From 2cbcd3c19841b6b025d9d9a27c09681bd83ae156 Mon Sep 17 00:00:00 2001
From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Sun, 30 Nov 2014 13:43:52 +0000
Subject: [PATCH] Merge from projects/sendfile:

- Provide pru_ready function for TCP.
- Don't call tcp_output() from tcp_usr_send() if no ready data was put
  into the socket buffer.
- In case of dropped connection don't try to m_freem() not ready data.

Sponsored by:	Nginx, Inc.
Sponsored by:	Netflix
---
 sys/netinet/tcp_usrreq.c | 46 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index 8b4048c0a1d..dee1c33186a 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -821,7 +821,11 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf *m,
 	if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 		if (control)
 			m_freem(control);
-		if (m)
+		/*
+		 * In case of PRUS_NOTREADY, tcp_usr_ready() is responsible
+		 * for freeing memory.
+		 */
+		if (m && (flags & PRUS_NOTREADY) == 0)
 			m_freem(m);
 		error = ECONNRESET;
 		goto out;
@@ -875,7 +879,8 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf *m,
 			socantsendmore(so);
 			tcp_usrclosed(tp);
 		}
-		if (!(inp->inp_flags & INP_DROPPED)) {
+		if (!(inp->inp_flags & INP_DROPPED) &&
+		    !(flags & PRUS_NOTREADY)) {
 			if (flags & PRUS_MORETOCOME)
 				tp->t_flags |= TF_MORETOCOME;
 			error = tcp_output(tp);
@@ -926,9 +931,11 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf *m,
 			tcp_mss(tp, -1);
 		}
 		tp->snd_up = tp->snd_una + sbavail(&so->so_snd);
-		tp->t_flags |= TF_FORCEDATA;
-		error = tcp_output(tp);
-		tp->t_flags &= ~TF_FORCEDATA;
+		if (!(flags & PRUS_NOTREADY)) {
+			tp->t_flags |= TF_FORCEDATA;
+			error = tcp_output(tp);
+			tp->t_flags &= ~TF_FORCEDATA;
+		}
 	}
 out:
 	TCPDEBUG2((flags & PRUS_OOB) ? PRU_SENDOOB :
@@ -939,6 +946,33 @@ out:
 	return (error);
 }
 
+static int
+tcp_usr_ready(struct socket *so, struct mbuf *m, int count)
+{
+	struct inpcb *inp;
+	struct tcpcb *tp;
+	int error;
+
+	inp = sotoinpcb(so);
+	INP_WLOCK(inp);
+	if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
+		INP_WUNLOCK(inp);
+		for (int i = 0; i < count; i++)
+			m = m_free(m);
+		return (ECONNRESET);
+	}
+	tp = intotcpcb(inp);
+
+	SOCKBUF_LOCK(&so->so_snd);
+	error = sbready(&so->so_snd, m, count);
+	SOCKBUF_UNLOCK(&so->so_snd);
+	if (error == 0)
+		error = tcp_output(tp);
+	INP_WUNLOCK(inp);
+
+	return (error);
+}
+
 /*
  * Abort the TCP.  Drop the connection abruptly.
  */
@@ -1073,6 +1107,7 @@ struct pr_usrreqs tcp_usrreqs = {
 	.pru_rcvd =		tcp_usr_rcvd,
 	.pru_rcvoob =		tcp_usr_rcvoob,
 	.pru_send =		tcp_usr_send,
+	.pru_ready =		tcp_usr_ready,
 	.pru_shutdown =		tcp_usr_shutdown,
 	.pru_sockaddr =		in_getsockaddr,
 	.pru_sosetlabel =	in_pcbsosetlabel,
@@ -1095,6 +1130,7 @@ struct pr_usrreqs tcp6_usrreqs = {
 	.pru_rcvd =		tcp_usr_rcvd,
 	.pru_rcvoob =		tcp_usr_rcvoob,
 	.pru_send =		tcp_usr_send,
+	.pru_ready =		tcp_usr_ready,
 	.pru_shutdown =		tcp_usr_shutdown,
 	.pru_sockaddr =		in6_mapped_sockaddr,
 	.pru_sosetlabel =	in_pcbsosetlabel,