From a54d51fb2dfb846aedf3751af501e9688db447f5 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Jan 2024 20:17:49 +0000 Subject: udp: fix busy polling Generic sk_busy_loop_end() only looks at sk->sk_receive_queue for presence of packets. Problem is that for UDP sockets after blamed commit, some packets could be present in another queue: udp_sk(sk)->reader_queue In some cases, a busy poller could spin until timeout expiration, even if some packets are available in udp_sk(sk)->reader_queue. v3: - make sk_busy_loop_end() nicer (Willem) v2: - add a READ_ONCE(sk->sk_family) in sk_is_inet() to avoid KCSAN splats. - add a sk_is_inet() check in sk_is_udp() (Willem feedback) - add a sk_is_inet() check in sk_is_tcp(). Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception") Signed-off-by: Eric Dumazet Reviewed-by: Paolo Abeni Reviewed-by: Willem de Bruijn Reviewed-by: Kuniyuki Iwashima Signed-off-by: David S. Miller --- include/linux/skmsg.h | 6 ------ include/net/inet_sock.h | 5 ----- include/net/sock.h | 18 +++++++++++++++++- net/core/sock.c | 11 +++++++++-- 4 files changed, 26 insertions(+), 14 deletions(-) diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index 888a4b217829..e65ec3fd2799 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -505,12 +505,6 @@ static inline bool sk_psock_strp_enabled(struct sk_psock *psock) return !!psock->saved_data_ready; } -static inline bool sk_is_udp(const struct sock *sk) -{ - return sk->sk_type == SOCK_DGRAM && - sk->sk_protocol == IPPROTO_UDP; -} - #if IS_ENABLED(CONFIG_NET_SOCK_MSG) #define BPF_F_STRPARSER (1UL << 1) diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index aa86453f6b9b..d94c242eb3ed 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -307,11 +307,6 @@ static inline unsigned long inet_cmsg_flags(const struct inet_sock *inet) #define inet_assign_bit(nr, sk, val) \ assign_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags, val) -static inline bool sk_is_inet(struct sock *sk) -{ - return sk->sk_family == AF_INET || sk->sk_family == AF_INET6; -} - /** * sk_to_full_sk - Access to a full socket * @sk: pointer to a socket diff --git a/include/net/sock.h b/include/net/sock.h index a7f815c7cfdf..54ca8dcbfb43 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2765,9 +2765,25 @@ static inline void skb_setup_tx_timestamp(struct sk_buff *skb, __u16 tsflags) &skb_shinfo(skb)->tskey); } +static inline bool sk_is_inet(const struct sock *sk) +{ + int family = READ_ONCE(sk->sk_family); + + return family == AF_INET || family == AF_INET6; +} + static inline bool sk_is_tcp(const struct sock *sk) { - return sk->sk_type == SOCK_STREAM && sk->sk_protocol == IPPROTO_TCP; + return sk_is_inet(sk) && + sk->sk_type == SOCK_STREAM && + sk->sk_protocol == IPPROTO_TCP; +} + +static inline bool sk_is_udp(const struct sock *sk) +{ + return sk_is_inet(sk) && + sk->sk_type == SOCK_DGRAM && + sk->sk_protocol == IPPROTO_UDP; } static inline bool sk_is_stream_unix(const struct sock *sk) diff --git a/net/core/sock.c b/net/core/sock.c index 158dbdebce6a..0a7f46c37f0c 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -107,6 +107,7 @@ #include #include #include +#include #include #include #include @@ -4144,8 +4145,14 @@ bool sk_busy_loop_end(void *p, unsigned long start_time) { struct sock *sk = p; - return !skb_queue_empty_lockless(&sk->sk_receive_queue) || - sk_busy_loop_timeout(sk, start_time); + if (!skb_queue_empty_lockless(&sk->sk_receive_queue)) + return true; + + if (sk_is_udp(sk) && + !skb_queue_empty_lockless(&udp_sk(sk)->reader_queue)) + return true; + + return sk_busy_loop_timeout(sk, start_time); } EXPORT_SYMBOL(sk_busy_loop_end); #endif /* CONFIG_NET_RX_BUSY_POLL */ -- cgit