netmap: manually backport multiple fixes

o Restore netmap emulation mode to working order, including
  fixing the destructor panics on detach.
o Omit pipe additions to these fixes, likely problematic for
  Suricata to pass traffic like it does on 11.0 without this
  patch.
o Allow to build the module without errors in the tree.

Many thanks to Vincenzo Maffione for assistance and review!  :)

From b497fe34fd275da6b850bf271f510d02b888b8bc Mon Sep 17 00:00:00 2001
From: Giuseppe Lettieri <g.lettieri@iet.unipi.it>
Date: Thu, 2 Jun 2016 00:21:40 +0200
Subject: [PATCH] allocate only the rings requested by the user

From 09936864fa5b67b82ef4a9907819b7018e9a38f2 Mon Sep 17 00:00:00 2001
From: Giuseppe Lettieri <g.lettieri@iet.unipi.it>
Date: Wed, 20 Jul 2016 20:35:12 +0000
Subject: [PATCH] freebsd: fix const-related warning

From ab90c6c10224fefbb6a6c6e0b92e6ba80e5b694d Mon Sep 17 00:00:00 2001
From: Vincenzo Maffione <v.maffione@gmail.com>
Date: Wed, 28 Sep 2016 18:39:55 +0200
Subject: [PATCH] freebsd: generic: change mbuf allocation management

From fe811e11b2c37fc274a1134e1c10b2f6ada1a91c Mon Sep 17 00:00:00 2001
From: Vincenzo Maffione <v.maffione@gmail.com>
Date: Thu, 29 Sep 2016 08:54:52 +0200
Subject: [PATCH] freebsd: generic: call m_extadd() only once for each mbuf

sys/dev/netmap/netmap.c

@@ -908,6 +908,10 @@ netmap_do_unregif(struct netmap_priv_d *priv)
 	na->active_fds--;
 	/* release exclusive use if it was requested on regif */
 	netmap_rel_exclusive(priv);
+
+	/* delete rings and buffers that are no longer needed */
+	netmap_mem_rings_delete(na);
+
 	if (na->active_fds <= 0) {	/* last instance */
 
 		if (netmap_verbose)
@@ -939,8 +943,6 @@ netmap_do_unregif(struct netmap_priv_d *priv)
 		 * XXX The wake up now must happen during *_down(), when
 		 * we order all activities to stop. -gl
 		 */
-		/* delete rings and buffers */
-		netmap_mem_rings_delete(na);
 		na->nm_krings_delete(na);
 	}
 	/* possibily decrement counter of tx_si/rx_si users */
@@ -1948,7 +1950,7 @@ netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
 	if (na->active_fds == 0) {
 		/*
 		 * If this is the first registration of the adapter,
-		 * also create the netmap rings and their in-kernel view,
+		 * create the  in-kernel view of the netmap rings,
 		 * the netmap krings.
 		 */
 
@@ -1959,25 +1961,25 @@ netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
 		error = na->nm_krings_create(na);
 		if (error)
 			goto err_drop_mem;
-
-		/* create all missing netmap rings */
-		error = netmap_mem_rings_create(na);
-		if (error)
-			goto err_del_krings;
 	}
 
-	/* now the kring must exist and we can check whether some
+	/* now the krings must exist and we can check whether some
 	 * previous bind has exclusive ownership on them
 	 */
 	error = netmap_get_exclusive(priv);
 	if (error)
-		goto err_del_rings;
+		goto err_del_krings;
+
+	/* create all needed missing netmap rings */
+	error = netmap_mem_rings_create(na);
+	if (error)
+		goto err_rel_excl;
 
 	/* in all cases, create a new netmap if */
 	nifp = netmap_mem_if_new(na);
 	if (nifp == NULL) {
 		error = ENOMEM;
-		goto err_rel_excl;
+		goto err_del_rings;
 	}
 
 	na->active_fds++;
@@ -2010,8 +2012,7 @@ netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
 err_rel_excl:
 	netmap_rel_exclusive(priv);
 err_del_rings:
-	if (na->active_fds == 0)
-		netmap_mem_rings_delete(na);
+	netmap_mem_rings_delete(na);
 err_del_krings:
 	if (na->active_fds == 0)
 		na->nm_krings_delete(na);

sys/dev/netmap/netmap_freebsd.c

@@ -224,22 +224,9 @@ generic_xmit_frame(struct ifnet *ifp, struct mbuf *m,
 	 * (and eventually, just reference the netmap buffer)
 	 */
 
-	if (GET_MBUF_REFCNT(m) != 1) {
-		D("invalid refcnt %d for %p",
-			GET_MBUF_REFCNT(m), m);
-		panic("in generic_xmit_frame");
-	}
-	// XXX the ext_size check is unnecessary if we link the netmap buf
-	if (m->m_ext.ext_size < len) {
-		RD(5, "size %d < len %d", m->m_ext.ext_size, len);
-		len = m->m_ext.ext_size;
-	}
-	if (0) { /* XXX seems to have negligible benefits */
-		m->m_ext.ext_buf = m->m_data = addr;
-	} else {
-		bcopy(addr, m->m_data, len);
-	}
-	m->m_len = m->m_pkthdr.len = len;
+	m->m_ext.ext_buf = m->m_data = addr;
+	m->m_ext.ext_size = m->m_len = m->m_pkthdr.len = len;
+
 	// inc refcount. All ours, we could skip the atomic
 	atomic_fetchadd_int(PNT_MBUF_REFCNT(m), 1);
 	M_HASHTYPE_SET(m, M_HASHTYPE_OPAQUE);

sys/dev/netmap/netmap_generic.c

@@ -109,34 +109,30 @@ __FBSDID("$FreeBSD$");
  */
 #define SET_MBUF_DESTRUCTOR(m, fn)	do {		\
 	(m)->m_ext.ext_free = (void *)fn;	\
-	(m)->m_ext.ext_type = EXT_EXTREF;	\
 } while (0)
 
-static void
-netmap_default_mbuf_destructor(struct mbuf *m)
-{
-	/* restore original mbuf */
-	m->m_ext.ext_buf = m->m_data = m->m_ext.ext_arg1;
-	m->m_ext.ext_arg1 = NULL;
-	m->m_ext.ext_type = EXT_PACKET;
-	m->m_ext.ext_free = NULL;
-	if (GET_MBUF_REFCNT(m) == 0)
-		SET_MBUF_REFCNT(m, 1);
-	uma_zfree(zone_pack, m);
-}
+#if __FreeBSD_version < 1100000
+static int void_mbuf_dtor(struct mbuf *m, void *arg1, void *arg2) { return 0; }
+#else
+static void void_mbuf_dtor(struct mbuf *m, void *arg1, void *arg2) { }
+#endif
 
 static inline struct mbuf *
 netmap_get_mbuf(int len)
 {
 	struct mbuf *m;
-	m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
-	if (m) {
-		m->m_flags |= M_NOFREE;	/* XXXNP: Almost certainly incorrect. */
-		m->m_ext.ext_arg1 = m->m_ext.ext_buf; // XXX save
-		m->m_ext.ext_free = (void *)netmap_default_mbuf_destructor;
-		m->m_ext.ext_type = EXT_EXTREF;
-		ND(5, "create m %p refcnt %d", m, GET_MBUF_REFCNT(m));
+
+	m = m_gethdr(M_NOWAIT, MT_DATA);
+	if (m == NULL) {
+		return m;
 	}
+
+	m_extadd(m, NULL /* buf */, 0 /* size */, void_mbuf_dtor, NULL, NULL, 0, EXT_NET_DRV
+#if __FreeBSD_version < 1100000
+		, M_NOWAIT
+#endif
+	);
+
 	return m;
 }
 
@@ -412,11 +408,6 @@ static void
 generic_mbuf_destructor(struct mbuf *m)
 {
 	netmap_generic_irq(MBUF_IFP(m), MBUF_TXQ(m), NULL);
-#ifdef __FreeBSD__
-	if (netmap_verbose)
-		RD(5, "Tx irq (%p) queue %d index %d" , m, MBUF_TXQ(m), (int)(uintptr_t)m->m_ext.ext_arg1);
-	netmap_default_mbuf_destructor(m);
-#endif /* __FreeBSD__ */
 	IFRATE(rate_ctx.new.txirq++);
 }
 

sys/dev/netmap/netmap_kern.h

@@ -97,9 +97,9 @@ struct netmap_adapter *netmap_getna(if_t ifp);
 #endif
 
 #if __FreeBSD_version >= 1100027
-#define GET_MBUF_REFCNT(m)      ((m)->m_ext.ext_cnt ? *((m)->m_ext.ext_cnt) : -1)
-#define SET_MBUF_REFCNT(m, x)   *((m)->m_ext.ext_cnt) = x
-#define PNT_MBUF_REFCNT(m)      ((m)->m_ext.ext_cnt)
+#define GET_MBUF_REFCNT(m)	((m)->m_ext.ext_count)
+#define SET_MBUF_REFCNT(m, x)   (m)->m_ext.ext_count = x
+#define PNT_MBUF_REFCNT(m)      &((m)->m_ext.ext_count)
 #else
 #define GET_MBUF_REFCNT(m)      ((m)->m_ext.ref_cnt ? *((m)->m_ext.ref_cnt) : -1)
 #define SET_MBUF_REFCNT(m, x)   *((m)->m_ext.ref_cnt) = x

sys/dev/netmap/netmap_mem2.c

@@ -1421,8 +1421,11 @@ netmap_free_rings(struct netmap_adapter *na)
 			struct netmap_kring *kring = &NMR(na, t)[i];
 			struct netmap_ring *ring = kring->ring;
 
-			if (ring == NULL)
+			if (ring == NULL) {
+				ND("skipping ring %s (ring %p, users %d)",
+						kring->name, ring, kring->users);
 				continue;
+			}
 			netmap_free_bufs(na->nm_mem, ring->slot, kring->nkr_num_slots);
 			netmap_ring_free(na->nm_mem, ring);
 			kring->ring = NULL;
@@ -1453,8 +1456,9 @@ netmap_mem2_rings_create(struct netmap_adapter *na)
 			u_int len, ndesc;
 
 			if (ring) {
-				ND("%s already created", kring->name);
-				continue; /* already created by somebody else */
+				/* uneeded, or already created by somebody else */
+				ND("skipping ring %s", kring->name);
+				continue;
 			}
 			ndesc = kring->nkr_num_slots;
 			len = sizeof(struct netmap_ring) +
@@ -1569,10 +1573,22 @@ netmap_mem2_if_new(struct netmap_adapter *na)
 	 */
 	base = netmap_if_offset(na->nm_mem, nifp);
 	for (i = 0; i < n[NR_TX]; i++) {
+		if (na->tx_rings[i].ring == NULL) {
+			// XXX maybe use the offset of an error ring,
+			// like we do for buffers?
+			*(ssize_t *)(uintptr_t)&nifp->ring_ofs[i] = 0;
+			continue;
+		}
 		*(ssize_t *)(uintptr_t)&nifp->ring_ofs[i] =
 			netmap_ring_offset(na->nm_mem, na->tx_rings[i].ring) - base;
 	}
 	for (i = 0; i < n[NR_RX]; i++) {
+		if (na->rx_rings[i].ring == NULL) {
+			// XXX maybe use the offset of an error ring,
+			// like we do for buffers?
+			*(ssize_t *)(uintptr_t)&nifp->ring_ofs[i+n[NR_TX]] = 0;
+			continue;
+		}
 		*(ssize_t *)(uintptr_t)&nifp->ring_ofs[i+n[NR_TX]] =
 			netmap_ring_offset(na->nm_mem, na->rx_rings[i].ring) - base;
 	}

sys/modules/netmap/Makefile

@@ -17,5 +17,6 @@ SRCS	+= netmap_freebsd.c
 SRCS	+= netmap_offloadings.c
 SRCS	+= netmap_pipe.c
 SRCS	+= netmap_monitor.c
+SRCS	+= opt_inet.h opt_inet6.h
 
 .include <bsd.kmod.mk>