mirror of https://gitee.com/openkylin/linux.git
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>
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@ -1739,8 +1739,8 @@ static int tcp_zerocopy_receive(struct sock *sk,
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struct tcp_zerocopy_receive *zc)
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{
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unsigned long address = (unsigned long)zc->address;
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u32 length = 0, seq, offset, zap_len;
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const skb_frag_t *frags = NULL;
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u32 length = 0, seq, offset;
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struct vm_area_struct *vma;
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struct sk_buff *skb = NULL;
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struct tcp_sock *tp;
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@ -1767,12 +1767,12 @@ static int tcp_zerocopy_receive(struct sock *sk,
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seq = tp->copied_seq;
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inq = tcp_inq(sk);
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zc->length = min_t(u32, zc->length, inq);
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zc->length &= ~(PAGE_SIZE - 1);
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if (zc->length) {
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zap_page_range(vma, address, zc->length);
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zap_len = zc->length & ~(PAGE_SIZE - 1);
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if (zap_len) {
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zap_page_range(vma, address, zap_len);
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zc->recv_skip_hint = 0;
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} else {
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zc->recv_skip_hint = inq;
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zc->recv_skip_hint = zc->length;
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}
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ret = 0;
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while (length + PAGE_SIZE <= zc->length) {
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