In order to reduce use of M_EXT outside of the mbuf allocator and

socket-buffer implementations, introduce a return value for MCLGET()
(and m_cljget() that underlies it) to allow the caller to avoid testing
M_EXT itself.  Update all callers to use the return value.

With this change, very few network device drivers remain aware of
M_EXT; the primary exceptions lie in mbuf-chain pretty printers for
debugging, and in a few cases, custom mbuf and cluster allocation
implementations.

NB: This is a difficult-to-test change as it touches many drivers for
which I don't have physical devices.  Instead we've gone for intensive
review, but further post-commit review would definitely be appreciated
to spot errors where changes could not easily be made mechanically,
but were largely mechanical in nature.

Differential Revision:	https://reviews.freebsd.org/D1440
Reviewed by:	adrian, bz, gnn
Sponsored by:	EMC / Isilon Storage Division

1 files changed, 2 insertions, 4 deletions

diff --git a/sys/contrib/ipfilter/netinet/ip_fil_freebsd.c b/sys/contrib/ipfilter/netinet/ip_fil_freebsd.c
index 8f8cb08..5515561 100644
--- a/sys/contrib/ipfilter/netinet/ip_fil_freebsd.c
+++ b/sys/contrib/ipfilter/netinet/ip_fil_freebsd.c
@@ -386,8 +386,7 @@ ipf_send_reset(fin)
 	if (m == NULL)
 		return -1;
 	if (sizeof(*tcp2) + hlen > MLEN) {
-		MCLGET(m, M_NOWAIT);
-		if ((m->m_flags & M_EXT) == 0) {
+		if (!(MCLGET(m, M_NOWAIT))) {
 			FREE_MB_T(m);
 			return -1;
 		}
@@ -610,8 +609,7 @@ ipf_send_icmp_err(type, fin, dst)
 			code = icmptoicmp6unreach[code];
 
 		if (iclen + max_linkhdr + fin->fin_plen > avail) {
-			MCLGET(m, M_NOWAIT);
-			if ((m->m_flags & M_EXT) == 0) {
+			if (!(MCLGET(m, M_NOWAIT))) {
 				FREE_MB_T(m);
 				return -1;
 			}