From: Eric Dumazet
> Sent: 15 September 2016 16:13
> If a TCP socket gets a large write queue, an overflow can happen
> in a test in __tcp_retransmit_skb() preventing all retransmits.
...
> if (atomic_read(&sk->sk_wmem_alloc) >
> - min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf))
> + min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2),
> + sk->sk_sndbuf))
> return -EAGAIN;
Might it also be better to split that test to (say):
u32 wmem_alloc = atomic_read(&sk->sk_wmem_alloc);
if (unlikely((wmem_alloc > sk->sk_sndbuf))
return -EAGAIN;
if (unlikely(wmem_alloc > sk->sk_wmem_queued + (sk->sk_wmem_queued >>
2)))
return -EAGAIN;
It might even be worth splitting the second test as:
if (unlikely(wmem_alloc > sk->sk_wmem_queued)
&& wmem_alloc > sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2))
return -EAGAIN;
David
