net: annotate lockless accesses to sk->sk_ack_backlog

sk->sk_ack_backlog can be read without any lock being held.
We need to use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing
and/or potential KCSAN warnings.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sock.h b/include/net/sock.h
index f2f853439b6576925e39f6db010964762e39ccf2..a126784aa7d9b6f59c8937c8c94d5bd7843988a4 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -859,17 +859,17 @@ static inline gfp_t sk_gfp_mask(const struct sock *sk, gfp_t gfp_mask)
 
 static inline void sk_acceptq_removed(struct sock *sk)
 {
-       sk->sk_ack_backlog--;
+       WRITE_ONCE(sk->sk_ack_backlog, sk->sk_ack_backlog - 1);
 }
 
 static inline void sk_acceptq_added(struct sock *sk)
 {
-       sk->sk_ack_backlog++;
+       WRITE_ONCE(sk->sk_ack_backlog, sk->sk_ack_backlog + 1);
 }
 
 static inline bool sk_acceptq_is_full(const struct sock *sk)
 {
-       return sk->sk_ack_backlog > sk->sk_max_ack_backlog;
+       return READ_ONCE(sk->sk_ack_backlog) > sk->sk_max_ack_backlog;
 }
 
 /*

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1dd25189d83f2c7404336f8378be23c4beaa7ed7..68375f7ffdce1fbbb4cf443660703c98b61fd9e3 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3225,7 +3225,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
                 * tcpi_unacked -> Number of children ready for accept()
                 * tcpi_sacked  -> max backlog
                 */
-               info->tcpi_unacked = sk->sk_ack_backlog;
+               info->tcpi_unacked = READ_ONCE(sk->sk_ack_backlog);
                info->tcpi_sacked = sk->sk_max_ack_backlog;
                return;
        }

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index 549506162ddeca22f6dd87dfe1c5c13cea6e2b69..edfbab54c46f4cac1b0a7960718d0b6308978957 100644 (file)
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -21,7 +21,7 @@ static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
        struct tcp_info *info = _info;
 
        if (inet_sk_state_load(sk) == TCP_LISTEN) {
-               r->idiag_rqueue = sk->sk_ack_backlog;
+               r->idiag_rqueue = READ_ONCE(sk->sk_ack_backlog);
                r->idiag_wqueue = sk->sk_max_ack_backlog;
        } else if (sk->sk_type == SOCK_STREAM) {
                const struct tcp_sock *tp = tcp_sk(sk);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 899e100a68e6ab8fcf7b2c4d2a9d179745a782b5..92282f98dc82290bfaf53acc050182e4cc3be1eb 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2451,7 +2451,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
 
        state = inet_sk_state_load(sk);
        if (state == TCP_LISTEN)
-               rx_queue = sk->sk_ack_backlog;
+               rx_queue = READ_ONCE(sk->sk_ack_backlog);
        else
                /* Because we don't lock the socket,
                 * we might find a transient negative value.

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 4804b6dc5e6519a457e631bc1438a14f85477567..81f51335e326fad57d3e0e1ce23926b276e95e92 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1891,7 +1891,7 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
 
        state = inet_sk_state_load(sp);
        if (state == TCP_LISTEN)
-               rx_queue = sp->sk_ack_backlog;
+               rx_queue = READ_ONCE(sp->sk_ack_backlog);
        else
                /* Because we don't lock the socket,
                 * we might find a transient negative value.

diff --git a/net/sched/em_meta.c b/net/sched/em_meta.c
index 3177dcb173161629a801278db38fabeb6fcdbdd9..ebb6e2430861d23a42431e4143f229395d9321c5 100644 (file)
--- a/net/sched/em_meta.c
+++ b/net/sched/em_meta.c
@@ -521,7 +521,7 @@ META_COLLECTOR(int_sk_ack_bl)
                *err = -1;
                return;
        }
-       dst->value = sk->sk_ack_backlog;
+       dst->value = READ_ONCE(sk->sk_ack_backlog);
 }
 
 META_COLLECTOR(int_sk_max_ack_bl)

diff --git a/net/sctp/diag.c b/net/sctp/diag.c
index 0851166b917597b08becf9bf9d5873287b375828..f873f15407de4e7d9a246d41e07602f33da8064d 100644 (file)
--- a/net/sctp/diag.c
+++ b/net/sctp/diag.c
@@ -425,7 +425,7 @@ static void sctp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
                r->idiag_rqueue = atomic_read(&infox->asoc->rmem_alloc);
                r->idiag_wqueue = infox->asoc->sndbuf_used;
        } else {
-               r->idiag_rqueue = sk->sk_ack_backlog;
+               r->idiag_rqueue = READ_ONCE(sk->sk_ack_backlog);
                r->idiag_wqueue = sk->sk_max_ack_backlog;
        }
        if (infox->sctpinfo)