better handling of netmap emulation over standard device drivers:

plug a potential mbuf leak, and detect bogus drivers that
return ENOBUFS even when the packet has been queued.

MFC after:	3 days

2 files changed, 83 insertions, 29 deletions

diff --git a/sys/dev/netmap/netmap_freebsd.c b/sys/dev/netmap/netmap_freebsd.c
index 9eecf85..6101045 100644
--- a/sys/dev/netmap/netmap_freebsd.c
+++ b/sys/dev/netmap/netmap_freebsd.c
@@ -61,7 +61,8 @@
 
 /* ======================== FREEBSD-SPECIFIC ROUTINES ================== */
 
-rawsum_t nm_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum)
+rawsum_t
+nm_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum)
 {
 	/* TODO XXX please use the FreeBSD implementation for this. */
 	uint16_t *words = (uint16_t *)data;
@@ -80,7 +81,8 @@ rawsum_t nm_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum)
 /* Fold a raw checksum: 'cur_sum' is in host byte order, while the
  * return value is in network byte order.
  */
-uint16_t nm_csum_fold(rawsum_t cur_sum)
+uint16_t
+nm_csum_fold(rawsum_t cur_sum)
 {
 	/* TODO XXX please use the FreeBSD implementation for this. */
 	while (cur_sum >> 16)
@@ -89,7 +91,8 @@ uint16_t nm_csum_fold(rawsum_t cur_sum)
 	return htobe16((~cur_sum) & 0xFFFF);
 }
 
-uint16_t nm_csum_ipv4(struct nm_iphdr *iph)
+uint16_t
+nm_csum_ipv4(struct nm_iphdr *iph)
 {
 #if 0
 	return in_cksum_hdr((void *)iph);
@@ -98,7 +101,8 @@ uint16_t nm_csum_ipv4(struct nm_iphdr *iph)
 #endif
 }
 
-void nm_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
+void
+nm_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
 					size_t datalen, uint16_t *check)
 {
 #ifdef INET
@@ -120,7 +124,8 @@ void nm_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
 #endif
 }
 
-void nm_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
+void
+nm_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
 					size_t datalen, uint16_t *check)
 {
 #ifdef INET6
@@ -143,7 +148,8 @@ void nm_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
 int
 netmap_catch_rx(struct netmap_adapter *na, int intercept)
 {
-	struct netmap_generic_adapter *gna = (struct netmap_generic_adapter *)na;
+	struct netmap_generic_adapter *gna =
+		(struct netmap_generic_adapter *)na;
 	struct ifnet *ifp = na->ifp;
 
 	if (intercept) {
@@ -209,11 +215,29 @@ generic_xmit_frame(struct ifnet *ifp, struct mbuf *m,
 {
 	int ret;
 
-	m->m_len = m->m_pkthdr.len = 0;
+	/*
+	 * The mbuf should be a cluster from our special pool,
+	 * so we do not need to do an m_copyback but just copy
+	 * (and eventually, just reference the netmap buffer)
+	 */
 
-	// copy data to the mbuf
-	m_copyback(m, 0, len, addr);
-	// inc refcount. We are alone, so we can skip the atomic
+	if (*m->m_ext.ref_cnt != 1) {
+		D("invalid refcnt %d for %p",
+			*m->m_ext.ref_cnt, 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;
+	// inc refcount. All ours, we could skip the atomic
 	atomic_fetchadd_int(m->m_ext.ref_cnt, 1);
 	m->m_flags |= M_FLOWID;
 	m->m_pkthdr.flowid = ring_nr;
@@ -238,7 +262,7 @@ netmap_getna(if_t ifp)
 int
 generic_find_num_desc(struct ifnet *ifp, unsigned int *tx, unsigned int *rx)
 {
-	D("called");
+	D("called, in tx %d rx %d", *tx, *rx);
 	return 0;
 }
 
@@ -246,13 +270,14 @@ generic_find_num_desc(struct ifnet *ifp, unsigned int *tx, unsigned int *rx)
 void
 generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq)
 {
-	D("called");
+	D("called, in txq %d rxq %d", *txq, *rxq);
 	*txq = netmap_generic_rings;
 	*rxq = netmap_generic_rings;
 }
 
 
-void netmap_mitigation_init(struct nm_generic_mit *mit, struct netmap_adapter *na)
+void
+netmap_mitigation_init(struct nm_generic_mit *mit, struct netmap_adapter *na)
 {
 	ND("called");
 	mit->mit_pending = 0;
@@ -260,26 +285,30 @@ void netmap_mitigation_init(struct nm_generic_mit *mit, struct netmap_adapter *n
 }
 
 
-void netmap_mitigation_start(struct nm_generic_mit *mit)
+void
+netmap_mitigation_start(struct nm_generic_mit *mit)
 {
 	ND("called");
 }
 
 
-void netmap_mitigation_restart(struct nm_generic_mit *mit)
+void
+netmap_mitigation_restart(struct nm_generic_mit *mit)
 {
 	ND("called");
 }
 
 
-int netmap_mitigation_active(struct nm_generic_mit *mit)
+int
+netmap_mitigation_active(struct nm_generic_mit *mit)
 {
 	ND("called");
 	return 0;
 }
 
 
-void netmap_mitigation_cleanup(struct nm_generic_mit *mit)
+void
+netmap_mitigation_cleanup(struct nm_generic_mit *mit)
 {
 	ND("called");
 }
diff --git a/sys/dev/netmap/netmap_generic.c b/sys/dev/netmap/netmap_generic.c
index b67f6fc..ef8a8f3 100644
--- a/sys/dev/netmap/netmap_generic.c
+++ b/sys/dev/netmap/netmap_generic.c
@@ -81,8 +81,8 @@ __FBSDID("$FreeBSD$");
 #include <dev/netmap/netmap_kern.h>
 #include <dev/netmap/netmap_mem2.h>
 
-#define rtnl_lock()	ND("rtnl_lock called");
-#define rtnl_unlock()	ND("rtnl_unlock called");
+#define rtnl_lock()	ND("rtnl_lock called")
+#define rtnl_unlock()	ND("rtnl_unlock called")
 #define MBUF_TXQ(m)	((m)->m_pkthdr.flowid)
 #define MBUF_RXQ(m)	((m)->m_pkthdr.flowid)
 #define smp_mb()
@@ -101,7 +101,6 @@ __FBSDID("$FreeBSD$");
 /*
  * mbuf wrappers
  */
-#define netmap_get_mbuf(len) m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR|M_NOFREE)
 
 /* mbuf destructor, also need to change the type to EXT_EXTREF,
  * add an M_NOFREE flag, and then clear the flag and
@@ -113,6 +112,32 @@ __FBSDID("$FreeBSD$");
 	(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 (*(m->m_ext.ref_cnt) == 0)
+		*(m->m_ext.ref_cnt) = 1;
+	uma_zfree(zone_pack, m);
+} 
+
+static inline struct mbuf * 
+netmap_get_mbuf(int len) 
+{ 
+	struct mbuf *m;
+	m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR | M_NOFREE);
+	if (m) {
+		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, *m->m_ext.ref_cnt);
+	}
+	return m;
+} 
 
 #define GET_MBUF_REFCNT(m)	((m)->m_ext.ref_cnt ? *(m)->m_ext.ref_cnt : -1)
 
@@ -230,7 +255,7 @@ generic_netmap_register(struct netmap_adapter *na, int enable)
 #endif /* REG_RESET */
 
 	if (enable) { /* Enable netmap mode. */
-		/* Init the mitigation support. */
+		/* Init the mitigation support on all the rx queues. */
 		gna->mit = malloc(na->num_rx_rings * sizeof(struct nm_generic_mit),
 					M_DEVBUF, M_NOWAIT | M_ZERO);
 		if (!gna->mit) {
@@ -380,15 +405,11 @@ out:
 static void
 generic_mbuf_destructor(struct mbuf *m)
 {
-	if (netmap_verbose)
-		D("Tx irq (%p) queue %d", m, MBUF_TXQ(m));
 	netmap_generic_irq(MBUF_IFP(m), MBUF_TXQ(m), NULL);
 #ifdef __FreeBSD__
-	m->m_ext.ext_type = EXT_PACKET;
-	m->m_ext.ext_free = NULL;
-	if (*(m->m_ext.ref_cnt) == 0)
-		*(m->m_ext.ref_cnt) = 1;
-	uma_zfree(zone_pack, m);
+	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++);
 }
@@ -478,12 +499,12 @@ generic_set_tx_event(struct netmap_kring *kring, u_int hwcur)
 	e = generic_tx_event_middle(kring, hwcur);
 
 	m = kring->tx_pool[e];
+	ND(5, "Request Event at %d mbuf %p refcnt %d", e, m, m ? GET_MBUF_REFCNT(m) : -2 );
 	if (m == NULL) {
 		/* This can happen if there is already an event on the netmap
 		   slot 'e': There is nothing to do. */
 		return;
 	}
-	ND("Event at %d mbuf %p refcnt %d", e, m, GET_MBUF_REFCNT(m));
 	kring->tx_pool[e] = NULL;
 	SET_MBUF_DESTRUCTOR(m, generic_mbuf_destructor);
 
@@ -777,6 +798,10 @@ generic_netmap_attach(struct ifnet *ifp)
 
 	generic_find_num_desc(ifp, &num_tx_desc, &num_rx_desc);
 	ND("Netmap ring size: TX = %d, RX = %d", num_tx_desc, num_rx_desc);
+	if (num_tx_desc == 0 || num_rx_desc == 0) {
+		D("Device has no hw slots (tx %u, rx %u)", num_tx_desc, num_rx_desc);
+		return EINVAL;
+	}
 
 	gna = malloc(sizeof(*gna), M_DEVBUF, M_NOWAIT | M_ZERO);
 	if (gna == NULL) {