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tcp: factorize logic into tcp_epollin_ready()
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Both tcp_data_ready() and tcp_stream_is_readable() share the same logic.

Add tcp_epollin_ready() helper to avoid duplication.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Feb 13, 2021
1 parent f969dc5 commit 05dc72a
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Showing 3 changed files with 19 additions and 22 deletions.
12 changes: 12 additions & 0 deletions include/net/tcp.h
Original file line number Diff line number Diff line change
Expand Up @@ -1442,6 +1442,18 @@ static inline bool tcp_rmem_pressure(const struct sock *sk)
return atomic_read(&sk->sk_rmem_alloc) > threshold;
}

static inline bool tcp_epollin_ready(const struct sock *sk, int target)
{
const struct tcp_sock *tp = tcp_sk(sk);
int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);

if (avail <= 0)
return false;

return (avail >= target) || tcp_rmem_pressure(sk) ||
(tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
}

extern void tcp_openreq_init_rwin(struct request_sock *req,
const struct sock *sk_listener,
const struct dst_entry *dst);
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18 changes: 5 additions & 13 deletions net/ipv4/tcp.c
Original file line number Diff line number Diff line change
Expand Up @@ -481,19 +481,11 @@ static void tcp_tx_timestamp(struct sock *sk, u16 tsflags)
}
}

static inline bool tcp_stream_is_readable(const struct tcp_sock *tp,
int target, struct sock *sk)
static bool tcp_stream_is_readable(struct sock *sk, int target)
{
int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);

if (avail > 0) {
if (avail >= target)
return true;
if (tcp_rmem_pressure(sk))
return true;
if (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss)
return true;
}
if (tcp_epollin_ready(sk, target))
return true;

if (sk->sk_prot->stream_memory_read)
return sk->sk_prot->stream_memory_read(sk);
return false;
Expand Down Expand Up @@ -568,7 +560,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
tp->urg_data)
target++;

if (tcp_stream_is_readable(tp, target, sk))
if (tcp_stream_is_readable(sk, target))
mask |= EPOLLIN | EPOLLRDNORM;

if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
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11 changes: 2 additions & 9 deletions net/ipv4/tcp_input.c
Original file line number Diff line number Diff line change
Expand Up @@ -4924,15 +4924,8 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)

void tcp_data_ready(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
int avail = tp->rcv_nxt - tp->copied_seq;

if (avail < sk->sk_rcvlowat && !tcp_rmem_pressure(sk) &&
!sock_flag(sk, SOCK_DONE) &&
tcp_receive_window(tp) > inet_csk(sk)->icsk_ack.rcv_mss)
return;

sk->sk_data_ready(sk);
if (tcp_epollin_ready(sk, sk->sk_rcvlowat))
sk->sk_data_ready(sk);
}

static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
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