svn commit: r281951 - stable/10/sys/sys

[Garrett Cooper]

Author: ngie
Date: Fri Apr 24 21:38:18 2015
New Revision: 281951
URL: https://svnweb.freebsd.org/changeset/base/281951

Log:
  Backport MHSIZE/MPKTHSIZE equivalents from head
  
  These macros are equivalent to the ones on head, except they are only exposed
  when _KERNEL is defined, i.e. to kernel code, whereas the code on head is exposed
  to userland as well
  
  This is for improved forwards compatibility with mbuf(9) macros in head at r277203+,
  and is required for a clean MFC of r279393
  
  This is a direct commit to stable/10
  
  MFC after: 3 days
  Differential Revision: https://reviews.freebsd.org/D2126
  Reviewed by: glebius, rwatson
  Sponsored by: EMC / Isilon Storage Division

Modified:
  stable/10/sys/sys/mbuf.h

Modified: stable/10/sys/sys/mbuf.h
==============================================================================
--- stable/10/sys/sys/mbuf.h	Fri Apr 24 21:05:29 2015	(r281950)
+++ stable/10/sys/sys/mbuf.h	Fri Apr 24 21:38:18 2015	(r281951)
@@ -206,6 +206,16 @@ struct mbuf {
 #define	m_pktdat	M_dat.MH.MH_dat.MH_databuf
 #define	m_dat		M_dat.M_databuf
 
+/* 
+ * NOTE: forwards compatibility definitions for mbuf(9)
+ *
+ * These aren't 1:1 with the macros in r277203; in particular they're exposed
+ * to both userland and kernel, whereas this is exposed to just _KERNEL -- to
+ * avoid disruption with existing KBI/KPIs
+ */
+#define	MHSIZE		offsetof(struct mbuf, m_dat)
+#define	MPKTHSIZE	offsetof(struct mbuf, m_pktdat)
+
 /*
  * mbuf flags of global significance and layer crossing.
  * Those of only protocol/layer specific significance are to be mapped