path: root/include/linux/sock_diag.h
diff options
authorDaniel Borkmann <daniel@iogearbox.net>2020-09-30 17:18:16 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-09-30 11:50:35 -0700
commit92acdc58ab11af66fcaef485433fde61b5e32fac (patch)
treeb43409d1e58f0d4a94935a563915308a5d5cabe3 /include/linux/sock_diag.h
parentbpf: Add classid helper only based on skb->sk (diff)
bpf, net: Rework cookie generator as per-cpu one
With its use in BPF, the cookie generator can be called very frequently in particular when used out of cgroup v2 hooks (e.g. connect / sendmsg) and attached to the root cgroup, for example, when used in v1/v2 mixed environments. In particular, when there's a high churn on sockets in the system there can be many parallel requests to the bpf_get_socket_cookie() and bpf_get_netns_cookie() helpers which then cause contention on the atomic counter. As similarly done in f991bd2e1421 ("fs: introduce a per-cpu last_ino allocator"), add a small helper library that both can use for the 64 bit counters. Given this can be called from different contexts, we also need to deal with potential nested calls even though in practice they are considered extremely rare. One idea as suggested by Eric Dumazet was to use a reverse counter for this situation since we don't expect 64 bit overflows anyways; that way, we can avoid bigger gaps in the 64 bit counter space compared to just batch-wise increase. Even on machines with small number of cores (e.g. 4) the cookie generation shrinks from min/max/med/avg (ns) of 22/50/40/38.9 down to 10/35/14/17.3 when run in parallel from multiple CPUs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Link: https://lore.kernel.org/bpf/8a80b8d27d3c49f9a14e1d5213c19d8be87d1dc8.1601477936.git.daniel@iogearbox.net
Diffstat (limited to 'include/linux/sock_diag.h')
1 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index 15fe980a27ea..0b9ecd8cf979 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -25,7 +25,19 @@ void sock_diag_unregister(const struct sock_diag_handler *h);
void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
-u64 sock_gen_cookie(struct sock *sk);
+u64 __sock_gen_cookie(struct sock *sk);
+static inline u64 sock_gen_cookie(struct sock *sk)
+ u64 cookie;
+ preempt_disable();
+ cookie = __sock_gen_cookie(sk);
+ preempt_enable();
+ return cookie;
int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie);
void sock_diag_save_cookie(struct sock *sk, __u32 *cookie);