From 3b4a84e75709c242d486ad3349fbeb24bf3dce9f Mon Sep 17 00:00:00 2001
From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Tue, 12 Mar 2013 12:15:24 +0000
Subject: [PATCH] In kern_sendfile() use m_extadd() instead of MEXTADD() macro,
 supplying appropriate wait argument and checking return value. Before this
 change m_extadd() could fail, and kern_sendfile() ignored that.

Sponsored by:	Nginx, Inc.
---
 sys/kern/uipc_syscalls.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sys/kern/uipc_syscalls.c b/sys/kern/uipc_syscalls.c
index a2623067bd4..4827cab53d6 100644
--- a/sys/kern/uipc_syscalls.c
+++ b/sys/kern/uipc_syscalls.c
@@ -2222,8 +2222,14 @@ retry_space:
 				sf_buf_mext((void *)sf_buf_kva(sf), sf);
 				break;
 			}
-			MEXTADD(m0, sf_buf_kva(sf), PAGE_SIZE, sf_buf_mext,
-			    sfs, sf, M_RDONLY, EXT_SFBUF);
+			if (m_extadd(m0, (caddr_t )sf_buf_kva(sf), PAGE_SIZE,
+			    sf_buf_mext, sfs, sf, M_RDONLY, EXT_SFBUF,
+			    (mnw ? M_NOWAIT : M_WAITOK)) != 0) {
+				error = (mnw ? EAGAIN : ENOBUFS);
+				sf_buf_mext((void *)sf_buf_kva(sf), sf);
+				m_freem(m0);
+				break;
+			}
 			m0->m_data = (char *)sf_buf_kva(sf) + pgoff;
 			m0->m_len = xfsize;