diff options
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 71b76e98371a..64f93668a845 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4890,12 +4890,23 @@ static int tcp_prune_queue(struct sock *sk, const struct sk_buff *in_skb); /* Check if this incoming skb can be added to socket receive queues * while satisfying sk->sk_rcvbuf limit. + * + * In theory we should use skb->truesize, but this can cause problems + * when applications use too small SO_RCVBUF values. + * When LRO / hw gro is used, the socket might have a high tp->scaling_ratio, + * allowing RWIN to be close to available space. + * Whenever the receive queue gets full, we can receive a small packet + * filling RWIN, but with a high skb->truesize, because most NIC use 4K page + * plus sk_buff metadata even when receiving less than 1500 bytes of payload. + * + * Note that we use skb->len to decide to accept or drop this packet, + * but sk->sk_rmem_alloc is the sum of all skb->truesize. */ static bool tcp_can_ingest(const struct sock *sk, const struct sk_buff *skb) { - unsigned int new_mem = atomic_read(&sk->sk_rmem_alloc) + skb->truesize; + unsigned int rmem = atomic_read(&sk->sk_rmem_alloc); - return new_mem <= sk->sk_rcvbuf; + return rmem + skb->len <= sk->sk_rcvbuf; } static int tcp_try_rmem_schedule(struct sock *sk, const struct sk_buff *skb, |