From 7b5c2d1cd6cdf69430b3ad5234ae25a9037939b4 Mon Sep 17 00:00:00 2001
From: Thomas Schoebel-Theuer <schoebel@bell.site>
Date: Fri, 22 Nov 2013 08:09:58 +0100
Subject: [PATCH] net: find out current tcp send buffer space available

---
 kernel/mars_net.c | 21 +++++++++++++++++++++
 kernel/mars_net.h |  1 +
 2 files changed, 22 insertions(+)

diff --git a/kernel/mars_net.c b/kernel/mars_net.c
index d358578e..cb8f8995 100644
--- a/kernel/mars_net.c
+++ b/kernel/mars_net.c
@@ -354,6 +354,27 @@ done:
 }
 EXPORT_SYMBOL_GPL(mars_socket_is_alive);
 
+long mars_socket_send_space_available(struct mars_socket *msock)
+{
+	struct socket *raw_sock = msock->s_socket;
+	long res = 0;
+	if (!msock->s_alive || !raw_sock || !raw_sock->sk)
+		goto done;
+	if (unlikely(atomic_read(&msock->s_count) <= 0)) {
+		MARS_ERR("#%d bad nesting on msock = %p sock = %p\n", msock->s_debug_nr, msock, msock->s_socket);
+		goto done;
+	}
+
+	res = raw_sock->sk->sk_sndbuf - raw_sock->sk->sk_wmem_queued;
+	if (res < 0)
+		res = 0;
+	res += msock->s_pos;
+	
+done:
+	return res;
+}
+EXPORT_SYMBOL_GPL(mars_socket_send_space_available);
+
 static
 int _mars_send_raw(struct mars_socket *msock, const void *buf, int len)
 {
diff --git a/kernel/mars_net.h b/kernel/mars_net.h
index 98c0eb58..2cb3f553 100644
--- a/kernel/mars_net.h
+++ b/kernel/mars_net.h
@@ -125,6 +125,7 @@ extern bool mars_get_socket(struct mars_socket *msock);
 extern void mars_put_socket(struct mars_socket *msock);
 extern void mars_shutdown_socket(struct mars_socket *msock);
 extern bool mars_socket_is_alive(struct mars_socket *msock);
+extern long mars_socket_send_space_available(struct mars_socket *msock);
 
 extern int mars_send_raw(struct mars_socket *msock, const void *buf, int len, bool cork);
 extern int mars_recv_raw(struct mars_socket *msock, void *buf, int minlen, int maxlen);