From: Longxuan Yu Date: Mon, 20 Apr 2026 03:18:45 +0000 (+0800) Subject: 8021q: use RCU for egress QoS mappings X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fc69decc811b155a0ed8eef17ee940f28c4f6dbc;p=thirdparty%2Fkernel%2Fstable.git 8021q: use RCU for egress QoS mappings The TX fast path and reporting paths walk egress QoS mappings without RTNL. Convert the mapping lists to RCU-protected pointers, use RCU reader annotations in readers, and defer freeing mapping nodes with an embedded rcu_head. This prepares the egress QoS mapping code for safe removal of mapping nodes in a follow-up change while preserving the current behavior. Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Signed-off-by: Longxuan Yu Signed-off-by: Ren Wei Link: https://patch.msgid.link/9136768189f8c6d3f824f476c62d2fa1111688e8.1776647968.git.yuantan098@gmail.com Signed-off-by: Paolo Abeni --- diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index e6272f9c5e42c..20cc16ea4e5ab 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -147,11 +147,13 @@ extern __be16 vlan_dev_vlan_proto(const struct net_device *dev); * @priority: skb priority * @vlan_qos: vlan priority: (skb->priority << 13) & 0xE000 * @next: pointer to next struct + * @rcu: used for deferred freeing of mapping nodes */ struct vlan_priority_tci_mapping { u32 priority; u16 vlan_qos; - struct vlan_priority_tci_mapping *next; + struct vlan_priority_tci_mapping __rcu *next; + struct rcu_head rcu; }; struct proc_dir_entry; @@ -177,7 +179,7 @@ struct vlan_dev_priv { unsigned int nr_ingress_mappings; u32 ingress_priority_map[8]; unsigned int nr_egress_mappings; - struct vlan_priority_tci_mapping *egress_priority_map[16]; + struct vlan_priority_tci_mapping __rcu *egress_priority_map[16]; __be16 vlan_proto; u16 vlan_id; @@ -209,19 +211,24 @@ static inline u16 vlan_dev_get_egress_qos_mask(struct net_device *dev, u32 skprio) { struct vlan_priority_tci_mapping *mp; + u16 vlan_qos = 0; - smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */ + rcu_read_lock(); - mp = vlan_dev_priv(dev)->egress_priority_map[(skprio & 0xF)]; + mp = rcu_dereference(vlan_dev_priv(dev)->egress_priority_map[skprio & 0xF]); while (mp) { if (mp->priority == skprio) { - return mp->vlan_qos; /* This should already be shifted - * to mask correctly with the - * VLAN's TCI */ + vlan_qos = READ_ONCE(mp->vlan_qos); + break; } - mp = mp->next; + mp = rcu_dereference(mp->next); } - return 0; + rcu_read_unlock(); + + /* This should already be shifted to mask correctly with + * the VLAN's TCI. + */ + return vlan_qos; } extern bool vlan_do_receive(struct sk_buff **skb); diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index c40f7d5c4fca5..a5340932b657a 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -172,39 +172,34 @@ int vlan_dev_set_egress_priority(const struct net_device *dev, u32 skb_prio, u16 vlan_prio) { struct vlan_dev_priv *vlan = vlan_dev_priv(dev); - struct vlan_priority_tci_mapping *mp = NULL; + struct vlan_priority_tci_mapping *mp; struct vlan_priority_tci_mapping *np; + u32 bucket = skb_prio & 0xF; u32 vlan_qos = (vlan_prio << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK; /* See if a priority mapping exists.. */ - mp = vlan->egress_priority_map[skb_prio & 0xF]; + mp = rtnl_dereference(vlan->egress_priority_map[bucket]); while (mp) { if (mp->priority == skb_prio) { if (mp->vlan_qos && !vlan_qos) vlan->nr_egress_mappings--; else if (!mp->vlan_qos && vlan_qos) vlan->nr_egress_mappings++; - mp->vlan_qos = vlan_qos; + WRITE_ONCE(mp->vlan_qos, vlan_qos); return 0; } - mp = mp->next; + mp = rtnl_dereference(mp->next); } /* Create a new mapping then. */ - mp = vlan->egress_priority_map[skb_prio & 0xF]; np = kmalloc_obj(struct vlan_priority_tci_mapping); if (!np) return -ENOBUFS; - np->next = mp; np->priority = skb_prio; np->vlan_qos = vlan_qos; - /* Before inserting this element in hash table, make sure all its fields - * are committed to memory. - * coupled with smp_rmb() in vlan_dev_get_egress_qos_mask() - */ - smp_wmb(); - vlan->egress_priority_map[skb_prio & 0xF] = np; + 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++; return 0; @@ -604,11 +599,17 @@ void vlan_dev_free_egress_priority(const struct net_device *dev) int i; for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) { - while ((pm = vlan->egress_priority_map[i]) != NULL) { - vlan->egress_priority_map[i] = pm->next; - kfree(pm); + pm = rtnl_dereference(vlan->egress_priority_map[i]); + RCU_INIT_POINTER(vlan->egress_priority_map[i], NULL); + while (pm) { + struct vlan_priority_tci_mapping *next; + + next = rtnl_dereference(pm->next); + kfree_rcu(pm, rcu); + pm = next; } } + vlan->nr_egress_mappings = 0; } static void vlan_dev_uninit(struct net_device *dev) diff --git a/net/8021q/vlan_netlink.c b/net/8021q/vlan_netlink.c index a000b1ef05206..a5b16833e2cee 100644 --- a/net/8021q/vlan_netlink.c +++ b/net/8021q/vlan_netlink.c @@ -260,13 +260,15 @@ static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev) goto nla_put_failure; for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) { - for (pm = vlan->egress_priority_map[i]; pm; - pm = pm->next) { - if (!pm->vlan_qos) + for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm; + pm = rcu_dereference_rtnl(pm->next)) { + u16 vlan_qos = READ_ONCE(pm->vlan_qos); + + if (!vlan_qos) continue; m.from = pm->priority; - m.to = (pm->vlan_qos >> 13) & 0x7; + m.to = (vlan_qos >> 13) & 0x7; if (nla_put(skb, IFLA_VLAN_QOS_MAPPING, sizeof(m), &m)) goto nla_put_failure; diff --git a/net/8021q/vlanproc.c b/net/8021q/vlanproc.c index fa67374bda494..0e424e0895b7e 100644 --- a/net/8021q/vlanproc.c +++ b/net/8021q/vlanproc.c @@ -262,15 +262,19 @@ static int vlandev_seq_show(struct seq_file *seq, void *offset) vlan->ingress_priority_map[7]); seq_printf(seq, " EGRESS priority mappings: "); + rcu_read_lock(); for (i = 0; i < 16; i++) { - const struct vlan_priority_tci_mapping *mp - = vlan->egress_priority_map[i]; + const struct vlan_priority_tci_mapping *mp = + rcu_dereference(vlan->egress_priority_map[i]); while (mp) { + u16 vlan_qos = READ_ONCE(mp->vlan_qos); + seq_printf(seq, "%u:%d ", - mp->priority, ((mp->vlan_qos >> 13) & 0x7)); - mp = mp->next; + mp->priority, ((vlan_qos >> 13) & 0x7)); + mp = rcu_dereference(mp->next); } } + rcu_read_unlock(); seq_puts(seq, "\n"); return 0;