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Coalesce and collapse of packets carrying MPTCP extensions is allowed when the newer packet has no extension or the extensions carried by both packets are equal. This allows merging of TSO packet trains and even cross-TSO packets, and does not require any additional action when moving data into existing SKBs. v3 -> v4: - allow collapsing, under mptcp_skb_can_collapse() constraint v5 -> v6: - clarify MPTCP skb extensions must always be cleared at allocation time Co-developed-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Multipath TCP
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*
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* Copyright (c) 2017 - 2019, Intel Corporation.
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*/
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#ifndef __NET_MPTCP_H
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#define __NET_MPTCP_H
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#include <linux/skbuff.h>
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#include <linux/types.h>
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/* MPTCP sk_buff extension data */
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struct mptcp_ext {
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u64 data_ack;
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u64 data_seq;
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u32 subflow_seq;
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u16 data_len;
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u8 use_map:1,
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dsn64:1,
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data_fin:1,
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use_ack:1,
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ack64:1,
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__unused:3;
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/* one byte hole */
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};
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#ifdef CONFIG_MPTCP
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/* move the skb extension owership, with the assumption that 'to' is
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* newly allocated
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*/
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static inline void mptcp_skb_ext_move(struct sk_buff *to,
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struct sk_buff *from)
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{
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if (!skb_ext_exist(from, SKB_EXT_MPTCP))
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return;
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if (WARN_ON_ONCE(to->active_extensions))
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skb_ext_put(to);
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to->active_extensions = from->active_extensions;
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to->extensions = from->extensions;
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from->active_extensions = 0;
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}
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static inline bool mptcp_ext_matches(const struct mptcp_ext *to_ext,
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const struct mptcp_ext *from_ext)
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{
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/* MPTCP always clears the ext when adding it to the skb, so
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* holes do not bother us here
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*/
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return !from_ext ||
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(to_ext && from_ext &&
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!memcmp(from_ext, to_ext, sizeof(struct mptcp_ext)));
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}
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/* check if skbs can be collapsed.
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* MPTCP collapse is allowed if neither @to or @from carry an mptcp data
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* mapping, or if the extension of @to is the same as @from.
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* Collapsing is not possible if @to lacks an extension, but @from carries one.
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*/
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static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
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const struct sk_buff *from)
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{
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return mptcp_ext_matches(skb_ext_find(to, SKB_EXT_MPTCP),
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skb_ext_find(from, SKB_EXT_MPTCP));
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}
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#else
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static inline void mptcp_skb_ext_move(struct sk_buff *to,
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const struct sk_buff *from)
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{
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}
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static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
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const struct sk_buff *from)
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{
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return true;
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}
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#endif /* CONFIG_MPTCP */
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#endif /* __NET_MPTCP_H */
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