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

2 files changed, 6 insertions, 12 deletions

diff --git a/sys/netipsec/key.c b/sys/netipsec/key.c
index b9bcd59..a4e8a25 100644
--- a/sys/netipsec/key.c
+++ b/sys/netipsec/key.c
@@ -2153,8 +2153,7 @@ key_spddelete2(struct socket *so, struct mbuf *m,
 
 	MGETHDR(n, M_NOWAIT, MT_DATA);
 	if (n && len > MHLEN) {
-		MCLGET(n, M_NOWAIT);
-		if ((n->m_flags & M_EXT) == 0) {
+		if (!(MCLGET(n, M_NOWAIT))) {
 			m_freem(n);
 			n = NULL;
 		}
@@ -3496,8 +3495,7 @@ key_setsadbmsg(u_int8_t type, u_int16_t tlen, u_int8_t satype, u_int32_t seq,
 		return NULL;
 	MGETHDR(m, M_NOWAIT, MT_DATA);
 	if (m && len > MHLEN) {
-		MCLGET(m, M_NOWAIT);
-		if ((m->m_flags & M_EXT) == 0) {
+		if (!(MCLGET(m, M_NOWAIT))) {
 			m_freem(m);
 			m = NULL;
 		}
@@ -4694,8 +4692,7 @@ key_getspi(struct socket *so, struct mbuf *m, const struct sadb_msghdr *mhp)
 
 	MGETHDR(n, M_NOWAIT, MT_DATA);
 	if (len > MHLEN) {
-		MCLGET(n, M_NOWAIT);
-		if ((n->m_flags & M_EXT) == 0) {
+		if (!(MCLGET(n, M_NOWAIT))) {
 			m_freem(n);
 			n = NULL;
 		}
@@ -6628,8 +6625,7 @@ key_register(struct socket *so, struct mbuf *m, const struct sadb_msghdr *mhp)
 
 	MGETHDR(n, M_NOWAIT, MT_DATA);
 	if (len > MHLEN) {
-		MCLGET(n, M_NOWAIT);
-		if ((n->m_flags & M_EXT) == 0) {
+		if (!(MCLGET(n, M_NOWAIT))) {
 			m_freem(n);
 			n = NULL;
 		}
@@ -7187,8 +7183,7 @@ key_parse(struct mbuf *m, struct socket *so)
 
 		MGETHDR(n, M_NOWAIT, MT_DATA);
 		if (n && m->m_pkthdr.len > MHLEN) {
-			MCLGET(n, M_NOWAIT);
-			if ((n->m_flags & M_EXT) == 0) {
+			if (!(MCLGET(n, M_NOWAIT))) {
 				m_free(n);
 				n = NULL;
 			}
diff --git a/sys/netipsec/keysock.c b/sys/netipsec/keysock.c
index 6deea35..605d79c 100644
--- a/sys/netipsec/keysock.c
+++ b/sys/netipsec/keysock.c
@@ -223,8 +223,7 @@ key_sendup(struct socket *so, struct sadb_msg *msg, u_int len, int target)
 			n->m_len = MLEN;
 		}
 		if (tlen >= MCLBYTES) {	/*XXX better threshold? */
-			MCLGET(n, M_NOWAIT);
-			if ((n->m_flags & M_EXT) == 0) {
+			if (!(MCLGET(n, M_NOWAIT))) {
 				m_free(n);
 				m_freem(m);
 				PFKEYSTAT_INC(in_nomem);