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/dev/my/if_my.c b/sys/dev/my/if_my.c
index e94e9ab..e2430c1 100644
--- a/sys/dev/my/if_my.c
+++ b/sys/dev/my/if_my.c
@@ -1085,8 +1085,7 @@ my_newbuf(struct my_softc * sc, struct my_chain_onefrag * c)
 		    "no memory for rx list -- packet dropped!\n");
 		return (ENOBUFS);
 	}
-	MCLGET(m_new, M_NOWAIT);
-	if (!(m_new->m_flags & M_EXT)) {
+	if (!(MCLGET(m_new, M_NOWAIT))) {
 		device_printf(sc->my_dev,
 		    "no memory for rx list -- packet dropped!\n");
 		m_freem(m_new);
@@ -1352,8 +1351,7 @@ my_encap(struct my_softc * sc, struct my_chain * c, struct mbuf * m_head)
 		return (1);
 	}
 	if (m_head->m_pkthdr.len > MHLEN) {
-		MCLGET(m_new, M_NOWAIT);
-		if (!(m_new->m_flags & M_EXT)) {
+		if (!(MCLGET(m_new, M_NOWAIT))) {
 			m_freem(m_new);
 			device_printf(sc->my_dev, "no memory for tx list");
 			return (1);