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

5 files changed, 8 insertions, 16 deletions

diff --git a/sys/netgraph/atm/ngatmbase.c b/sys/netgraph/atm/ngatmbase.c
index c5b0ced..a5f1027 100644
--- a/sys/netgraph/atm/ngatmbase.c
+++ b/sys/netgraph/atm/ngatmbase.c
@@ -151,8 +151,7 @@ uni_msg_pack_mbuf(struct uni_msg *msg, void *hdr, size_t hdrlen)
 
 	} else {
 		if ((n = uni_msg_len(msg)) > MHLEN) {
-			MCLGET(m0, M_NOWAIT);
-			if (!(m0->m_flags & M_EXT))
+			if (!(MCLGET(m0, M_NOWAIT)))
 				goto drop;
 			if (n > MCLBYTES)
 				n = MCLBYTES;
@@ -173,8 +172,7 @@ uni_msg_pack_mbuf(struct uni_msg *msg, void *hdr, size_t hdrlen)
 		last = m;
 
 		if (n > MLEN) {
-			MCLGET(m, M_NOWAIT);
-			if (!(m->m_flags & M_EXT))
+			if (!(MCLGET(m, M_NOWAIT)))
 				goto drop;
 			if (n > MCLBYTES)
 				n = MCLBYTES;
diff --git a/sys/netgraph/atm/sscop/ng_sscop_cust.h b/sys/netgraph/atm/sscop/ng_sscop_cust.h
index a1d839a..2c4e0de 100644
--- a/sys/netgraph/atm/sscop/ng_sscop_cust.h
+++ b/sys/netgraph/atm/sscop/ng_sscop_cust.h
@@ -327,8 +327,7 @@ ng_sscop_mbuf_alloc(size_t n)						\
 		m->m_len = 0;						\
 		m->m_pkthdr.len = 0;					\
 		if (n > MHLEN) {					\
-			MCLGET(m, M_NOWAIT);				\
-			if (!(m->m_flags & M_EXT)){			\
+			if (!(MCLGET(m, M_NOWAIT))){			\
 				m_free(m);				\
 				m = NULL;				\
 			}						\
diff --git a/sys/netgraph/bluetooth/drivers/bt3c/ng_bt3c_pccard.c b/sys/netgraph/bluetooth/drivers/bt3c/ng_bt3c_pccard.c
index 9b174bb..d7cff74 100644
--- a/sys/netgraph/bluetooth/drivers/bt3c/ng_bt3c_pccard.c
+++ b/sys/netgraph/bluetooth/drivers/bt3c/ng_bt3c_pccard.c
@@ -814,8 +814,7 @@ bt3c_receive(bt3c_softc_p sc)
 				break; /* XXX lost of sync */
 			}
 
-			MCLGET(sc->m, M_NOWAIT);
-			if (!(sc->m->m_flags & M_EXT)) {
+			if (!(MCLGET(sc->m, M_NOWAIT))) {
 				NG_FREE_M(sc->m);
 
 				NG_BT3C_ERR(sc->dev, "Could not get cluster\n");
diff --git a/sys/netgraph/bluetooth/drivers/ubt/ng_ubt.c b/sys/netgraph/bluetooth/drivers/ubt/ng_ubt.c
index 2488d06..f34c708 100644
--- a/sys/netgraph/bluetooth/drivers/ubt/ng_ubt.c
+++ b/sys/netgraph/bluetooth/drivers/ubt/ng_ubt.c
@@ -816,8 +816,7 @@ ubt_intr_read_callback(struct usb_xfer *xfer, usb_error_t error)
 			goto submit_next;
 		}
 
-		MCLGET(m, M_NOWAIT);
-		if (!(m->m_flags & M_EXT)) {
+		if (!(MCLGET(m, M_NOWAIT))) {
 			UBT_STAT_IERROR(sc);
 			goto submit_next;
 		}
@@ -916,8 +915,7 @@ ubt_bulk_read_callback(struct usb_xfer *xfer, usb_error_t error)
 			goto submit_next;
 		}
 
-		MCLGET(m, M_NOWAIT);
-		if (!(m->m_flags & M_EXT)) {
+		if (!(MCLGET(m, M_NOWAIT))) {
 			UBT_STAT_IERROR(sc);
 			goto submit_next;
 		}
@@ -1126,8 +1124,7 @@ ubt_isoc_read_one_frame(struct usb_xfer *xfer, int frame_no)
 				return (-1);	/* XXX out of sync! */
 			}
 
-			MCLGET(m, M_NOWAIT);
-			if (!(m->m_flags & M_EXT)) {
+			if (!(MCLGET(m, M_NOWAIT))) {
 				UBT_STAT_IERROR(sc);
 				NG_FREE_M(m);
 				return (-1);	/* XXX out of sync! */
diff --git a/sys/netgraph/ng_vjc.c b/sys/netgraph/ng_vjc.c
index e1b76b5..e689a10 100644
--- a/sys/netgraph/ng_vjc.c
+++ b/sys/netgraph/ng_vjc.c
@@ -484,8 +484,7 @@ ng_vjc_rcvdata(hook_p hook, item_p item)
 		hm->m_len = 0;
 		hm->m_pkthdr.rcvif = NULL;
 		if (hlen > MHLEN) {		/* unlikely, but can happen */
-			MCLGET(hm, M_NOWAIT);
-			if ((hm->m_flags & M_EXT) == 0) {
+			if (!(MCLGET(hm, M_NOWAIT))) {
 				m_freem(hm);
 				priv->slc.sls_errorin++;
 				NG_FREE_M(m);