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authorRocco Yue <rocco.yue@mediatek.com>2021-08-27 18:04:12 +0300
committerJakub Kicinski <kuba@kernel.org>2021-08-28 03:29:18 +0300
commit49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 (patch)
tree961d50c7c7821c8cf0cb427d209ef1a53174ab4b /tools/include
parent0975d8b4bfa011b2943c53d3c169277f5e3cf799 (diff)
downloadlinux-49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7.tar.xz
ipv6: add IFLA_INET6_RA_MTU to expose mtu value
The kernel provides a "/proc/sys/net/ipv6/conf/<iface>/mtu" file, which can temporarily record the mtu value of the last received RA message when the RA mtu value is lower than the interface mtu, but this proc has following limitations: (1) when the interface mtu (/sys/class/net/<iface>/mtu) is updeated, mtu6 (/proc/sys/net/ipv6/conf/<iface>/mtu) will be updated to the value of interface mtu; (2) mtu6 (/proc/sys/net/ipv6/conf/<iface>/mtu) only affect ipv6 connection, and not affect ipv4. Therefore, when the mtu option is carried in the RA message, there will be a problem that the user sometimes cannot obtain RA mtu value correctly by reading mtu6. After this patch set, if a RA message carries the mtu option, you can send a netlink msg which nlmsg_type is RTM_GETLINK, and then by parsing the attribute of IFLA_INET6_RA_MTU to get the mtu value carried in the RA message received on the inet6 device. In addition, you can also get a link notification when ra_mtu is updated so it doesn't have to poll. In this way, if the MTU values that the device receives from the network in the PCO IPv4 and the RA IPv6 procedures are different, the user can obtain the correct ipv6 ra_mtu value and compare the value of ra_mtu and ipv4 mtu, then the device can use the lower MTU value for both IPv4 and IPv6. Signed-off-by: Rocco Yue <rocco.yue@mediatek.com> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/r/20210827150412.9267-1-rocco.yue@mediatek.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'tools/include')
-rw-r--r--tools/include/uapi/linux/if_link.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/include/uapi/linux/if_link.h b/tools/include/uapi/linux/if_link.h
index eb15f319aa57..b3610fdd1fee 100644
--- a/tools/include/uapi/linux/if_link.h
+++ b/tools/include/uapi/linux/if_link.h
@@ -230,6 +230,7 @@ enum {
IFLA_INET6_ICMP6STATS, /* statistics (icmpv6) */
IFLA_INET6_TOKEN, /* device token */
IFLA_INET6_ADDR_GEN_MODE, /* implicit address generator mode */
+ IFLA_INET6_RA_MTU, /* mtu carried in the RA message */
__IFLA_INET6_MAX
};