[PATCH net-next v9 0/6] rtnetlink: dump link-layer multicast addresses

[PATCH net-next v9 0/6] rtnetlink: dump link-layer multicast addresses

[Yuyang Huang]

"ip maddr show" prints link-layer, IPv4 and IPv6 entries. The IPv4 and
IPv6 ones come over netlink today, with IFA_MC_USERS for the user count.
The link-layer list, dev->mc, is only exported via /proc/net/dev_mcast,
so iproute2 and other users still parse procfs for it.

This series adds the AF_PACKET family to RTM_GETMULTICAST so that the
link-layer multicast addresses are reported the same way. Patch 4 dumps
dev->mc in the ifaddrmsg format of the IPv4 and IPv6 dumps: IFA_MULTICAST
carries the address, IFA_MC_USERS the reference count and a new
IFA_F_GLOBAL flag marks entries added explicitly, the "static" column of
/proc/net/dev_mcast. ifa_index limits the dump to one device and
IFA_TARGET_NETNSID selects another netns. Patches 2 and 3 add a
generation counter for dev->mc changes so a multi-part dump reports
NLM_F_DUMP_INTR like the IPv4 and IPv6 ones. Patches 1 and 5 update the
rt-addr spec and patch 6 adds a selftest.

AF_PACKET dumps returned -EOPNOTSUPP before, so iproute2 can keep the
procfs fallback for older kernels. The iproute2 side is ready and will
be posted once this is in.

Changes in v9:
- Change the count of a netdev_hw_addr_list through helpers only and
  rename it to _count, as its own patch
- Use the count helpers in __hw_addr_splice() too
- Note in the spec doc that the header checks are unconditional for
  AF_PACKET only

Changes in v8:
- Set the owner of every list a device has, not only dev->mc, and
  check for dev->mc in one place when bumping the counter
- Add __hw_addr_count_inc/dec/reset() so a change of list->count and
  the counter bump stay together

Changes in v7:
- Add a per netns generation counter bumped on dev->mc changes and fold
  it into cb->seq, dev_base_seq alone did not cover the dumped entries
- Sample cb->seq under the address lock of each device and again when a
  dump round ends, so the NLMSG_DONE check sees a change too

Changes in v6:
- Move the dump to net/core/dev_addr_lists.c next to the dev->mc
  helpers
- Stamp cb->seq from dev_base_seq and check dump consistency
- Let an unexpected dump error propagate instead of skipping
- Check for an address only present in the peer netns in the
  target-netnsid selftest, the peer and local ifindex can be equal
- Document the ifa-index filter and the zero header fields in the spec

Changes in v5:
- Filter the target-netnsid selftest dump by ifa-index, a new netns
  also contains the fallback tunnel devices

Changes in v4:
- Reset the resume offset when the device the dump stopped at is gone
- Use a tracked netns reference (put_net_track)
- Say ifa-family must be set in the spec doc, drop the AF_UNSPEC remark
- Close the netlink socket and guard the checks in the selftest
- Drop the Fixes tag

Changes in v3:
- Report the static bit as a new IFA_F_GLOBAL flag in IFA_FLAGS
  instead of IFA_F_PERMANENT
- Support IFA_TARGET_NETNSID and test it
- Describe global_use accurately, it is also set by dev_mc_add_excl()
- Fix the target-netnsid type in the rt-addr spec, as its own patch

Changes in v2:
- Always validate the request header, not only with strict checking
- Use a single "with" statement in the selftest (ruff)

Yuyang Huang (6):
  netlink: specs: rt-addr: fix the type of target-netnsid
  net: change netdev_hw_addr_list count through helpers
  net: add a generation counter for dev->mc changes
  net: add AF_PACKET multicast dumps
  netlink: specs: rt-addr: document AF_PACKET multicast dumps
  selftests: net: test AF_PACKET multicast dumps

 Documentation/netlink/specs/rt-addr.yaml      |  20 +-
 .../net/ethernet/cavium/octeon/octeon_mgmt.c  |   4 +-
 .../net/wireless/microchip/wilc1000/netdev.c  |   8 +-
 include/linux/netdevice.h                     |  11 +-
 include/net/net_namespace.h                   |   1 +
 include/uapi/linux/if_addr.h                  |   1 +
 net/core/dev_addr_lists.c                     | 259 +++++++++++++++++-
 net/core/dev_addr_lists_test.c                |  18 +-
 net/core/rtnetlink.c                          |   2 +
 net/mac80211/driver-ops.h                     |   2 +-
 tools/testing/selftests/net/rtnetlink.py      |  73 ++++-
 11 files changed, 364 insertions(+), 35 deletions(-)

-- 
2.43.0

[PATCH net-next v9 1/6] netlink: specs: rt-addr: fix the type of target-netnsid

[Yuyang Huang]

The kernel parses IFA_TARGET_NETNSID as NLA_S32 and rt-link.yaml
declares its target-netnsid as s32, but rt-addr.yaml has it as binary.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
---
 Documentation/netlink/specs/rt-addr.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/rt-addr.yaml b/Documentation/netlink/specs/rt-addr.yaml
index 0ecbd24c890c6..17ead22034515 100644
--- a/Documentation/netlink/specs/rt-addr.yaml
+++ b/Documentation/netlink/specs/rt-addr.yaml
@@ -119,7 +119,7 @@ attribute-sets:
         type: u32
       -
         name: target-netnsid
-        type: binary
+        type: s32
       -
         name: proto
         type: u8
-- 
2.43.0

[PATCH net-next v9 2/6] net: change netdev_hw_addr_list count through helpers

[Yuyang Huang]

The count of a netdev_hw_addr_list is changed in several places of
dev_addr_lists.c and a few drivers read it directly. The next patch
needs to account every change of the count of dev->mc.

Add __hw_addr_count_add(), __hw_addr_count_inc(), __hw_addr_count_dec()
and __hw_addr_count_reset(), use them for every change of the count
and rename the field to _count so that a direct write stands out.
Readers keep using netdev_hw_addr_list_count() and the netdev_uc_count()
and netdev_mc_count() helpers, the few that read the field directly
are converted. No functional change.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
---
 .../net/ethernet/cavium/octeon/octeon_mgmt.c  |  4 +-
 .../net/wireless/microchip/wilc1000/netdev.c  |  8 ++--
 include/linux/netdevice.h                     |  5 ++-
 net/core/dev_addr_lists.c                     | 44 ++++++++++++++-----
 net/core/dev_addr_lists_test.c                | 18 ++++----
 net/mac80211/driver-ops.h                     |  2 +-
 6 files changed, 51 insertions(+), 30 deletions(-)

diff --git a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
index c190fc6538d4c..5e3c379b24234 100644
--- a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
+++ b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
@@ -573,14 +573,14 @@ static void octeon_mgmt_set_rx_filtering(struct net_device *netdev)
 
 	memset(&cam_state, 0, sizeof(cam_state));
 
-	if ((netdev->flags & IFF_PROMISC) || netdev->uc.count > 7) {
+	if ((netdev->flags & IFF_PROMISC) || netdev_uc_count(netdev) > 7) {
 		cam_mode = 0;
 		available_cam_entries = 8;
 	} else {
 		/* One CAM entry for the primary address, leaves seven
 		 * for the secondary addresses.
 		 */
-		available_cam_entries = 7 - netdev->uc.count;
+		available_cam_entries = 7 - netdev_uc_count(netdev);
 	}
 
 	if (netdev->flags & IFF_MULTICAST) {
diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.c b/drivers/net/wireless/microchip/wilc1000/netdev.c
index 956cb578bf37c..d3343113cea50 100644
--- a/drivers/net/wireless/microchip/wilc1000/netdev.c
+++ b/drivers/net/wireless/microchip/wilc1000/netdev.c
@@ -704,17 +704,17 @@ static void wilc_set_multicast_list(struct net_device *dev)
 		return;
 
 	if (dev->flags & IFF_ALLMULTI ||
-	    dev->mc.count > WILC_MULTICAST_TABLE_SIZE) {
+	    netdev_mc_count(dev) > WILC_MULTICAST_TABLE_SIZE) {
 		wilc_setup_multicast_filter(vif, 0, 0, NULL);
 		return;
 	}
 
-	if (dev->mc.count == 0) {
+	if (netdev_mc_empty(dev)) {
 		wilc_setup_multicast_filter(vif, 1, 0, NULL);
 		return;
 	}
 
-	mc_list = kmalloc_array(dev->mc.count, ETH_ALEN, GFP_ATOMIC);
+	mc_list = kmalloc_array(netdev_mc_count(dev), ETH_ALEN, GFP_ATOMIC);
 	if (!mc_list)
 		return;
 
@@ -727,7 +727,7 @@ static void wilc_set_multicast_list(struct net_device *dev)
 		cur_mc += ETH_ALEN;
 	}
 
-	if (wilc_setup_multicast_filter(vif, 1, dev->mc.count, mc_list))
+	if (wilc_setup_multicast_filter(vif, 1, netdev_mc_count(dev), mc_list))
 		kfree(mc_list);
 }
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d037faff7c44b..97dc053f234cc 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -252,13 +252,14 @@ struct netdev_hw_addr {
 
 struct netdev_hw_addr_list {
 	struct list_head	list;
-	int			count;
+	/* Only changed through the __hw_addr_count_* helpers */
+	int			_count;
 
 	/* Auxiliary tree for faster lookup on addition and deletion */
 	struct rb_root		tree;
 };
 
-#define netdev_hw_addr_list_count(l) ((l)->count)
+#define netdev_hw_addr_list_count(l) ((l)->_count)
 #define netdev_hw_addr_list_empty(l) (netdev_hw_addr_list_count(l) == 0)
 #define netdev_hw_addr_list_for_each(ha, l) \
 	list_for_each_entry(ha, &(l)->list, list)
diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
index 08528ca0a8b31..23f5db99a702d 100644
--- a/net/core/dev_addr_lists.c
+++ b/net/core/dev_addr_lists.c
@@ -16,6 +16,26 @@
 
 #include "dev.h"
 
+static void __hw_addr_count_add(struct netdev_hw_addr_list *list, int value)
+{
+	list->_count += value;
+}
+
+static void __hw_addr_count_inc(struct netdev_hw_addr_list *list)
+{
+	__hw_addr_count_add(list, 1);
+}
+
+static void __hw_addr_count_dec(struct netdev_hw_addr_list *list)
+{
+	__hw_addr_count_add(list, -1);
+}
+
+static void __hw_addr_count_reset(struct netdev_hw_addr_list *list)
+{
+	list->_count = 0;
+}
+
 /*
  * General list handling functions
  */
@@ -125,7 +145,7 @@ 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 +181,7 @@ 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;
 }
 
@@ -492,14 +512,14 @@ 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);
 
 void __hw_addr_init(struct netdev_hw_addr_list *list)
 {
 	INIT_LIST_HEAD(&list->list);
-	list->count = 0;
+	list->_count = 0;
 	list->tree = RB_ROOT;
 }
 EXPORT_SYMBOL(__hw_addr_init);
@@ -509,8 +529,8 @@ 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);
 }
 
 /**
@@ -532,11 +552,11 @@ int __hw_addr_list_snapshot(struct netdev_hw_addr_list *snap,
 	struct netdev_hw_addr *ha, *entry;
 
 	list_for_each_entry(ha, &list->list, list) {
-		if (cache->count) {
+		if (cache->_count) {
 			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 +574,7 @@ 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 +624,14 @@ 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 +642,7 @@ 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);
 		}
 	}
 
diff --git a/net/core/dev_addr_lists_test.c b/net/core/dev_addr_lists_test.c
index 260e71a2399f3..07c35a0af2b4d 100644
--- a/net/core/dev_addr_lists_test.c
+++ b/net/core/dev_addr_lists_test.c
@@ -291,7 +291,7 @@ static void dev_addr_test_snapshot_sync(struct kunit *test)
 	netif_addr_unlock_bh(netdev);
 
 	/* Real entry should now reflect the sync: sync_cnt=1, refcount=2 */
-	KUNIT_EXPECT_EQ(test, 1, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 1, netdev_uc_count(netdev));
 	ha = list_first_entry(&netdev->uc.list, struct netdev_hw_addr, list);
 	KUNIT_EXPECT_MEMEQ(test, ha->addr, addr, ETH_ALEN);
 	KUNIT_EXPECT_EQ(test, 1, ha->sync_cnt);
@@ -303,7 +303,7 @@ static void dev_addr_test_snapshot_sync(struct kunit *test)
 			   dev_addr_test_unsync);
 	KUNIT_EXPECT_EQ(test, 0, datp->addr_synced);
 	KUNIT_EXPECT_EQ(test, 0, datp->addr_unsynced);
-	KUNIT_EXPECT_EQ(test, 1, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 1, netdev_uc_count(netdev));
 
 	__hw_addr_flush(&cache);
 	rtnl_unlock();
@@ -351,7 +351,7 @@ static void dev_addr_test_snapshot_remove_during_sync(struct kunit *test)
 	/* Concurrent removal: user deletes ADDR_A while driver was working */
 	memset(addr, ADDR_A, sizeof(addr));
 	KUNIT_EXPECT_EQ(test, 0, dev_uc_del(netdev, addr));
-	KUNIT_EXPECT_EQ(test, 0, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 0, netdev_uc_count(netdev));
 
 	/* Reconcile: ADDR_A gone from real list but driver synced it,
 	 * so it gets re-inserted as stale (sync_cnt=1, refcount=1).
@@ -361,7 +361,7 @@ static void dev_addr_test_snapshot_remove_during_sync(struct kunit *test)
 				 &cache);
 	netif_addr_unlock_bh(netdev);
 
-	KUNIT_EXPECT_EQ(test, 1, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 1, netdev_uc_count(netdev));
 	ha = list_first_entry(&netdev->uc.list, struct netdev_hw_addr, list);
 	KUNIT_EXPECT_MEMEQ(test, ha->addr, addr, ETH_ALEN);
 	KUNIT_EXPECT_EQ(test, 1, ha->sync_cnt);
@@ -373,7 +373,7 @@ static void dev_addr_test_snapshot_remove_during_sync(struct kunit *test)
 			   dev_addr_test_unsync);
 	KUNIT_EXPECT_EQ(test, 0, datp->addr_synced);
 	KUNIT_EXPECT_EQ(test, 1 << ADDR_A, datp->addr_unsynced);
-	KUNIT_EXPECT_EQ(test, 0, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 0, netdev_uc_count(netdev));
 
 	__hw_addr_flush(&cache);
 	rtnl_unlock();
@@ -433,7 +433,7 @@ static void dev_addr_test_snapshot_readd_during_unsync(struct kunit *test)
 	 * stale entry and bumps refcount from 1 -> 2.  sync_cnt stays 1.
 	 */
 	KUNIT_EXPECT_EQ(test, 0, dev_uc_add(netdev, addr));
-	KUNIT_EXPECT_EQ(test, 1, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 1, netdev_uc_count(netdev));
 
 	/* Reconcile: ref sync_cnt=1 matches real sync_cnt=1, delta=-1
 	 * applied. Result: sync_cnt=0, refcount=1 (fresh).
@@ -444,7 +444,7 @@ static void dev_addr_test_snapshot_readd_during_unsync(struct kunit *test)
 	netif_addr_unlock_bh(netdev);
 
 	/* Entry survives as fresh: needs re-sync to HW */
-	KUNIT_EXPECT_EQ(test, 1, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 1, netdev_uc_count(netdev));
 	ha = list_first_entry(&netdev->uc.list, struct netdev_hw_addr, list);
 	KUNIT_EXPECT_MEMEQ(test, ha->addr, addr, ETH_ALEN);
 	KUNIT_EXPECT_EQ(test, 0, ha->sync_cnt);
@@ -528,7 +528,7 @@ static void dev_addr_test_snapshot_add_and_remove(struct kunit *test)
 	 * ADDR_B: refcount went from 2->1 via dev_uc_del (still present, stale)
 	 * ADDR_C: sync propagated (sync_cnt=1, refcount=2)
 	 */
-	KUNIT_EXPECT_EQ(test, 3, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 3, netdev_uc_count(netdev));
 	netdev_hw_addr_list_for_each(ha, &netdev->uc) {
 		u8 id = ha->addr[0];
 
@@ -553,7 +553,7 @@ static void dev_addr_test_snapshot_add_and_remove(struct kunit *test)
 			   dev_addr_test_unsync);
 	KUNIT_EXPECT_EQ(test, 0, datp->addr_synced);
 	KUNIT_EXPECT_EQ(test, 1 << ADDR_B, datp->addr_unsynced);
-	KUNIT_EXPECT_EQ(test, 2, netdev->uc.count);
+	KUNIT_EXPECT_EQ(test, 2, netdev_uc_count(netdev));
 
 	__hw_addr_flush(&cache);
 	rtnl_unlock();
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index f1c0b87fddd5f..e80731c59ef50 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -187,7 +187,7 @@ static inline u64 drv_prepare_multicast(struct ieee80211_local *local,
 {
 	u64 ret = 0;
 
-	trace_drv_prepare_multicast(local, mc_list->count);
+	trace_drv_prepare_multicast(local, netdev_hw_addr_list_count(mc_list));
 
 	if (local->ops->prepare_multicast)
 		ret = local->ops->prepare_multicast(&local->hw, mc_list);
-- 
2.43.0

[PATCH net-next v9 3/6] net: add a generation counter for dev->mc changes

[Yuyang Huang]

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 bump the counter of
dev_net(owner) from the count helpers 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 <sigefriedhyy@gmail.com>
---
 include/linux/netdevice.h   |  5 +++++
 include/net/net_namespace.h |  1 +
 net/core/dev_addr_lists.c   | 20 ++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 97dc053f234cc..d409c56a02459 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -257,6 +257,11 @@ 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 46b4c67e2966f..d8c681ab5c749 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 23f5db99a702d..783c62895249b 100644
--- a/net/core/dev_addr_lists.c
+++ b/net/core/dev_addr_lists.c
@@ -16,9 +16,21 @@
 
 #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_add(struct netdev_hw_addr_list *list, int value)
 {
 	list->_count += value;
+	__hw_addr_changed(list);
 }
 
 static void __hw_addr_count_inc(struct netdev_hw_addr_list *list)
@@ -33,7 +45,10 @@ static void __hw_addr_count_dec(struct netdev_hw_addr_list *list)
 
 static void __hw_addr_count_reset(struct netdev_hw_addr_list *list)
 {
+	if (!list->_count)
+		return;
 	list->_count = 0;
+	__hw_addr_changed(list);
 }
 
 /*
@@ -521,6 +536,7 @@ 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);
 
@@ -705,6 +721,7 @@ 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);
@@ -982,6 +999,7 @@ 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);
 
@@ -1197,6 +1215,7 @@ 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);
 
@@ -1368,6 +1387,7 @@ 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);
 }
 
-- 
2.43.0

[PATCH net-next v9 4/6] net: add AF_PACKET multicast dumps

[Yuyang Huang]

RTM_GETMULTICAST dumps IPv4 and IPv6 multicast group memberships, but
the device multicast list (dev->mc) is only available through
/proc/net/dev_mcast, so "ip maddr show" still has to parse procfs for
its link-layer entries.

Handle RTM_GETMULTICAST dumps with ifa_family set to AF_PACKET next to
the dev->mc helpers in dev_addr_lists.c and report every entry of
dev->mc in the existing ifaddrmsg format:

  - IFA_MULTICAST carries the raw link-layer address
  - IFA_MC_USERS carries the entry reference count
  - IFA_F_GLOBAL in IFA_FLAGS reports netdev_hw_addr::global_use, set
    by dev_mc_add_global() (SIOCADDMULTI) and dev_mc_add_excl()
    ("bridge fdb add ... self"), i.e. entries added explicitly rather
    than by a protocol join. This is the static column of
    /proc/net/dev_mcast
  - ifa_scope is RT_SCOPE_LINK

This covers every column of /proc/net/dev_mcast. AF_PACKET is the
family iproute2 already uses for link-layer addresses ("ip -0").

The default FDB dump also walks dev->mc, but only for Ethernet devices
without an ndo_fdb_dump of their own, so bridge, vxlan or macvlan
devices never show their multicast filter there, and it has no users
count or global_use bit. Extending it would change "bridge fdb show"
output and add NDA_* attributes.

Requests are always validated, there are no legacy users: prefixlen,
flags and scope must be zero, ifa_index selects one device and
IFA_TARGET_NETNSID is the only attribute accepted. The dump runs under
RCU and netif_addr_lock_bh() without RTNL. cb->seq is sampled from the
dev->mc generation counter and dev_base_seq under the address lock of
each device and again when a round ends, so a change since the previous
device or dump round sets NLM_F_DUMP_INTR, also when the last round
dumps nothing because the device it stopped at is gone.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
 include/linux/netdevice.h    |   1 +
 include/uapi/linux/if_addr.h |   1 +
 net/core/dev_addr_lists.c    | 195 +++++++++++++++++++++++++++++++++++
 net/core/rtnetlink.c         |   2 +
 4 files changed, 199 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d409c56a02459..6eabaa0b48e0c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -5168,6 +5168,7 @@ int dev_mc_sync_multiple(struct net_device *to, struct net_device *from);
 void dev_mc_unsync(struct net_device *to, struct net_device *from);
 void dev_mc_flush(struct net_device *dev);
 void dev_mc_init(struct net_device *dev);
+int dev_mc_dump(struct sk_buff *skb, struct netlink_callback *cb);
 
 /**
  *  __dev_mc_sync - Synchronize device's multicast list
diff --git a/include/uapi/linux/if_addr.h b/include/uapi/linux/if_addr.h
index 7fb630b7fe311..0a1ad9ebb47be 100644
--- a/include/uapi/linux/if_addr.h
+++ b/include/uapi/linux/if_addr.h
@@ -57,6 +57,7 @@ enum {
 #define IFA_F_NOPREFIXROUTE	0x200
 #define IFA_F_MCAUTOJOIN	0x400
 #define IFA_F_STABLE_PRIVACY	0x800
+#define IFA_F_GLOBAL		0x1000
 
 struct ifa_cacheinfo {
 	__u32	ifa_prefered;
diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
index 783c62895249b..948dc25635938 100644
--- a/net/core/dev_addr_lists.c
+++ b/net/core/dev_addr_lists.c
@@ -10,8 +10,12 @@
 #include <linux/netdevice.h>
 #include <linux/rtnetlink.h>
 #include <linux/export.h>
+#include <linux/if_addr.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
+#include <net/netlink.h>
+#include <net/rtnetlink.h>
+#include <net/sock.h>
 #include <kunit/visibility.h>
 
 #include "dev.h"
@@ -1219,6 +1223,197 @@ void dev_mc_init(struct net_device *dev)
 }
 EXPORT_SYMBOL(dev_mc_init);
 
+static int dev_mc_fill_addr(struct sk_buff *skb, const struct net_device *dev,
+			    const struct netdev_hw_addr *ha, u32 portid,
+			    u32 seq, unsigned int flags, int netnsid)
+{
+	u32 ifa_flags = ha->global_use ? IFA_F_GLOBAL : 0;
+	struct ifaddrmsg *ifm;
+	struct nlmsghdr *nlh;
+
+	nlh = nlmsg_put(skb, portid, seq, RTM_GETMULTICAST, sizeof(*ifm),
+			flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	ifm = nlmsg_data(nlh);
+	ifm->ifa_family = AF_PACKET;
+	ifm->ifa_prefixlen = 0;
+	/* ifm->ifa_flags holds 8 bits, the full value is in IFA_FLAGS */
+	ifm->ifa_flags = (__u8)ifa_flags;
+	ifm->ifa_scope = RT_SCOPE_LINK;
+	ifm->ifa_index = dev->ifindex;
+
+	if ((netnsid >= 0 &&
+	     nla_put_s32(skb, IFA_TARGET_NETNSID, netnsid)) ||
+	    nla_put(skb, IFA_MULTICAST, dev->addr_len, ha->addr) ||
+	    nla_put_u32(skb, IFA_MC_USERS, ha->refcount) ||
+	    nla_put_u32(skb, IFA_FLAGS, ifa_flags)) {
+		nlmsg_cancel(skb, nlh);
+		return -EMSGSIZE;
+	}
+
+	nlmsg_end(skb, nlh);
+	return 0;
+}
+
+/* Combine dev_mc_genid and dev_base_seq to detect changes, like
+ * inet_base_seq().
+ */
+static u32 dev_mc_base_seq(const struct net *net)
+{
+	u32 res = atomic_read(&net->dev_mc_genid) +
+		  READ_ONCE(net->dev_base_seq);
+
+	/* Must not return 0 (see nl_dump_check_consistent()). */
+	if (!res)
+		res = 0x80000000;
+	return res;
+}
+
+static int dev_mc_dump_dev(struct net_device *dev, struct sk_buff *skb,
+			   struct netlink_callback *cb, int *s_addr_idx,
+			   unsigned int flags, int netnsid)
+{
+	struct netdev_hw_addr *ha;
+	int addr_idx = 0;
+	int err = 0;
+
+	netif_addr_lock_bh(dev);
+	/* Sampled under the lock, see nl_dump_check_consistent() */
+	cb->seq = dev_mc_base_seq(dev_net(dev));
+	netdev_for_each_mc_addr(ha, dev) {
+		if (addr_idx < *s_addr_idx) {
+			addr_idx++;
+			continue;
+		}
+		err = dev_mc_fill_addr(skb, dev, ha, NETLINK_CB(cb->skb).portid,
+				       cb->nlh->nlmsg_seq, flags, netnsid);
+		if (err < 0)
+			break;
+		nl_dump_check_consistent(cb, nlmsg_hdr(skb));
+		addr_idx++;
+	}
+	netif_addr_unlock_bh(dev);
+
+	*s_addr_idx = err < 0 ? addr_idx : 0;
+
+	return err;
+}
+
+struct dev_mc_dump_filter {
+	struct net *tgt_net;
+	netns_tracker ns_tracker;
+	int netnsid;
+	int ifindex;
+};
+
+static const struct nla_policy dev_mc_dump_policy[IFA_MAX + 1] = {
+	[IFA_TARGET_NETNSID]	= { .type = NLA_S32 },
+};
+
+static int dev_mc_valid_dump_req(const struct nlmsghdr *nlh, struct sock *sk,
+				 struct dev_mc_dump_filter *filter,
+				 struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[IFA_MAX + 1];
+	struct ifaddrmsg *ifm;
+	int err;
+
+	ifm = nlmsg_payload(nlh, sizeof(*ifm));
+	if (!ifm) {
+		NL_SET_ERR_MSG(extack,
+			       "Invalid header for multicast dump request");
+		return -EINVAL;
+	}
+
+	if (ifm->ifa_prefixlen || ifm->ifa_flags || ifm->ifa_scope) {
+		NL_SET_ERR_MSG(extack,
+			       "Invalid values in multicast dump header");
+		return -EINVAL;
+	}
+
+	err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX,
+			  dev_mc_dump_policy, extack);
+	if (err < 0)
+		return err;
+
+	if (tb[IFA_TARGET_NETNSID]) {
+		struct net *net;
+
+		filter->netnsid = nla_get_s32(tb[IFA_TARGET_NETNSID]);
+		net = rtnl_get_net_ns_capable(sk, filter->netnsid);
+		if (IS_ERR(net)) {
+			NL_SET_ERR_MSG(extack,
+				       "Invalid target network namespace id");
+			return PTR_ERR(net);
+		}
+		netns_tracker_alloc(net, &filter->ns_tracker, GFP_KERNEL);
+		filter->tgt_net = net;
+	}
+
+	filter->ifindex = ifm->ifa_index;
+
+	return 0;
+}
+
+int dev_mc_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct dev_mc_dump_filter filter = {
+		.tgt_net = sock_net(skb->sk),
+		.netnsid = -1,
+	};
+	unsigned int flags = NLM_F_MULTI;
+	struct {
+		unsigned long ifindex;
+		int addr_idx;
+	} *ctx = (void *)cb->ctx;
+	unsigned long s_ifindex;
+	struct net_device *dev;
+	int err;
+
+	err = dev_mc_valid_dump_req(cb->nlh, skb->sk, &filter, cb->extack);
+	if (err < 0)
+		return err;
+
+	rcu_read_lock();
+
+	if (filter.ifindex) {
+		cb->answer_flags |= NLM_F_DUMP_FILTERED;
+		flags |= NLM_F_DUMP_FILTERED;
+		dev = dev_get_by_index_rcu(filter.tgt_net, filter.ifindex);
+		if (!dev) {
+			err = -ENODEV;
+			goto out;
+		}
+		err = dev_mc_dump_dev(dev, skb, cb, &ctx->addr_idx, flags,
+				      filter.netnsid);
+		goto out;
+	}
+
+	s_ifindex = ctx->ifindex;
+	for_each_netdev_dump(filter.tgt_net, dev, ctx->ifindex) {
+		/* The device the dump stopped at is gone, do not skip
+		 * entries of the next one.
+		 */
+		if (dev->ifindex != s_ifindex)
+			ctx->addr_idx = 0;
+		err = dev_mc_dump_dev(dev, skb, cb, &ctx->addr_idx, flags,
+				      filter.netnsid);
+		if (err < 0)
+			break;
+	}
+out:
+	/* A round that dumps no device, e.g. the one it stopped at is gone,
+	 * still needs the NLMSG_DONE check to see the change.
+	 */
+	cb->seq = dev_mc_base_seq(filter.tgt_net);
+	rcu_read_unlock();
+	if (filter.netnsid >= 0)
+		put_net_track(filter.tgt_net, &filter.ns_tracker);
+	return err;
+}
+
 static int netif_addr_lists_snapshot(struct net_device *dev,
 				     struct netdev_hw_addr_list *uc_snap,
 				     struct netdev_hw_addr_list *mc_snap,
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index e3444fd240615..204dc9040e3cc 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -7278,6 +7278,8 @@ static const struct rtnl_msg_handler rtnetlink_rtnl_msg_handlers[] __initconst =
 	{.msgtype = RTM_SETSTATS, .doit = rtnl_stats_set},
 	{.msgtype = RTM_NEWLINKPROP, .doit = rtnl_newlinkprop},
 	{.msgtype = RTM_DELLINKPROP, .doit = rtnl_dellinkprop},
+	{.protocol = PF_PACKET, .msgtype = RTM_GETMULTICAST,
+	 .dumpit = dev_mc_dump, .flags = RTNL_FLAG_DUMP_UNLOCKED},
 	{.protocol = PF_BRIDGE, .msgtype = RTM_GETLINK,
 	 .dumpit = rtnl_bridge_getlink},
 	{.protocol = PF_BRIDGE, .msgtype = RTM_DELLINK,
-- 
2.43.0

[PATCH net-next v9 5/6] netlink: specs: rt-addr: document AF_PACKET multicast dumps

[Yuyang Huang]

Add the global flag, list the attributes the AF_PACKET dump uses and
describe how ifa-family selects IPv4, IPv6 or link-layer output for
RTM_GETMULTICAST.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
 Documentation/netlink/specs/rt-addr.yaml | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/Documentation/netlink/specs/rt-addr.yaml b/Documentation/netlink/specs/rt-addr.yaml
index 17ead22034515..1bd1184d1e202 100644
--- a/Documentation/netlink/specs/rt-addr.yaml
+++ b/Documentation/netlink/specs/rt-addr.yaml
@@ -77,6 +77,8 @@ definitions:
         name: mcautojoin
       -
         name: stable-privacy
+      -
+        name: global
 
 attribute-sets:
   -
@@ -168,7 +170,16 @@ operations:
           attributes: *ifaddr-all
     -
       name: getmulticast
-      doc: Get / dump IPv4/IPv6 multicast addresses.
+      doc: |
+        Get / dump multicast addresses. ifa-family must select the address
+        family: AF_INET or AF_INET6 for the IP multicast groups joined on
+        a device, AF_PACKET for the link-layer multicast addresses in the
+        device filter. Link-layer entries added explicitly, e.g. with
+        SIOCADDMULTI or "bridge fdb add ... self", rather than by a
+        protocol join are reported with the global flag set. For AF_PACKET
+        a non-zero ifa-index restricts the dump to that device and
+        ifa-prefixlen, ifa-flags and ifa-scope must be zero, AF_INET and
+        AF_INET6 apply this with NETLINK_GET_STRICT_CHK only.
       attribute-set: addr-attrs
       fixed-header: ifaddrmsg
       do:
@@ -181,10 +192,13 @@ operations:
             - multicast
             - mc-users
             - cacheinfo
+            - flags
+            - target-netnsid
       dump:
         request:
           value: 58
-          attributes: []
+          attributes:
+            - target-netnsid
         reply:
           value: 58
           attributes: *mcaddr-attrs
-- 
2.43.0

[PATCH net-next v9 6/6] selftests: net: test AF_PACKET multicast dumps

[Yuyang Huang]

Dump the link-layer multicast addresses of a dummy device and verify
that ifa_index restricts the dump to that device, that the all-hosts
address joined on link up is listed without IFA_F_GLOBAL, that an
address added with SIOCADDMULTI is listed with IFA_F_GLOBAL and
IFA_MC_USERS, and that IFA_TARGET_NETNSID dumps another netns.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
 tools/testing/selftests/net/rtnetlink.py | 73 +++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/rtnetlink.py b/tools/testing/selftests/net/rtnetlink.py
index dc8c77db48974..5534ade056a5c 100755
--- a/tools/testing/selftests/net/rtnetlink.py
+++ b/tools/testing/selftests/net/rtnetlink.py
@@ -5,13 +5,18 @@ import socket
 import struct
 import time
 from lib.py import bkg, ip, ksft_exit, ksft_run, ksft_eq, ksft_ge, ksft_true, KsftSkipEx
-from lib.py import ksft_not_in, ksft_not_none
+from lib.py import ksft_in, ksft_not_in, ksft_not_none
 from lib.py import CmdExitFailure, NetNS, NetNSEnter, RtnlAddrFamily, RtnlRouteFamily
 from lib.py import defer
 
 IPV4_ALL_HOSTS_MULTICAST = b'\xe0\x00\x00\x01'
 IPV4_TEST_MULTICAST = b'\xef\x01\x01\x01'
 IPV6_TEST_MULTICAST = bytes.fromhex('ff020000000000000000000000000123')
+ETH_ALL_HOSTS_MULTICAST = bytes.fromhex('01005e000001')
+ETH_TEST_MULTICAST_STR = '01:00:5e:01:01:01'
+ETH_TEST_MULTICAST = bytes.fromhex(ETH_TEST_MULTICAST_STR.replace(':', ''))
+ETH_PEER_MULTICAST_STR = '01:00:5e:02:02:02'
+ETH_PEER_MULTICAST = bytes.fromhex(ETH_PEER_MULTICAST_STR.replace(':', ''))
 
 
 def _users_for(rtnl: RtnlAddrFamily, family: int, grp: bytes, ifindex: int):
@@ -105,6 +110,69 @@ def dump_mcaddr6_check() -> None:
                 s2.close()
 
 
+def dump_mcaddr_l2_check() -> None:
+    """
+    Verify link-layer multicast addresses in an AF_PACKET RTM_GETMULTICAST
+    dump: the ifa-index filter, mc-users, the global flag and
+    target-netnsid.
+    """
+
+    with NetNS() as ns, NetNSEnter(str(ns)):
+        for ifname in ("dummy1", "dummy2"):
+            ip(f"link add name {ifname} type dummy")
+            ip(f"link set {ifname} up")
+        dev_idx = socket.if_nametoindex("dummy1")
+        ip(f"maddr add {ETH_TEST_MULTICAST_STR} dev dummy1")
+
+        rtnl = RtnlAddrFamily()
+        defer(rtnl.close)
+        addresses = rtnl.getmulticast(
+            {"ifa-family": socket.AF_PACKET, "ifa-index": dev_idx},
+            dump=True)
+
+        # dummy2 has entries as well, only dummy1 may be listed
+        ksft_eq({addr['ifa-index'] for addr in addresses}, {dev_idx},
+                "AF_PACKET multicast dump ignored ifa-index filter")
+
+        entries = {addr['multicast']: addr for addr in addresses}
+
+        # Bringing an Ethernet device up joins 224.0.0.1, which maps
+        # to 01:00:5e:00:00:01 in the device multicast list.
+        all_hosts = entries.get(ETH_ALL_HOSTS_MULTICAST)
+        ksft_not_none(all_hosts,
+                      "dummy1 does not have the all-hosts link-layer address")
+        if all_hosts is not None:
+            ksft_not_in('global', all_hosts['flags'],
+                        "protocol entry is global")
+
+        static = entries.get(ETH_TEST_MULTICAST)
+        ksft_not_none(static, "dummy1 does not have the SIOCADDMULTI address")
+        if static is not None:
+            ksft_eq(static['mc-users'], 1,
+                    "unexpected mc-users for the SIOCADDMULTI address")
+            ksft_in('global', static['flags'],
+                    "SIOCADDMULTI entry is not global")
+
+        # target-netnsid dumps another netns, ifa-index is relative to it
+        with NetNS() as peer:
+            ip(f"netns set {peer} 5")
+            ip("link add name dummy3 type dummy", ns=peer)
+            ip("link set dummy3 up", ns=peer)
+            ip(f"maddr add {ETH_PEER_MULTICAST_STR} dev dummy3", ns=peer)
+            peer_idx = ip("link show dummy3", json=True, ns=peer)[0]['ifindex']
+
+            addresses = rtnl.getmulticast(
+                {"ifa-family": socket.AF_PACKET, "target-netnsid": 5,
+                 "ifa-index": peer_idx}, dump=True)
+            ksft_eq({(addr['ifa-index'], addr['target-netnsid'])
+                     for addr in addresses}, {(peer_idx, 5)},
+                    "target-netnsid did not dump the peer netns")
+            # dummy1 in this netns can have the same ifindex as dummy3
+            ksft_in(ETH_PEER_MULTICAST,
+                    {addr['multicast'] for addr in addresses},
+                    "target-netnsid did not dump the peer device")
+
+
 def ipv4_devconf_notify() -> None:
     """
     Configure an interface and set ipv4-devconf values through netlink
@@ -424,7 +492,8 @@ def ipv6_verify_inter_scope_addr_order() -> None:
 
 
 def main() -> None:
-    ksft_run([dump_mcaddr_check, dump_mcaddr6_check, ipv4_devconf_notify,
+    ksft_run([dump_mcaddr_check, dump_mcaddr6_check, dump_mcaddr_l2_check,
+              ipv4_devconf_notify,
               ipv6_route_del_reason_expired,
               ipv6_route_del_reason_ra_withdrawn,
               ipv6_route_del_reason_absent,
-- 
2.43.0

Re: [PATCH net-next v9 2/6] net: change netdev_hw_addr_list count through helpers

[Nicolas Dichtel]

Le 30/09/2026 à 13:28, Yuyang Huang a écrit :
> The count of a netdev_hw_addr_list is changed in several places of
> dev_addr_lists.c and a few drivers read it directly. The next patch
> needs to account every change of the count of dev->mc.
> 
> Add __hw_addr_count_add(), __hw_addr_count_inc(), __hw_addr_count_dec()
> and __hw_addr_count_reset(), use them for every change of the count
> and rename the field to _count so that a direct write stands out.
> Readers keep using netdev_hw_addr_list_count() and the netdev_uc_count()
> and netdev_mc_count() helpers, the few that read the field directly
> are converted. No functional change.
> 
> Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

If you respin a version, you can use netdev_hw_addr_list_count() in
__hw_addr_list_snapshot() also.

Thanks,
Nicolas

Re: [PATCH net-next v9 3/6] net: add a generation counter for dev->mc changes

[Nicolas Dichtel]

Le 30/09/2026 à 13:28, 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 bump the counter of
> dev_net(owner) from the count helpers 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 <sigefriedhyy@gmail.com>

Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

Re: [PATCH net-next v9 2/6] net: change netdev_hw_addr_list count through helpers

[Yuyang Huang]

> If you respin a version, you can use netdev_hw_addr_list_count() in
> __hw_addr_list_snapshot() also.

Thanks, will do if there is a v10.

On Wed, Sep 30, 2026 at 10:03 PM Nicolas Dichtel
<nicolas.dichtel@6wind.com> wrote:
>
> Le 30/09/2026 à 13:28, Yuyang Huang a écrit :
> > The count of a netdev_hw_addr_list is changed in several places of
> > dev_addr_lists.c and a few drivers read it directly. The next patch
> > needs to account every change of the count of dev->mc.
> >
> > Add __hw_addr_count_add(), __hw_addr_count_inc(), __hw_addr_count_dec()
> > and __hw_addr_count_reset(), use them for every change of the count
> > and rename the field to _count so that a direct write stands out.
> > Readers keep using netdev_hw_addr_list_count() and the netdev_uc_count()
> > and netdev_mc_count() helpers, the few that read the field directly
> > are converted. No functional change.
> >
> > Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
> Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
>
> If you respin a version, you can use netdev_hw_addr_list_count() in
> __hw_addr_list_snapshot() also.
>
> Thanks,
> Nicolas

Re: [PATCH net-next v9 2/6] net: change netdev_hw_addr_list count through helpers

[Nicolas Dichtel]

Le 30/09/2026 à 15:43, Yuyang Huang a écrit :
>> If you respin a version, you can use netdev_hw_addr_list_count() in
>> __hw_addr_list_snapshot() also.
> 
> Thanks, will do if there is a v10.
Thanks. FYI, please don't top post:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst#n336

Re: [PATCH net-next v9 2/6] net: change netdev_hw_addr_list count through helpers

[Yuyang Huang]

> Thanks. FYI, please don't top post:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst#n336

Thanks for the reminder, will be more careful next time.