diff options
| author | Soheil Hassas Yeganeh <soheil@google.com> | 2019-10-10 23:27:02 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-10-13 11:16:25 -0700 |
| commit | c208bdb93788cfd7982c35480f98e75d658719a7 (patch) | |
| tree | f26d0a89710f3bef10119321319b02f2201fc136 | |
| parent | 524900a212f419ed4a73c909b2c957912d38f7c1 (diff) | |
tcp: improve recv_skip_hint for tcp_zerocopy_receive
tcp_zerocopy_receive() rounds down the zc->length a multiple of
PAGE_SIZE. This results in two issues:
- tcp_zerocopy_receive sets recv_skip_hint to the length of the
receive queue if the zc->length input is smaller than the
PAGE_SIZE, even though the data in receive queue could be
zerocopied.
- tcp_zerocopy_receive would set recv_skip_hint of 0, in cases
where we have a little bit of data after the perfectly-sized
packets.
To fix these issues, do not store the rounded down value in
zc->length. Round down the length passed to zap_page_range(),
and return min(inq, zc->length) when the zap_range is 0.
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/tcp.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f98a1882e537..9f41a76c1c54 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1739,8 +1739,8 @@ static int tcp_zerocopy_receive(struct sock *sk, struct tcp_zerocopy_receive *zc) { unsigned long address = (unsigned long)zc->address; + u32 length = 0, seq, offset, zap_len; const skb_frag_t *frags = NULL; - u32 length = 0, seq, offset; struct vm_area_struct *vma; struct sk_buff *skb = NULL; struct tcp_sock *tp; @@ -1767,12 +1767,12 @@ static int tcp_zerocopy_receive(struct sock *sk, seq = tp->copied_seq; inq = tcp_inq(sk); zc->length = min_t(u32, zc->length, inq); - zc->length &= ~(PAGE_SIZE - 1); - if (zc->length) { - zap_page_range(vma, address, zc->length); + zap_len = zc->length & ~(PAGE_SIZE - 1); + if (zap_len) { + zap_page_range(vma, address, zap_len); zc->recv_skip_hint = 0; } else { - zc->recv_skip_hint = inq; + zc->recv_skip_hint = zc->length; } ret = 0; while (length + PAGE_SIZE <= zc->length) { |