From 7cc13edc139108bb527b692f0548dce6bc648572 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Sun, 5 Nov 2006 23:52:13 -0800
Subject: [PATCH] sysctl: implement CTL_UNNUMBERED

This patch takes the CTL_UNNUMBERD concept from NFS and makes it available to
all new sysctl users.

At the same time the sysctl binary interface maintenance documentation is
updated to mention and to describe what is needed to successfully maintain the
sysctl binary interface.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 include/linux/sysctl.h | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

(limited to 'include')

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index c184732..d98562f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -6,10 +6,17 @@
  ****************************************************************
  ****************************************************************
  **
+ **  WARNING:
  **  The values in this file are exported to user space via 
- **  the sysctl() binary interface.  However this interface
- **  is unstable and deprecated and will be removed in the future. 
- **  For a stable interface use /proc/sys.
+ **  the sysctl() binary interface.  Do *NOT* change the
+ **  numbering of any existing values here, and do not change
+ **  any numbers within any one set of values.  If you have to
+ **  have to redefine an existing interface, use a new number for it.
+ **  The kernel will then return -ENOTDIR to any application using
+ **  the old binary interface.
+ **
+ **  For new interfaces unless you really need a binary number
+ **  please use CTL_UNNUMBERED.
  **
  ****************************************************************
  ****************************************************************
@@ -48,6 +55,7 @@ struct __sysctl_args {
 #ifdef __KERNEL__
 #define CTL_ANY		-1	/* Matches any name */
 #define CTL_NONE	0
+#define CTL_UNNUMBERED	CTL_NONE	/* sysctl without a binary number */
 #endif
 
 enum
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