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net: reduce rtnetlink_rcv_msg() stack usage

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IFLA_MAX is increasing slowly but surely.

Some compilers use more than 512 bytes of stack in rtnetlink_rcv_msg()
because it calls rtnl_calcit() for RTM_GETLINK message.

Use noinline_for_stack attribute to not inline rtnl_calcit(),
and directly use nla_for_each_attr_type() (Jakub suggestion)
because we only care about IFLA_EXT_MASK at this stage.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240710151653.3786604-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-07-10 15:16:53 +00:00 committed by Jakub Kicinski
parent b07593edd2
commit cef4902b0f
1 changed files with 12 additions and 6 deletions
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18
net/core/rtnetlink.c
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@ -3969,22 +3969,28 @@ static int rtnl_dellinkprop(struct sk_buff *skb, struct nlmsghdr *nlh,
return rtnl_linkprop(RTM_DELLINKPROP, skb, nlh, extack);
}
static u32 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)
static noinline_for_stack u32 rtnl_calcit(struct sk_buff *skb,
struct nlmsghdr *nlh)
{
struct net *net = sock_net(skb->sk);
size_t min_ifinfo_dump_size = 0;
struct nlattr *tb[IFLA_MAX+1];
u32 ext_filter_mask = 0;
struct net_device *dev;
int hdrlen;
struct nlattr *nla;
int hdrlen, rem;
/* Same kernel<->userspace interface hack as in rtnl_dump_ifinfo. */
hdrlen = nlmsg_len(nlh) < sizeof(struct ifinfomsg) ?
sizeof(struct rtgenmsg) : sizeof(struct ifinfomsg);
if (nlmsg_parse_deprecated(nlh, hdrlen, tb, IFLA_MAX, ifla_policy, NULL) >= 0) {
if (tb[IFLA_EXT_MASK])
ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
return NLMSG_GOODSIZE;
nla_for_each_attr_type(nla, IFLA_EXT_MASK,
nlmsg_attrdata(nlh, hdrlen),
nlmsg_attrlen(nlh, hdrlen), rem) {
if (nla_len(nla) == sizeof(u32))
ext_filter_mask = nla_get_u32(nla);
}
if (!ext_filter_mask)