From fdd1b7f52a5a57cb4e0652ddd6cc77e019ca6b0a Mon Sep 17 00:00:00 2001
From: Andre Oppermann <andre@FreeBSD.org>
Date: Mon, 29 Oct 2012 12:14:57 +0000
Subject: [PATCH] Add logging for socket attach failures in sonewconn() during
 accept(2). Include the pointer to the PCB so it can be attributed to a
 particular application by corresponding it to "netstat -A" output.

MFC after:	2 weeks
---
 sys/kern/uipc_socket.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 1943c5dac0e2..e6b7bac93236 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -135,6 +135,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <sys/uio.h>
 #include <sys/jail.h>
+#include <sys/syslog.h>
 
 #include <net/vnet.h>
 
@@ -500,16 +501,24 @@ sonewconn(struct socket *head, int connstatus)
 	over = (head->so_qlen > 3 * head->so_qlimit / 2);
 	ACCEPT_UNLOCK();
 #ifdef REGRESSION
-	if (regression_sonewconn_earlytest && over)
+	if (regression_sonewconn_earlytest && over) {
 #else
-	if (over)
+	if (over) {
 #endif
+		log(LOG_DEBUG, "%s: pcb %p: Listen queue overflow: "
+		    "%i already in queue awaiting acceptance\n",
+		    __func__, head->so_pcb, over);
 		return (NULL);
+	}
 	VNET_ASSERT(head->so_vnet != NULL, ("%s:%d so_vnet is NULL, head=%p",
 	    __func__, __LINE__, head));
 	so = soalloc(head->so_vnet);
-	if (so == NULL)
+	if (so == NULL) {
+		log(LOG_DEBUG, "%s: pcb %p: New socket allocation failure: "
+		    "limit reached or out of memory\n",
+		    __func__, head->so_pcb);
 		return (NULL);
+	}
 	if ((head->so_options & SO_ACCEPTFILTER) != 0)
 		connstatus = 0;
 	so->so_head = head;
@@ -526,9 +535,16 @@ sonewconn(struct socket *head, int connstatus)
 	knlist_init_mtx(&so->so_rcv.sb_sel.si_note, SOCKBUF_MTX(&so->so_rcv));
 	knlist_init_mtx(&so->so_snd.sb_sel.si_note, SOCKBUF_MTX(&so->so_snd));
 	VNET_SO_ASSERT(head);
-	if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat) ||
-	    (*so->so_proto->pr_usrreqs->pru_attach)(so, 0, NULL)) {
+	if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
 		sodealloc(so);
+		log(LOG_DEBUG, "%s: pcb %p: soreserve() failed\n",
+		    __func__, head->so_pcb);
+		return (NULL);
+	}
+	if ((*so->so_proto->pr_usrreqs->pru_attach)(so, 0, NULL)) {
+		sodealloc(so);
+		log(LOG_DEBUG, "%s: pcb %p: pru_attach() failed\n",
+		    __func__, head->so_pcb);
 		return (NULL);
 	}
 	so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;