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From: Mark Johnston <markj@FreeBSD.org>
Date: Thu, 12 Mar 2015 01:05:54 +0000 (UTC)
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Subject: svn commit: r279896 - head/share/man/man9
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Author: markj
Date: Thu Mar 12 01:05:54 2015
New Revision: 279896
URL: https://svnweb.freebsd.org/changeset/base/279896

Log:
  Document m_collapse().
  
  Reported by:	kmacy
  Reviewed by:	kmacy
  MFC after:	1 week
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/share/man/man9/mbuf.9

Modified: head/share/man/man9/mbuf.9
==============================================================================
--- head/share/man/man9/mbuf.9	Thu Mar 12 01:03:04 2015	(r279895)
+++ head/share/man/man9/mbuf.9	Thu Mar 12 01:05:54 2015	(r279896)
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 5, 2015
+.Dd March 11, 2015
 .Dt MBUF 9
 .Os
 .\"
@@ -141,6 +141,8 @@
 .Ft struct mbuf *
 .Fn m_defrag "struct mbuf *m0" "int how"
 .Ft struct mbuf *
+.Fn m_collapse "struct mbuf *m0" "int how" "int maxfrags"
+.Ft struct mbuf *
 .Fn m_unshare "struct mbuf *m0" "int how"
 .\"
 .Sh DESCRIPTION
@@ -983,6 +985,20 @@ depending on the caller's preference.
 This function is especially useful in network drivers, where
 certain long mbuf chains must be shortened before being added
 to TX descriptor lists.
+.It Fn m_collapse m0 how maxfrags
+Defragment an mbuf chain, returning a chain of at most
+.Fa maxfrags
+mbufs and clusters.
+If allocation fails or the chain cannot be collapsed as requested,
+.Dv NULL
+will be returned, with the original chain possibly modified.
+As with
+.Fn m_defrag ,
+.Fa how
+should be one of
+.Dv M_WAITOK
+or
+.Dv M_NOWAIT .
 .It Fn m_unshare m0 how
 Create a version of the specified mbuf chain whose
 contents can be safely modified without affecting other users.