Re: [PATCH bpf v3 2/2] bpf, sockmap: sk_prot needs inuse_idx set for proc stats
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2021-07-12 07:32:39
Also in:
bpf
On Tue, Jul 06, 2021 at 06:31 PM CEST, John Fastabend wrote:
quoted hunk ↗ jump to hunk
Proc socket stats use sk_prot->inuse_idx value to record inuse sock stats. We currently do not set this correctly from sockmap side. The result is reading sock stats '/proc/net/sockstat' gives incorrect values. The socket counter is incremented correctly, but because we don't set the counter correctly when we replace sk_prot we may omit the decrement. Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: John Fastabend <john.fastabend@gmail.com> --- net/core/sock_map.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 60decd6420ca..27bdf768aa8c 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c@@ -185,10 +185,19 @@ static void sock_map_unref(struct sock *sk, void *link_raw) static int sock_map_init_proto(struct sock *sk, struct sk_psock *psock) { + int err; +#ifdef CONFIG_PROC_FS + int idx = sk->sk_prot->inuse_idx; +#endif if (!sk->sk_prot->psock_update_sk_prot) return -EINVAL; psock->psock_update_sk_prot = sk->sk_prot->psock_update_sk_prot; - return sk->sk_prot->psock_update_sk_prot(sk, psock, false); + err = sk->sk_prot->psock_update_sk_prot(sk, psock, false); +#ifdef CONFIG_PROC_FS + if (!err) + sk->sk_prot->inuse_idx = idx; +#endif + return err; } static struct sk_psock *sock_map_psock_get_checked(struct sock *sk)
We could initialize inuse_idx just once in {tcp,udp}_bpf_rebuild_protos,
if we changed {tcp,udp}_bpf_v4_build_proto to be a late_initcall, so
that it runs after inet_init when {tcp,udp}_prot and udp_prot are
already registered and have inuse_idx assigned.