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rtnetlink: add RTEXT_FILTER_NAME_ONLY support

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iproute2 can spend considerable amount of time in ll_init_map()
or ll_link_get() to dump verbose netdev attributes, contributing
to RTNL pressure.

Add RTEXT_FILTER_NAME_ONLY new flag so that rtnl_fill_ifinfo()
limits its output to:

- struct nlmsghdr
- IFLA_IFNAME
- IFLA_PROP_LIST (alternate names)

We can later avoid using RTNL when RTEXT_FILTER_NAME_ONLY
is requested, as none of these attributes need RTNL.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260511070244.971028-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2026-05-11 07:02:44 +00:00
committed by Jakub Kicinski
parent 9edbdd2c9d
commit b588019e85
2 changed files with 23 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/uapi/linux/rtnetlink.h
View File

@@ -840,6 +840,7 @@ enum {
#define RTEXT_FILTER_CFM_CONFIG (1 << 5)
#define RTEXT_FILTER_CFM_STATUS (1 << 6)
#define RTEXT_FILTER_MST (1 << 7)
#define RTEXT_FILTER_NAME_ONLY (1 << 8)
/* End of information exported to user level */

31
net/core/rtnetlink.c
View File

@@ -1295,7 +1295,12 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
size = NLMSG_ALIGN(sizeof(struct ifinfomsg))
+ nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
+ nla_total_size(IFALIASZ) /* IFLA_IFALIAS */
+ rtnl_prop_list_size(dev);
if (ext_filter_mask & RTEXT_FILTER_NAME_ONLY)
return size;
size += nla_total_size(IFALIASZ) /* IFLA_IFALIAS */
+ nla_total_size(IFNAMSIZ) /* IFLA_QDISC */
+ nla_total_size_64bit(sizeof(struct rtnl_link_ifmap))
+ nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
@@ -1342,7 +1347,6 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
+ nla_total_size(4) /* IFLA_CARRIER_DOWN_COUNT */
+ nla_total_size(4) /* IFLA_MIN_MTU */
+ nla_total_size(4) /* IFLA_MAX_MTU */
+ rtnl_prop_list_size(dev)
+ nla_total_size(MAX_ADDR_LEN) /* IFLA_PERM_ADDRESS */
+ rtnl_devlink_port_size(dev)
+ rtnl_dpll_pin_size(dev)
@@ -1941,15 +1945,18 @@ static int rtnl_fill_alt_ifnames(struct sk_buff *skb,
struct netdev_name_node *name_node;
int count = 0;
rcu_read_lock();
list_for_each_entry_rcu(name_node, &dev->name_node->list, list) {
if (nla_put_string(skb, IFLA_ALT_IFNAME, name_node->name))
if (nla_put_string(skb, IFLA_ALT_IFNAME, name_node->name)) {
rcu_read_unlock();
return -EMSGSIZE;
}
count++;
}
rcu_read_unlock();
return count;
}
/* RCU protected. */
static int rtnl_fill_prop_list(struct sk_buff *skb,
const struct net_device *dev)
{
@@ -2072,13 +2079,20 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
ifm->ifi_flags = netif_get_flags(dev);
ifm->ifi_change = change;
if (tgt_netnsid >= 0 && nla_put_s32(skb, IFLA_TARGET_NETNSID, tgt_netnsid))
goto nla_put_failure;
netdev_copy_name(dev, devname);
if (nla_put_string(skb, IFLA_IFNAME, devname))
goto nla_put_failure;
if (rtnl_fill_prop_list(skb, dev))
goto nla_put_failure;
if (ext_filter_mask & RTEXT_FILTER_NAME_ONLY)
goto end;
if (tgt_netnsid >= 0 &&
nla_put_s32(skb, IFLA_TARGET_NETNSID, tgt_netnsid))
goto nla_put_failure;
if (nla_put_u32(skb, IFLA_TXQLEN, READ_ONCE(dev->tx_queue_len)) ||
nla_put_u8(skb, IFLA_OPERSTATE,
netif_running(dev) ? READ_ONCE(dev->operstate) :
@@ -2191,8 +2205,6 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
goto nla_put_failure_rcu;
if (rtnl_fill_link_ifmap(skb, dev))
goto nla_put_failure_rcu;
if (rtnl_fill_prop_list(skb, dev))
goto nla_put_failure_rcu;
rcu_read_unlock();
if (dev->dev.parent &&
@@ -2211,6 +2223,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
if (rtnl_fill_dpll_pin(skb, dev))
goto nla_put_failure;
end:
nlmsg_end(skb, nlh);
return 0;