Hide the unfortunate named sysctl kern.ipc.somaxconn from sysctl -a

output and replace it with a new visible sysctl kern.ipc.acceptqueue
of the same functionality.  It specifies the maximum length of the
accept queue on a listen socket.

The old kern.ipc.somaxconn remains available for reading and writing
for compatibility reasons so that existing programs, scripts and
configurations continue to work.  There no plans to ever remove the
orginal and now hidden kern.ipc.somaxconn.

2 files changed, 25 insertions, 5 deletions

diff --git a/lib/libc/sys/listen.2 b/lib/libc/sys/listen.2
index bd6abde..e09d1ca 100644
--- a/lib/libc/sys/listen.2
+++ b/lib/libc/sys/listen.2
@@ -28,7 +28,7 @@
 .\"	From: @(#)listen.2	8.2 (Berkeley) 12/11/93
 .\" $FreeBSD$
 .\"
-.Dd August 29, 2005
+.Dd October 20, 2012
 .Dt LISTEN 2
 .Os
 .Sh NAME
@@ -102,15 +102,15 @@ of service attacks are no longer necessary.
 The
 .Xr sysctl 3
 MIB variable
-.Va kern.ipc.somaxconn
+.Va kern.ipc.soacceptqueue
 specifies a hard limit on
 .Fa backlog ;
 if a value greater than
-.Va kern.ipc.somaxconn
+.Va kern.ipc.soacceptqueue
 or less than zero is specified,
 .Fa backlog
 is silently forced to
-.Va kern.ipc.somaxconn .
+.Va kern.ipc.soacceptqueue .
 .Sh INTERACTION WITH ACCEPT FILTERS
 When accept filtering is used on a socket, a second queue will
 be used to hold sockets that have connected, but have not yet
@@ -168,3 +168,17 @@ at run-time, and to use a negative
 .Fa backlog
 to request the maximum allowable value, was introduced in
 .Fx 2.2 .
+The
+.Va kern.ipc.somaxconn
+.Xr sysctl 3
+has been replaced with
+.Va kern.ipc.soacceptqueue
+in
+.Fx 10.0
+to prevent confusion its actual functionality.
+The original
+.Xr sysctl 3
+.Va kern.ipc.somaxconn
+is still available but hidden from a
+.Xr sysctl 3
+-a output so that existing applications and scripts continue to work.
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 6b5581f..a964cf2 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -185,6 +185,8 @@ MALLOC_DEFINE(M_PCB, "pcb", "protocol control block");
 /*
  * Limit on the number of connections in the listen queue waiting
  * for accept(2).
+ * NB: The orginal sysctl somaxconn is still available but hidden
+ * to prevent confusion about the actually purpose of this number.
  */
 static int somaxconn = SOMAXCONN;
 
@@ -205,9 +207,13 @@ sysctl_somaxconn(SYSCTL_HANDLER_ARGS)
 	somaxconn = val;
 	return (0);
 }
-SYSCTL_PROC(_kern_ipc, KIPC_SOMAXCONN, somaxconn, CTLTYPE_UINT | CTLFLAG_RW,
+SYSCTL_PROC(_kern_ipc, OID_AUTO, soacceptqueue, CTLTYPE_UINT | CTLFLAG_RW,
     0, sizeof(int), sysctl_somaxconn, "I",
     "Maximum listen socket pending connection accept queue size");
+SYSCTL_PROC(_kern_ipc, KIPC_SOMAXCONN, somaxconn,
+    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_SKIP,
+    0, sizeof(int), sysctl_somaxconn, "I",
+    "Maximum listen socket pending connection accept queue size (compat)");
 
 static int numopensockets;
 SYSCTL_INT(_kern_ipc, OID_AUTO, numopensockets, CTLFLAG_RD,