;
> entry->global_use = false;
> @@ -554,7 +586,7 @@ int __hw_addr_list_snapshot(struct netdev_hw_addr_list
> *snap,
>
> list_add_tail(&entry->list, &snap->list);
> __hw_addr_insert(snap, entry, addr_len);
> - snap->count++;
> + __hw_addr_count_inc(snap);
> }
>
> return 0;
> @@ -604,14 +636,14 @@ void __hw_addr_list_reconcile(struct
> netdev_hw_addr_list *real_list,
> if (delta > 0) {
> rb_erase(&ref_ha->node, &ref->tree);
> list_del(&ref_ha->list);
> - ref->count--;
> + __hw_addr_count_dec(ref);
> ref_ha->sync_cnt = delta;
> ref_ha->refcount = delta;
> list_add_tail_rcu(&ref_ha->list,
> &real_list->list);
> __hw_addr_insert(real_list, ref_ha,
> addr_len);
> - real_list->count++;
> + __hw_addr_count_inc(real_list);
> }
> continue;
> }
> @@ -622,7 +654,7 @@ void __hw_addr_list_reconcile(struct netdev_hw_addr_list
> *real_list,
> rb_erase(&real_ha->node, &real_list->tree);
> list_del_rcu(&real_ha->list);
> kfree_rcu(real_ha, rcu_head);
> - real_list->count--;
> + __hw_addr_count_dec(real_list);
> }
> }
>
> @@ -685,6 +717,7 @@ int dev_addr_init(struct net_device *dev)
> /* rtnl_mutex must be held here */
>
> __hw_addr_init(&dev->dev_addrs);
> + dev->dev_addrs.owner = dev;
> memset(addr, 0, sizeof(addr));
> err = __hw_addr_add(&dev->dev_addrs, addr, sizeof(addr),
> NETDEV_HW_ADDR_T_LAN);
> @@ -962,6 +995,7 @@ EXPORT_SYMBOL(dev_uc_flush);
> void dev_uc_init(struct net_device *dev)
> {
> __hw_addr_init(&dev->uc);
> + dev->uc.owner = dev;
> }
> EXPORT_SYMBOL(dev_uc_init);
>
> @@ -1177,6 +1211,7 @@ EXPORT_SYMBOL(dev_mc_flush);
> void dev_mc_init(struct net_device *dev)
> {
> __hw_addr_init(&dev->mc);
> + dev->mc.owner = dev;
> }
> EXPORT_SYMBOL(dev_mc_init);
>
> @@ -1348,6 +1383,7 @@ static void netif_rx_mode_retry(struct timer_list *t)
> void netif_rx_mode_init(struct net_device *dev)
> {
> __hw_addr_init(&dev->rx_mode_addr_cache);
> + dev->rx_mode_addr_cache.owner = dev;
> timer_setup(&dev->rx_mode_retry_timer, netif_rx_mode_retry, 0);
> }
>
