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mptcp: preserve MSG_EOR semantics in sendmsg path

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Extend MPTCP's sendmsg handling to recognize and honor the MSG_EOR flag,
which marks the end of a record for application-level message boundaries.

Data fragments tagged with MSG_EOR are explicitly marked in the
mptcp_data_frag structure and skb context to prevent unintended
coalescing with subsequent data chunks. This ensures the intent of
applications using MSG_EOR is preserved across MPTCP subflows,
maintaining consistent message segmentation behavior.

Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-2-b0b33bea3fed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Gang Yan 2026-04-03 13:29:28 +02:00 committed by Jakub Kicinski
parent 00d46be3c3
commit 7fb2f5f964
2 changed files with 22 additions and 4 deletions
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24
net/mptcp/protocol.c
View File

@ -1005,7 +1005,8 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
const struct page_frag *pfrag,
const struct mptcp_data_frag *df)
{
return df && pfrag->page == df->page &&
return df && !df->eor &&
pfrag->page == df->page &&
pfrag->size - pfrag->offset > 0 &&
pfrag->offset == (df->offset + df->data_len) &&
df->data_seq + df->data_len == msk->write_seq;
@ -1147,6 +1148,7 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag,
dfrag->offset = offset + sizeof(struct mptcp_data_frag);
dfrag->already_sent = 0;
dfrag->page = pfrag->page;
dfrag->eor = 0;
return dfrag;
}
@ -1408,6 +1410,13 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
mptcp_update_infinite_map(msk, ssk, mpext);
trace_mptcp_sendmsg_frag(mpext);
mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
/* if this is the last chunk of a dfrag with MSG_EOR set,
* mark the skb to prevent coalescing with subsequent data.
*/
if (dfrag->eor && info->sent + copy >= dfrag->data_len)
TCP_SKB_CB(skb)->eor = 1;
return copy;
}
@ -1868,7 +1877,8 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
long timeo;
/* silently ignore everything else */
msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | MSG_FASTOPEN;
msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
MSG_FASTOPEN | MSG_EOR;
lock_sock(sk);
@ -1975,8 +1985,16 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
goto do_error;
}
if (copied)
if (copied) {
/* mark the last dfrag with EOR if MSG_EOR was set */
if (msg->msg_flags & MSG_EOR) {
struct mptcp_data_frag *dfrag = mptcp_pending_tail(sk);
if (dfrag)
dfrag->eor = 1;
}
__mptcp_push_pending(sk, msg->msg_flags);
}
out:
release_sock(sk);

2
net/mptcp/protocol.h
View File

@ -264,7 +264,7 @@ struct mptcp_data_frag {
u16 data_len;
u16 offset;
u8 overhead;
u8 __unused;
u8 eor; /* currently using 1 bit */
u16 already_sent;
struct page *page;
};