[src/trunk]: src/sys/netinet6 Add comments describing parameter handling for ...

[gdt <gdt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c3e150c1e692
branches:  trunk
changeset: 780364:c3e150c1e692
user:      gdt <gdt%NetBSD.org@localhost>
date:      Sat Jul 21 14:52:40 2012 +0000

description:
Add comments describing parameter handling for ip6_insertfraghdr.

Depending on compiler options, this code can be involved in an
(apparently) spurious compiler warning.  However, it was not
immediately obvious the the compiler was wrong.

diffstat:

 sys/netinet6/ip6_output.c |  8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diffs (29 lines):

diff -r 12fb0f2e41c5 -r c3e150c1e692 sys/netinet6/ip6_output.c
--- a/sys/netinet6/ip6_output.c Sat Jul 21 12:30:55 2012 +0000
+++ b/sys/netinet6/ip6_output.c Sat Jul 21 14:52:40 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ip6_output.c,v 1.149 2012/06/25 15:28:40 christos Exp $        */
+/*     $NetBSD: ip6_output.c,v 1.150 2012/07/21 14:52:40 gdt Exp $     */
 /*     $KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $    */
 
 /*
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.149 2012/06/25 15:28:40 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.150 2012/07/21 14:52:40 gdt Exp $");
 
 #include "opt_inet.h"
 #include "opt_inet6.h"
@@ -1147,6 +1147,10 @@
 
 /*
  * Insert fragment header and copy unfragmentable header portions.
+ * 
+ * *frghdrp will not be read, and it is guaranteed that either an
+ * error is returned or that *frghdrp will point to space allocated
+ * for the fragment header.
  */
 static int
 ip6_insertfraghdr(struct mbuf *m0, struct mbuf *m, int hlen,