[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240711124645.GC8788@kernel.org>
Date: Thu, 11 Jul 2024 13:46:45 +0100
From: Simon Horman <horms@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH v2 net-next] net: reduce rtnetlink_rcv_msg() stack usage
On Wed, Jul 10, 2024 at 03:16:53PM +0000, Eric Dumazet wrote:
> 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@...gle.com>
Reviewed-by: Simon Horman <horms@...nel.org>
> ---
> net/core/rtnetlink.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index eabfc8290f5e29f2ef3e5c1481715ae9056ea689..87e67194f24046a8420bbb51c19fb0a686b9b06b 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -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);
I guess that in practice we can break here.
But perhaps there is some case where there is more than one
IFLA_EXT_MASK attribute and it changes behaviour.
> }
>
> if (!ext_filter_mask)
> --
> 2.45.2.993.g49e7a77208-goog
>
>
Powered by blists - more mailing lists