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Merge branch 'vlan-lockless-vlan_fill_info'

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Eric Dumazet says:

====================
vlan: lockless vlan_fill_info()

vlan_fill_info() currently relies on RTNL being held, because it
uses rcu_dereference_rtnl() to walk vlan->egress_priority_map[].

While auditing the fields exposed there, it appears that
vlan->flags, vlan->ingress_priority_map[] and vlan->nr_*_mappings
are written under RTNL but already read from lockless contexts
(RX, TX, /proc/net/vlan/<dev> and vlan_get_size()).

- Patch 1 adds the missing READ_ONCE()/WRITE_ONCE() annotations.

- Patch 2 converts vlan_fill_info() to RCU.

vlan->egress_priority_map[] needed no work: it is already updated
with rcu_assign_pointer() and freed with kfree_rcu().

This is part of a larger effort to remove the RTNL dependency from
rtnl_link_ops->fill_info().
====================

Link: https://patch.msgid.link/20260916132532.1785657-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2026-09-18 16:50:17 -07:00
commit 4090fcee93
5 changed files with 65 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/8021q/vlan.h
View File

@ -158,7 +158,7 @@ static inline u32 vlan_get_ingress_priority(struct net_device *dev,
{
struct vlan_dev_priv *vip = vlan_dev_priv(dev);
return vip->ingress_priority_map[(vlan_tci >> VLAN_PRIO_SHIFT) & 0x7];
return READ_ONCE(vip->ingress_priority_map[(vlan_tci >> VLAN_PRIO_SHIFT) & 0x7]);
}
#ifdef CONFIG_VLAN_8021Q_GVRP

2
net/8021q/vlan_core.c
View File

@ -38,7 +38,7 @@ bool vlan_do_receive(struct sk_buff **skbp)
skb->pkt_type = PACKET_HOST;
}
if (!(vlan_dev_priv(vlan_dev)->flags & VLAN_FLAG_REORDER_HDR) &&
if (!(READ_ONCE(vlan_dev_priv(vlan_dev)->flags) & VLAN_FLAG_REORDER_HDR) &&
!netif_is_macvlan_port(vlan_dev) &&
!netif_is_bridge_port(vlan_dev)) {
unsigned int offset = skb->data - skb_mac_header(skb);

37
net/8021q/vlan_dev.c
View File

@ -54,7 +54,7 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
u16 vlan_tci = 0;
int rc;
if (!(vlan->flags & VLAN_FLAG_REORDER_HDR)) {
if (!(READ_ONCE(vlan->flags) & VLAN_FLAG_REORDER_HDR)) {
vhdr = skb_push(skb, VLAN_HLEN);
vlan_tci = vlan->vlan_id;
@ -110,7 +110,7 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
* NOTE: THIS ASSUMES DIX ETHERNET, SPECIFICALLY NOT SUPPORTING
* OTHER THINGS LIKE FDDI/TokenRing/802.3 SNAPs...
*/
if (vlan->flags & VLAN_FLAG_REORDER_HDR ||
if (READ_ONCE(vlan->flags) & VLAN_FLAG_REORDER_HDR ||
veth->h_vlan_proto != vlan->vlan_proto) {
u16 vlan_tci;
vlan_tci = vlan->vlan_id;
@ -159,13 +159,16 @@ void vlan_dev_set_ingress_priority(const struct net_device *dev,
u32 skb_prio, u16 vlan_prio)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
u32 *map = &vlan->ingress_priority_map[vlan_prio & 0x7];
if (vlan->ingress_priority_map[vlan_prio & 0x7] && !skb_prio)
vlan->nr_ingress_mappings--;
else if (!vlan->ingress_priority_map[vlan_prio & 0x7] && skb_prio)
vlan->nr_ingress_mappings++;
if (*map && !skb_prio)
WRITE_ONCE(vlan->nr_ingress_mappings,
vlan->nr_ingress_mappings - 1);
else if (!*map && skb_prio)
WRITE_ONCE(vlan->nr_ingress_mappings,
vlan->nr_ingress_mappings + 1);
vlan->ingress_priority_map[vlan_prio & 0x7] = skb_prio;
WRITE_ONCE(*map, skb_prio);
}
int vlan_dev_set_egress_priority(const struct net_device *dev,
@ -185,7 +188,8 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
if (mp->priority == skb_prio) {
if (!vlan_qos) {
rcu_assign_pointer(*mpp, rtnl_dereference(mp->next));
vlan->nr_egress_mappings--;
WRITE_ONCE(vlan->nr_egress_mappings,
vlan->nr_egress_mappings - 1);
kfree_rcu(mp, rcu);
} else {
WRITE_ONCE(mp->vlan_qos, vlan_qos);
@ -209,7 +213,8 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
RCU_INIT_POINTER(np->next, rtnl_dereference(vlan->egress_priority_map[bucket]));
rcu_assign_pointer(vlan->egress_priority_map[bucket], np);
if (vlan_qos)
vlan->nr_egress_mappings++;
WRITE_ONCE(vlan->nr_egress_mappings,
vlan->nr_egress_mappings + 1);
return 0;
}
@ -220,23 +225,25 @@ int vlan_dev_change_flags(const struct net_device *dev, u32 flags, u32 mask)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
u32 old_flags = vlan->flags;
u32 new_flags;
if (mask & ~(VLAN_FLAG_REORDER_HDR | VLAN_FLAG_GVRP |
VLAN_FLAG_LOOSE_BINDING | VLAN_FLAG_MVRP |
VLAN_FLAG_BRIDGE_BINDING))
return -EINVAL;
vlan->flags = (old_flags & ~mask) | (flags & mask);
new_flags = (old_flags & ~mask) | (flags & mask);
WRITE_ONCE(vlan->flags, new_flags);
if (netif_running(dev) && (vlan->flags ^ old_flags) & VLAN_FLAG_GVRP) {
if (vlan->flags & VLAN_FLAG_GVRP)
if (netif_running(dev) && (new_flags ^ old_flags) & VLAN_FLAG_GVRP) {
if (new_flags & VLAN_FLAG_GVRP)
vlan_gvrp_request_join(dev);
else
vlan_gvrp_request_leave(dev);
}
if (netif_running(dev) && (vlan->flags ^ old_flags) & VLAN_FLAG_MVRP) {
if (vlan->flags & VLAN_FLAG_MVRP)
if (netif_running(dev) && (new_flags ^ old_flags) & VLAN_FLAG_MVRP) {
if (new_flags & VLAN_FLAG_MVRP)
vlan_mvrp_request_join(dev);
else
vlan_mvrp_request_leave(dev);
@ -599,7 +606,7 @@ void vlan_dev_free_egress_priority(const struct net_device *dev)
pm = next;
}
}
vlan->nr_egress_mappings = 0;
WRITE_ONCE(vlan->nr_egress_mappings, 0);
}
static void vlan_dev_uninit(struct net_device *dev)

52
net/8021q/vlan_netlink.c
View File

@ -209,71 +209,83 @@ static inline size_t vlan_qos_map_size(unsigned int n)
static size_t vlan_get_size(const struct net_device *dev)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
const struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
return nla_total_size(2) + /* IFLA_VLAN_PROTOCOL */
nla_total_size(2) + /* IFLA_VLAN_ID */
nla_total_size(sizeof(struct ifla_vlan_flags)) + /* IFLA_VLAN_FLAGS */
vlan_qos_map_size(vlan->nr_ingress_mappings) +
vlan_qos_map_size(vlan->nr_egress_mappings);
vlan_qos_map_size(READ_ONCE(vlan->nr_ingress_mappings)) +
vlan_qos_map_size(READ_ONCE(vlan->nr_egress_mappings));
}
static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
struct vlan_priority_tci_mapping *pm;
struct ifla_vlan_flags f;
const struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
const struct vlan_priority_tci_mapping *pm;
struct ifla_vlan_qos_mapping m;
struct ifla_vlan_flags f;
struct nlattr *nest;
unsigned int i;
u32 flags;
if (nla_put_be16(skb, IFLA_VLAN_PROTOCOL, vlan->vlan_proto) ||
nla_put_u16(skb, IFLA_VLAN_ID, vlan->vlan_id))
goto nla_put_failure;
if (vlan->flags) {
f.flags = vlan->flags;
flags = READ_ONCE(vlan->flags);
if (flags) {
f.flags = flags;
f.mask = ~0;
if (nla_put(skb, IFLA_VLAN_FLAGS, sizeof(f), &f))
goto nla_put_failure;
}
if (vlan->nr_ingress_mappings) {
rcu_read_lock();
if (READ_ONCE(vlan->nr_ingress_mappings)) {
nest = nla_nest_start_noflag(skb, IFLA_VLAN_INGRESS_QOS);
if (nest == NULL)
goto nla_put_failure;
if (!nest)
goto nla_put_failure_unlock;
for (i = 0; i < ARRAY_SIZE(vlan->ingress_priority_map); i++) {
if (!vlan->ingress_priority_map[i])
u32 skb_prio = READ_ONCE(vlan->ingress_priority_map[i]);
if (!skb_prio)
continue;
m.from = i;
m.to = vlan->ingress_priority_map[i];
m.to = skb_prio;
if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,
sizeof(m), &m))
goto nla_put_failure;
goto nla_put_failure_unlock;
}
nla_nest_end(skb, nest);
}
if (vlan->nr_egress_mappings) {
if (READ_ONCE(vlan->nr_egress_mappings)) {
nest = nla_nest_start_noflag(skb, IFLA_VLAN_EGRESS_QOS);
if (nest == NULL)
goto nla_put_failure;
if (!nest)
goto nla_put_failure_unlock;
for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
pm = rcu_dereference_rtnl(pm->next)) {
for (pm = rcu_dereference(vlan->egress_priority_map[i]); pm;
pm = rcu_dereference(pm->next)) {
u16 vlan_qos = READ_ONCE(pm->vlan_qos);
m.from = pm->priority;
m.to = (vlan_qos >> 13) & 0x7;
if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,
sizeof(m), &m))
goto nla_put_failure;
goto nla_put_failure_unlock;
}
}
nla_nest_end(skb, nest);
}
rcu_read_unlock();
return 0;
nla_put_failure_unlock:
rcu_read_unlock();
nla_put_failure:
return -EMSGSIZE;
}

18
net/8021q/vlanproc.c
View File

@ -240,7 +240,7 @@ static int vlandev_seq_show(struct seq_file *seq, void *offset)
seq_printf(seq,
"%s VID: %d REORDER_HDR: %i dev->priv_flags: %x\n",
vlandev->name, vlan->vlan_id,
(int)(vlan->flags & 1), (u32)vlandev->priv_flags);
(int)(READ_ONCE(vlan->flags) & 1), (u32)vlandev->priv_flags);
seq_printf(seq, fmt64, "total frames received", stats->rx_packets);
seq_printf(seq, fmt64, "total bytes received", stats->rx_bytes);
@ -252,14 +252,14 @@ static int vlandev_seq_show(struct seq_file *seq, void *offset)
/* now show all PRIORITY mappings relating to this VLAN */
seq_printf(seq, "\nINGRESS priority mappings: "
"0:%u 1:%u 2:%u 3:%u 4:%u 5:%u 6:%u 7:%u\n",
vlan->ingress_priority_map[0],
vlan->ingress_priority_map[1],
vlan->ingress_priority_map[2],
vlan->ingress_priority_map[3],
vlan->ingress_priority_map[4],
vlan->ingress_priority_map[5],
vlan->ingress_priority_map[6],
vlan->ingress_priority_map[7]);
READ_ONCE(vlan->ingress_priority_map[0]),
READ_ONCE(vlan->ingress_priority_map[1]),
READ_ONCE(vlan->ingress_priority_map[2]),
READ_ONCE(vlan->ingress_priority_map[3]),
READ_ONCE(vlan->ingress_priority_map[4]),
READ_ONCE(vlan->ingress_priority_map[5]),
READ_ONCE(vlan->ingress_priority_map[6]),
READ_ONCE(vlan->ingress_priority_map[7]));
seq_printf(seq, " EGRESS priority mappings: ");
rcu_read_lock();