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tcp: annotate sk->sk_sndbuf lockless reads
For the sake of tcp_poll(), there are few places where we fetch sk->sk_sndbuf while this field can change from IRQ or other cpu. We need to add READ_ONCE() annotations, and also make sure write sides use corresponding WRITE_ONCE() to avoid store-tearing. Note that other transports probably need similar fixes. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -883,7 +883,7 @@ static inline int sk_stream_min_wspace(const struct sock *sk)
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static inline int sk_stream_wspace(const struct sock *sk)
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{
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return sk->sk_sndbuf - sk->sk_wmem_queued;
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return READ_ONCE(sk->sk_sndbuf) - sk->sk_wmem_queued;
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}
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void sk_stream_write_space(struct sock *sk);
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@ -1207,7 +1207,7 @@ static inline void sk_refcnt_debug_release(const struct sock *sk)
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static inline bool __sk_stream_memory_free(const struct sock *sk, int wake)
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{
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if (sk->sk_wmem_queued >= sk->sk_sndbuf)
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if (sk->sk_wmem_queued >= READ_ONCE(sk->sk_sndbuf))
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return false;
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return sk->sk_prot->stream_memory_free ?
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@ -2220,10 +2220,14 @@ static inline void sk_wake_async(const struct sock *sk, int how, int band)
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static inline void sk_stream_moderate_sndbuf(struct sock *sk)
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{
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if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK)) {
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sk->sk_sndbuf = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1);
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sk->sk_sndbuf = max_t(u32, sk->sk_sndbuf, SOCK_MIN_SNDBUF);
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}
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u32 val;
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if (sk->sk_userlocks & SOCK_SNDBUF_LOCK)
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return;
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val = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1);
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WRITE_ONCE(sk->sk_sndbuf, max_t(u32, val, SOCK_MIN_SNDBUF));
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}
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struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
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@ -2251,7 +2255,7 @@ bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag);
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*/
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static inline bool sock_writeable(const struct sock *sk)
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{
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return refcount_read(&sk->sk_wmem_alloc) < (sk->sk_sndbuf >> 1);
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return refcount_read(&sk->sk_wmem_alloc) < (READ_ONCE(sk->sk_sndbuf) >> 1);
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}
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static inline gfp_t gfp_any(void)
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@ -4258,7 +4258,8 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
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case SO_SNDBUF:
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val = min_t(u32, val, sysctl_wmem_max);
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sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
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sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
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WRITE_ONCE(sk->sk_sndbuf,
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max_t(int, val * 2, SOCK_MIN_SNDBUF));
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break;
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case SO_MAX_PACING_RATE: /* 32bit version */
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if (val != ~0U)
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@ -785,7 +785,8 @@ set_sndbuf:
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*/
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val = min_t(int, val, INT_MAX / 2);
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sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
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sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
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WRITE_ONCE(sk->sk_sndbuf,
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max_t(int, val * 2, SOCK_MIN_SNDBUF));
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/* Wake up sending tasks if we upped the value. */
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sk->sk_write_space(sk);
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break;
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@ -2089,8 +2090,10 @@ EXPORT_SYMBOL(sock_i_ino);
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struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
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gfp_t priority)
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{
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if (force || refcount_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) {
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if (force ||
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refcount_read(&sk->sk_wmem_alloc) < READ_ONCE(sk->sk_sndbuf)) {
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struct sk_buff *skb = alloc_skb(size, priority);
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if (skb) {
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skb_set_owner_w(skb, sk);
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return skb;
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@ -2191,7 +2194,7 @@ static long sock_wait_for_wmem(struct sock *sk, long timeo)
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break;
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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if (refcount_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf)
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if (refcount_read(&sk->sk_wmem_alloc) < READ_ONCE(sk->sk_sndbuf))
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break;
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if (sk->sk_shutdown & SEND_SHUTDOWN)
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break;
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@ -2226,7 +2229,7 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,
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if (sk->sk_shutdown & SEND_SHUTDOWN)
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goto failure;
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if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf)
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if (sk_wmem_alloc_get(sk) < READ_ONCE(sk->sk_sndbuf))
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break;
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sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
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@ -2807,7 +2810,7 @@ static void sock_def_write_space(struct sock *sk)
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/* Do not wake up a writer until he can make "significant"
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* progress. --DaveM
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*/
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if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf) {
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if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= READ_ONCE(sk->sk_sndbuf)) {
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wq = rcu_dereference(sk->sk_wq);
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if (skwq_has_sleeper(wq))
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wake_up_interruptible_sync_poll(&wq->wait, EPOLLOUT |
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@ -3207,7 +3210,7 @@ void sk_get_meminfo(const struct sock *sk, u32 *mem)
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mem[SK_MEMINFO_RMEM_ALLOC] = sk_rmem_alloc_get(sk);
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mem[SK_MEMINFO_RCVBUF] = READ_ONCE(sk->sk_rcvbuf);
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mem[SK_MEMINFO_WMEM_ALLOC] = sk_wmem_alloc_get(sk);
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mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
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mem[SK_MEMINFO_SNDBUF] = READ_ONCE(sk->sk_sndbuf);
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mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
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mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
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mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
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@ -450,7 +450,7 @@ void tcp_init_sock(struct sock *sk)
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icsk->icsk_sync_mss = tcp_sync_mss;
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sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
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WRITE_ONCE(sk->sk_sndbuf, sock_net(sk)->ipv4.sysctl_tcp_wmem[1]);
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WRITE_ONCE(sk->sk_rcvbuf, sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
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sk_sockets_allocated_inc(sk);
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@ -359,7 +359,8 @@ static void tcp_sndbuf_expand(struct sock *sk)
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sndmem *= nr_segs * per_mss;
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if (sk->sk_sndbuf < sndmem)
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sk->sk_sndbuf = min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]);
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WRITE_ONCE(sk->sk_sndbuf,
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min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]));
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}
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/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
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