 @@ -1,1140 +1,1405 @@
-/*      $NetBSD: xennetback_xenbus.c,v 1.24 2008/10/24 18:02:58 jym Exp $      */
+/*      $NetBSD: xennetback_xenbus.c,v 1.24.4.1 2009/09/28 01:46:48 snj Exp $      */
 /*
  * Copyright (c) 2006 Manuel Bouyer.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
  *      This product includes software developed by Manuel Bouyer.
  * 4. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
  */
 #include "opt_xen.h"
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/malloc.h>
 #include <sys/queue.h>
 #include <sys/kernel.h>
 #include <sys/mbuf.h>
 #include <sys/protosw.h>
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <sys/errno.h>
 #include <sys/device.h>
 #include <sys/intr.h>
 #include <net/if.h>
 #include <net/if_types.h>
 #include <net/if_dl.h>
 #include <net/route.h>
 #include <net/netisr.h>
 #include "bpfilter.h"
 #if NBPFILTER > 0
 #include <net/bpf.h>
 #include <net/bpfdesc.h>
 #endif
 #include <net/if_ether.h>
 #include <xen/xen.h>
 #include <xen/xen_shm.h>
 #include <xen/evtchn.h>
 #include <xen/xenbus.h>
 #include <xen/xennet_checksum.h>
 #include <uvm/uvm.h>
 #ifdef XENDEBUG_NET
 #define XENPRINTF(x) printf x
 #else
 #define XENPRINTF(x)
 #endif
 #define NET_TX_RING_SIZE __RING_SIZE((netif_tx_sring_t *)0, PAGE_SIZE)
 #define NET_RX_RING_SIZE __RING_SIZE((netif_rx_sring_t *)0, PAGE_SIZE)
 /* linux wants at last 16 bytes free in front of the packet */
 #define LINUX_REQUESTED_OFFSET 16
 /* hash list for TX requests */
 /* descriptor of a packet being handled by the kernel */
 struct xni_pkt {
 	int pkt_id; /* packet's ID */
 	grant_handle_t pkt_handle;
 	struct xnetback_instance *pkt_xneti; /* pointer back to our softc */
 };
 static inline void xni_pkt_unmap(struct xni_pkt *, vaddr_t);
 /* pools for xni_pkt */
 struct pool xni_pkt_pool;
 /* ratecheck(9) for pool allocation failures */
 struct timeval xni_pool_errintvl = { 30, 0 };  /* 30s, each */
 /*
  * Backend network device driver for Xen
  */
 /* state of a xnetback instance */
 typedef enum {CONNECTED, DISCONNECTING, DISCONNECTED} xnetback_state_t;
 /* we keep the xnetback instances in a linked list */
 struct xnetback_instance {
 	SLIST_ENTRY(xnetback_instance) next;
 	struct xenbus_device *xni_xbusd; /* our xenstore entry */
 	domid_t xni_domid;		/* attached to this domain */
 	uint32_t xni_handle;	/* domain-specific handle */
 	xnetback_state_t xni_status;
 	void *xni_softintr;
 	/* network interface stuff */
 	struct ethercom xni_ec;
 	struct callout xni_restart;
 	uint8_t xni_enaddr[ETHER_ADDR_LEN];
 	/* remote domain communication stuff */
 	unsigned int xni_evtchn; /* our even channel */
 	netif_tx_back_ring_t xni_txring;
 	netif_rx_back_ring_t xni_rxring;
 	grant_handle_t xni_tx_ring_handle; /* to unmap the ring */
 	grant_handle_t xni_rx_ring_handle;
 	vaddr_t xni_tx_ring_va; /* to unmap the ring */
 	vaddr_t xni_rx_ring_va;
 };
 #define xni_if    xni_ec.ec_if
 #define xni_bpf   xni_if.if_bpf
        void xvifattach(int);
 static int  xennetback_ifioctl(struct ifnet *, u_long, void *);
 static void xennetback_ifstart(struct ifnet *);
-static void xennetback_ifsoftstart(void *);
+static void xennetback_ifsoftstart_transfer(void *);
 static void xennetback_ifsoftstart_copy(void *);
 static void xennetback_ifwatchdog(struct ifnet *);
 static int  xennetback_ifinit(struct ifnet *);
 static void xennetback_ifstop(struct ifnet *, int);
 static int  xennetback_xenbus_create(struct xenbus_device *);
 static int  xennetback_xenbus_destroy(void *);
 static void xennetback_frontend_changed(void *, XenbusState);
 static inline void xennetback_tx_response(struct xnetback_instance *,
     int, int);
 static void xennetback_tx_free(struct mbuf * , void *, size_t, void *);
 SLIST_HEAD(, xnetback_instance) xnetback_instances;
 static struct xnetback_instance *xnetif_lookup(domid_t, uint32_t);
 static int  xennetback_evthandler(void *);
 static struct xenbus_backend_driver xvif_backend_driver = {
 	.xbakd_create = xennetback_xenbus_create,
 	.xbakd_type = "vif"
 };
 /*
  * Number of packets to transmit in one hypercall (= number of pages to
  * transmit at once).
  */
 #define NB_XMIT_PAGES_BATCH 64
 /*
  * We will transfers a mapped page to the remote domain, and remap another
  * page in place immediatly. For this we keep a list of pages available.
  * When the list is empty, we ask the hypervisor to give us
  * NB_XMIT_PAGES_BATCH pages back.
  */
 static unsigned long mcl_pages[NB_XMIT_PAGES_BATCH]; /* our physical pages */
 int mcl_pages_alloc; /* current index in mcl_pages */
 static int  xennetback_get_mcl_page(paddr_t *);
 static void xennetback_get_new_mcl_pages(void);
 /*
  * If we can't transfer the mbuf directly, we have to copy it to a page which
  * will be transfered to the remote domain. We use a pool_cache
  * for this, or the mbuf cluster pool cache if MCLBYTES == PAGE_SIZE
  */
 #if MCLBYTES != PAGE_SIZE
 pool_cache_t xmit_pages_cache;
 #endif
 pool_cache_t xmit_pages_cachep;
 /* arrays used in xennetback_ifstart(), too large to allocate on stack */
 static mmu_update_t xstart_mmu[NB_XMIT_PAGES_BATCH];
 static multicall_entry_t xstart_mcl[NB_XMIT_PAGES_BATCH + 1];
-static gnttab_transfer_t xstart_gop[NB_XMIT_PAGES_BATCH];
+static gnttab_transfer_t xstart_gop_transfer[NB_XMIT_PAGES_BATCH];
 static gnttab_copy_t     xstart_gop_copy[NB_XMIT_PAGES_BATCH];
 struct mbuf *mbufs_sent[NB_XMIT_PAGES_BATCH];
 struct _pages_pool_free {
 	vaddr_t va;
 	paddr_t pa;
 } pages_pool_free[NB_XMIT_PAGES_BATCH];
 static inline void
 xni_pkt_unmap(struct xni_pkt *pkt, vaddr_t pkt_va)
+{
 	xen_shm_unmap(pkt_va, 1, &pkt->pkt_handle);
 	pool_put(&xni_pkt_pool, pkt);
+}
 void
 xvifattach(int n)
+{
 	int i;
 	struct pglist mlist;
 	struct vm_page *pg;
 	XENPRINTF(("xennetback_init\n"));
 	/*
 	 * steal some non-managed pages to the VM system, to remplace
 	 * mbuf cluster or xmit_pages_pool pages given to foreing domains.
 	 */
 	if (uvm_pglistalloc(PAGE_SIZE * NB_XMIT_PAGES_BATCH, 0, 0xffffffff,
 , 0, &mlist, NB_XMIT_PAGES_BATCH, 0) != 0)
 		panic("xennetback_init: uvm_pglistalloc");
 	for (i = 0, pg = mlist.tqh_first; pg != NULL;
 	    pg = pg->pageq.queue.tqe_next, i++)
 		mcl_pages[i] = xpmap_ptom(VM_PAGE_TO_PHYS(pg)) >> PAGE_SHIFT;
 	if (i != NB_XMIT_PAGES_BATCH)
 		panic("xennetback_init: %d mcl pages", i);
 	mcl_pages_alloc = NB_XMIT_PAGES_BATCH - 1;
 	/* initialise pools */
 	pool_init(&xni_pkt_pool, sizeof(struct xni_pkt), 0, 0, 0,
 	    "xnbpkt", NULL, IPL_VM);
 #if MCLBYTES != PAGE_SIZE
 	xmit_pages_cache = pool_cache_init(PAGE_SIZE, 0, 0, 0, "xnbxm", NULL,
 	    IPL_VM, NULL, NULL, NULL);
 	xmit_pages_cachep = xmit_pages_cache;
 #else
 	xmit_pages_cachep = mcl_cache;
 #endif
 	SLIST_INIT(&xnetback_instances);
 	xenbus_backend_register(&xvif_backend_driver);
+}
 static int
 xennetback_xenbus_create(struct xenbus_device *xbusd)
+{
 	struct xnetback_instance *xneti;
 	long domid, handle;
 	struct ifnet *ifp;
 	extern int ifqmaxlen; /* XXX */
 	char *val, *e, *p;
 	int i, err;
 	struct xenbus_transaction *xbt;
 	if ((err = xenbus_read_ul(NULL, xbusd->xbusd_path,
 	    "frontend-id", &domid, 10)) != 0) {
 		aprint_error("xvif: can' read %s/frontend-id: %d\n",
 		    xbusd->xbusd_path, err);
 		return err;
+	}
 	if ((err = xenbus_read_ul(NULL, xbusd->xbusd_path,
 	    "handle", &handle, 10)) != 0) {
 		aprint_error("xvif: can' read %s/handle: %d\n",
 		    xbusd->xbusd_path, err);
 		return err;
+	}
 	if (xnetif_lookup(domid, handle) != NULL) {
 		return EEXIST;
+	}
 	xneti = malloc(sizeof(struct xnetback_instance), M_DEVBUF,
 	    M_NOWAIT | M_ZERO);
 	if (xneti == NULL) {
 		return ENOMEM;
+	}
 	xneti->xni_domid = domid;
 	xneti->xni_handle = handle;
 	xneti->xni_status = DISCONNECTED;
 	xbusd->xbusd_u.b.b_cookie = xneti;
 	xbusd->xbusd_u.b.b_detach = xennetback_xenbus_destroy;
 	xneti->xni_xbusd = xbusd;
 	xneti->xni_softintr = softint_establish(SOFTINT_NET,
 	    xennetback_ifsoftstart, xneti);
 	if (xneti->xni_softintr == NULL) {
 		err = ENOMEM;
 		goto fail;
 	ifp = &xneti->xni_if;
 	ifp->if_softc = xneti;
 	/* read mac address */
 	if ((err = xenbus_read(NULL, xbusd->xbusd_path, "mac", NULL, &val))) {
 		aprint_error("xvif: can' read %s/mac: %d\n",
 		    xbusd->xbusd_path, err);
 		goto fail;
+	}
 	for (i = 0, p = val; i < 6; i++) {
 		xneti->xni_enaddr[i] = strtoul(p, &e, 16);
 		if ((e[0] == '\0' && i != 5) && e[0] != ':') {
 			aprint_error("xvif: %s is not a valid mac address\n",
 			    val);
 			err = EINVAL;
 			goto fail;
+		}
 		p = &e[1];
+	}
 	free(val, M_DEVBUF);
 	/* we can't use the same MAC addr as our guest */
 	xneti->xni_enaddr[3]++;
 	/* create pseudo-interface */
 	snprintf(xneti->xni_if.if_xname, IFNAMSIZ, "xvif%d.%d",
 	    (int)domid, (int)handle);
 	aprint_verbose_ifnet(ifp, "Ethernet address %s\n",
 	    ether_sprintf(xneti->xni_enaddr));
 	ifp->if_flags =
 	    IFF_BROADCAST|IFF_SIMPLEX|IFF_NOTRAILERS|IFF_MULTICAST;
 	ifp->if_snd.ifq_maxlen =
 	    max(ifqmaxlen, NET_TX_RING_SIZE * 2);
 	ifp->if_capabilities = IFCAP_CSUM_TCPv4_Tx | IFCAP_CSUM_UDPv4_Tx;
 	ifp->if_ioctl = xennetback_ifioctl;
 	ifp->if_start = xennetback_ifstart;
 	ifp->if_watchdog = xennetback_ifwatchdog;
 	ifp->if_init = xennetback_ifinit;
 	ifp->if_stop = xennetback_ifstop;
 	ifp->if_timer = 0;
 	IFQ_SET_READY(&ifp->if_snd);
 	if_attach(ifp);
 	ether_ifattach(&xneti->xni_if, xneti->xni_enaddr);
 	SLIST_INSERT_HEAD(&xnetback_instances, xneti, next);
 	xbusd->xbusd_otherend_changed = xennetback_frontend_changed;
 	do {
 		xbt = xenbus_transaction_start();
 		if (xbt == NULL) {
 			printf("xbdback %s: can't start transaction\n",
 			    xbusd->xbusd_path);
 			goto fail;
+		}
 		err = xenbus_printf(xbt, xbusd->xbusd_path,
 		    "feature-rx-copy", "%d", 1);
 		if (err) {
 			printf("xbdback: failed to write %s/feature-rx-copy: "
 			    "%d\n", xbusd->xbusd_path, err);
 			goto abort_xbt;
+		}
 		err = xenbus_printf(xbt, xbusd->xbusd_path,
 		    "feature-rx-flip", "%d", 1);
 		if (err) {
 			printf("xbdback: failed to write %s/feature-rx-flip: "
 			    "%d\n", xbusd->xbusd_path, err);
 			goto abort_xbt;
+		}
 	} while ((err = xenbus_transaction_end(xbt, 0)) == EAGAIN);
 	if (err) {
 		printf("xbdback %s: can't end transaction: %d\n",
 		    xbusd->xbusd_path, err);
+	}
 	err = xenbus_switch_state(xbusd, NULL, XenbusStateInitWait);
 	if (err) {
 		printf("failed to switch state on %s: %d\n",
 		    xbusd->xbusd_path, err);
 		goto fail;
+	}
 	if (err) {
 		printf("failed to write %s/hotplug-status: %d\n",
 		    xbusd->xbusd_path, err);
 		goto fail;
+	}
 	return 0;
 abort_xbt:
 	xenbus_transaction_end(xbt, 1);
 fail:
 	free(xneti, M_DEVBUF);
 	return err;
+}
 int
 xennetback_xenbus_destroy(void *arg)
+{
 	struct xnetback_instance *xneti = arg;
 	struct gnttab_unmap_grant_ref op;
 	int err;
 #if 0
 	if (xneti->xni_status == CONNECTED) {
 		return EBUSY;
+	}
 #endif
 	aprint_verbose_ifnet(&xneti->xni_if, "disconnecting\n");
 	hypervisor_mask_event(xneti->xni_evtchn);
 	event_remove_handler(xneti->xni_evtchn, xennetback_evthandler, xneti);
 	softint_disestablish(xneti->xni_softintr);
 	SLIST_REMOVE(&xnetback_instances,
 	    xneti, xnetback_instance, next);
 	ether_ifdetach(&xneti->xni_if);
 	if_detach(&xneti->xni_if);
 	if (xneti->xni_txring.sring) {
 		op.host_addr = xneti->xni_tx_ring_va;
 		op.handle = xneti->xni_tx_ring_handle;
 		op.dev_bus_addr = 0;
 		err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
 		    &op, 1);
 		if (err)
 			aprint_error_ifnet(&xneti->xni_if,
 					"unmap_grant_ref failed: %d\n", err);
+	}
 	if (xneti->xni_rxring.sring) {
 		op.host_addr = xneti->xni_rx_ring_va;
 		op.handle = xneti->xni_rx_ring_handle;
 		op.dev_bus_addr = 0;
 		err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
 		    &op, 1);
 		if (err)
 			aprint_error_ifnet(&xneti->xni_if,
 					"unmap_grant_ref failed: %d\n", err);
+	}
 	uvm_km_free(kernel_map, xneti->xni_tx_ring_va,
 	    PAGE_SIZE, UVM_KMF_VAONLY);
 	uvm_km_free(kernel_map, xneti->xni_rx_ring_va,
 	    PAGE_SIZE, UVM_KMF_VAONLY);
 	free(xneti, M_DEVBUF);
 	return 0;
+}
 static void
 xennetback_frontend_changed(void *arg, XenbusState new_state)
+{
 	struct xnetback_instance *xneti = arg;
 	struct xenbus_device *xbusd = xneti->xni_xbusd;
 	int err;
 	netif_tx_sring_t *tx_ring;
 	netif_rx_sring_t *rx_ring;
 	struct gnttab_map_grant_ref op;
 	evtchn_op_t evop;
 	u_long tx_ring_ref, rx_ring_ref;
-	u_long revtchn;
+	u_long revtchn, rx_copy;
 	XENPRINTF(("%s: new state %d\n", xneti->xni_if.if_xname, new_state));
 	switch(new_state) {
 	case XenbusStateInitialising:
 	case XenbusStateInitialised:
 		break;
 	case XenbusStateConnected:
 		/* read comunication informations */
 		err = xenbus_read_ul(NULL, xbusd->xbusd_otherend,
 		    "tx-ring-ref", &tx_ring_ref, 10);
 		if (err) {
 			xenbus_dev_fatal(xbusd, err, "reading %s/tx-ring-ref",
 			    xbusd->xbusd_otherend);
 			break;
+		}
 		err = xenbus_read_ul(NULL, xbusd->xbusd_otherend,
 		    "rx-ring-ref", &rx_ring_ref, 10);
 		if (err) {
 			xenbus_dev_fatal(xbusd, err, "reading %s/rx-ring-ref",
 			    xbusd->xbusd_otherend);
 			break;
+		}
 		err = xenbus_read_ul(NULL, xbusd->xbusd_otherend,
 		    "event-channel", &revtchn, 10);
 		if (err) {
 			xenbus_dev_fatal(xbusd, err, "reading %s/event-channel",
 			    xbusd->xbusd_otherend);
 			break;
+		}
 		err = xenbus_read_ul(NULL, xbusd->xbusd_otherend,
 		    "request-rx-copy", &rx_copy, 10);
 		if (err == ENOENT)
 			rx_copy = 0;
 		else if (err) {
 			xenbus_dev_fatal(xbusd, err, "reading %s/request-rx-copy",
 			    xbusd->xbusd_otherend);
 			break;
+		}
 		if (rx_copy)
 			xneti->xni_softintr = softint_establish(SOFTINT_NET,
 			    xennetback_ifsoftstart_copy, xneti);
 		else
 			xneti->xni_softintr = softint_establish(SOFTINT_NET,
 			    xennetback_ifsoftstart_transfer, xneti);
 		if (xneti->xni_softintr == NULL) {
 			err = ENOMEM;
 			xenbus_dev_fatal(xbusd, ENOMEM,
 			    "can't allocate softint", xbusd->xbusd_otherend);
 			break;
+		}
 		/* allocate VA space and map rings */
 		xneti->xni_tx_ring_va = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
 		    UVM_KMF_VAONLY);
 		if (xneti->xni_tx_ring_va == 0) {
 			xenbus_dev_fatal(xbusd, ENOMEM,
 			    "can't get VA for tx ring", xbusd->xbusd_otherend);
 			break;
+		}
 		tx_ring = (void *)xneti->xni_tx_ring_va;
 		xneti->xni_rx_ring_va = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
 		    UVM_KMF_VAONLY);
 		if (xneti->xni_rx_ring_va == 0) {
 			xenbus_dev_fatal(xbusd, ENOMEM,
 			    "can't get VA for rx ring", xbusd->xbusd_otherend);
 			goto err1;
+		}
 		rx_ring = (void *)xneti->xni_rx_ring_va;
 		op.host_addr = xneti->xni_tx_ring_va;
 		op.flags = GNTMAP_host_map;
 		op.ref = tx_ring_ref;
 		op.dom = xneti->xni_domid;
 		err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 		if (err || op.status) {
 			printf("%s: can't map TX grant ref: %d/%d\n",
 			    xneti->xni_if.if_xname, err, op.status);
 			goto err2;
+		}
 		xneti->xni_tx_ring_handle = op.handle;
 		op.host_addr = xneti->xni_rx_ring_va;
 		op.flags = GNTMAP_host_map;
 		op.ref = rx_ring_ref;
 		op.dom = xneti->xni_domid;
 		err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
 		if (err || op.status) {
 			printf("%s: can't map RX grant ref: %d/%d\n",
 			    xneti->xni_if.if_xname, err, op.status);
 			goto err2;
+		}
 		xneti->xni_rx_ring_handle = op.handle;
 		BACK_RING_INIT(&xneti->xni_txring, tx_ring, PAGE_SIZE);
 		BACK_RING_INIT(&xneti->xni_rxring, rx_ring, PAGE_SIZE);
 		evop.cmd = EVTCHNOP_bind_interdomain;
 		evop.u.bind_interdomain.remote_dom = xneti->xni_domid;
 		evop.u.bind_interdomain.remote_port = revtchn;
 		err = HYPERVISOR_event_channel_op(&evop);
 		if (err) {
 			printf("%s: can't get event channel: %d\n",
 			    xneti->xni_if.if_xname, err);
 			goto err2;
+		}
 		xneti->xni_evtchn = evop.u.bind_interdomain.local_port;
 		x86_sfence();
 		xneti->xni_status = CONNECTED;
 		xenbus_switch_state(xbusd, NULL, XenbusStateConnected);
 		x86_sfence();
 		event_set_handler(xneti->xni_evtchn, xennetback_evthandler,
 		    xneti, IPL_NET, xneti->xni_if.if_xname);
 		xennetback_ifinit(&xneti->xni_if);
 		hypervisor_enable_event(xneti->xni_evtchn);
 		hypervisor_notify_via_evtchn(xneti->xni_evtchn);
 		break;
 	case XenbusStateClosing:
 		xneti->xni_status = DISCONNECTING;
 		xneti->xni_if.if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
 		xneti->xni_if.if_timer = 0;
 		xenbus_switch_state(xbusd, NULL, XenbusStateClosing);
 		break;
 	case XenbusStateClosed:
 		/* otherend_changed() should handle it for us */
 		panic("xennetback_frontend_changed: closed\n");
 	case XenbusStateUnknown:
 	case XenbusStateInitWait:
 	default:
 		aprint_error("%s: invalid frontend state %d\n",
 		    xneti->xni_if.if_xname, new_state);
 		break;
+	}
 	return;
 err2:
 	uvm_km_free(kernel_map, xneti->xni_rx_ring_va,
 	    PAGE_SIZE, UVM_KMF_VAONLY);
 err1:
 	uvm_km_free(kernel_map, xneti->xni_tx_ring_va,
 	    PAGE_SIZE, UVM_KMF_VAONLY);
+}
 /* lookup a xneti based on domain id and interface handle */
 static struct xnetback_instance *
 xnetif_lookup(domid_t dom , uint32_t handle)
+{
 	struct xnetback_instance *xneti;
 	SLIST_FOREACH(xneti, &xnetback_instances, next) {
 		if (xneti->xni_domid == dom && xneti->xni_handle == handle)
 			return xneti;
+	}
 	return NULL;
+}
 /* get a page to remplace a mbuf cluster page given to a domain */
 static int
 xennetback_get_mcl_page(paddr_t *map)
+{
 	if (mcl_pages_alloc < 0)
 		/*
 		 * we exhausted our allocation. We can't allocate new ones yet
 		 * because the current pages may not have been loaned to
 		 * the remote domain yet. We have to let the caller do this.
 		 */
 		return -1;
 	*map = mcl_pages[mcl_pages_alloc] << PAGE_SHIFT;
 	mcl_pages_alloc--;
 	return 0;
+}
 static void
 xennetback_get_new_mcl_pages(void)
+{
 	int nb_pages;
 	struct xen_memory_reservation res;
 	/* get some new pages. */
 	res.extent_start = mcl_pages;
 	res.nr_extents = NB_XMIT_PAGES_BATCH;
 	res.extent_order = 0;
 	res.address_bits = 0;
 	res.domid = DOMID_SELF;
 	nb_pages = HYPERVISOR_memory_op(XENMEM_increase_reservation, &res);
 	if (nb_pages <= 0) {
 		printf("xennetback: can't get new mcl pages (%d)\n", nb_pages);
 		return;
+	}
 	if (nb_pages != NB_XMIT_PAGES_BATCH)
 		printf("xennetback: got only %d new mcl pages\n", nb_pages);
 	mcl_pages_alloc = nb_pages - 1;
+}
 static inline void
 xennetback_tx_response(struct xnetback_instance *xneti, int id, int status)
+{
 	RING_IDX resp_prod;
 	netif_tx_response_t *txresp;
 	int do_event;
 	resp_prod = xneti->xni_txring.rsp_prod_pvt;
 	txresp = RING_GET_RESPONSE(&xneti->xni_txring, resp_prod);
 	txresp->id = id;
 	txresp->status = status;
 	xneti->xni_txring.rsp_prod_pvt++;
 	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&xneti->xni_txring, do_event);
 	if (do_event) {
 		XENPRINTF(("%s send event\n", xneti->xni_if.if_xname));
 		hypervisor_notify_via_evtchn(xneti->xni_evtchn);
+	}
+}
 static int
 xennetback_evthandler(void *arg)
+{
 	struct xnetback_instance *xneti = arg;
 	struct ifnet *ifp = &xneti->xni_if;
 	netif_tx_request_t *txreq;
 	struct xni_pkt *pkt;
 	vaddr_t pkt_va;
 	struct mbuf *m;
 	int receive_pending, err;
 	RING_IDX req_cons;
 	XENPRINTF(("xennetback_evthandler "));
 	req_cons = xneti->xni_txring.req_cons;
 	x86_lfence();
 	while (1) {
 		x86_lfence(); /* be sure to read the request before updating */
 		xneti->xni_txring.req_cons = req_cons;
 		x86_sfence();
 		RING_FINAL_CHECK_FOR_REQUESTS(&xneti->xni_txring,
 		    receive_pending);
 		if (receive_pending == 0)
 			break;
 		txreq = RING_GET_REQUEST(&xneti->xni_txring, req_cons);
 		x86_lfence();
 		XENPRINTF(("%s pkt size %d\n", xneti->xni_if.if_xname,
 		    txreq->size));
 		req_cons++;
 		if (__predict_false((ifp->if_flags & (IFF_UP | IFF_RUNNING)) !=
 		    (IFF_UP | IFF_RUNNING))) {
 			/* interface not up, drop */
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_DROPPED);
 			continue;
+		}
 		/*
 		 * Do some sanity checks, and map the packet's page.
 		 */
 		if (__predict_false(txreq->size < ETHER_HDR_LEN ||
 		   txreq->size > (ETHER_MAX_LEN - ETHER_CRC_LEN))) {
 			printf("%s: packet size %d too big\n",
 			    ifp->if_xname, txreq->size);
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_ERROR);
 			ifp->if_ierrors++;
 			continue;
+		}
 		/* don't cross page boundaries */
 		if (__predict_false(
 		    txreq->offset + txreq->size > PAGE_SIZE)) {
 			printf("%s: packet cross page boundary\n",
 			    ifp->if_xname);
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_ERROR);
 			ifp->if_ierrors++;
 			continue;
+		}
 		/* get a mbuf for this packet */
 		MGETHDR(m, M_DONTWAIT, MT_DATA);
 		if (__predict_false(m == NULL)) {
 			static struct timeval lasttime;
 			if (ratecheck(&lasttime, &xni_pool_errintvl))
 				printf("%s: mbuf alloc failed\n",
 				    ifp->if_xname);
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_DROPPED);
 			ifp->if_ierrors++;
 			continue;
+		}
 		XENPRINTF(("%s pkt offset %d size %d id %d req_cons %d\n",
 		    xneti->xni_if.if_xname, txreq->offset,
 		    txreq->size, txreq->id, MASK_NETIF_TX_IDX(req_cons)));
 		pkt = pool_get(&xni_pkt_pool, PR_NOWAIT);
 		if (__predict_false(pkt == NULL)) {
 			static struct timeval lasttime;
 			if (ratecheck(&lasttime, &xni_pool_errintvl))
 				printf("%s: xnbpkt alloc failed\n",
 				    ifp->if_xname);
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_DROPPED);
 			ifp->if_ierrors++;
 			m_freem(m);
 			continue;
+		}
 		err = xen_shm_map(1, xneti->xni_domid, &txreq->gref, &pkt_va,
 		    &pkt->pkt_handle, XSHM_RO);
 		if (__predict_false(err == ENOMEM)) {
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_DROPPED);
 			ifp->if_ierrors++;
 			pool_put(&xni_pkt_pool, pkt);
 			m_freem(m);
 			continue;
+		}
 		if (__predict_false(err)) {
 			printf("%s: mapping foreing page failed: %d\n",
 			    xneti->xni_if.if_xname, err);
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_ERROR);
 			ifp->if_ierrors++;
 			pool_put(&xni_pkt_pool, pkt);
 			m_freem(m);
 			continue;
+		}
 		if ((ifp->if_flags & IFF_PROMISC) == 0) {
 			struct ether_header *eh =
 			    (void*)(pkt_va + txreq->offset);
 			if (ETHER_IS_MULTICAST(eh->ether_dhost) == 0 &&
 			    memcmp(CLLADDR(ifp->if_sadl), eh->ether_dhost,
 			    ETHER_ADDR_LEN) != 0) {
 				xni_pkt_unmap(pkt, pkt_va);
 				m_freem(m);
 				xennetback_tx_response(xneti, txreq->id,
 				    NETIF_RSP_OKAY);
 				continue; /* packet is not for us */
+			}
+		}
 #ifdef notyet
 a lot of work is needed in the tcp stack to handle read-only ext storage
 so always copy for now.
 		if (((req_cons + 1) & (NET_TX_RING_SIZE - 1)) ==
 		    (xneti->xni_txring.rsp_prod_pvt & (NET_TX_RING_SIZE - 1)))
 #else
 		if (1)
 #endif /* notyet */
+		{
 			/*
 			 * This is the last TX buffer. Copy the data and
 			 * ack it. Delaying it until the mbuf is
 			 * freed will stall transmit.
 			 */
 			m->m_len = min(MHLEN, txreq->size);
 			m->m_pkthdr.len = 0;
 			m_copyback(m, 0, txreq->size,
 			    (void *)(pkt_va + txreq->offset));
 			xni_pkt_unmap(pkt, pkt_va);
 			if (m->m_pkthdr.len < txreq->size) {
 				ifp->if_ierrors++;
 				m_freem(m);
 				xennetback_tx_response(xneti, txreq->id,
 				    NETIF_RSP_DROPPED);
 				continue;
+			}
 			xennetback_tx_response(xneti, txreq->id,
 			    NETIF_RSP_OKAY);
 		} else {
 			pkt->pkt_id = txreq->id;
 			pkt->pkt_xneti = xneti;
 			MEXTADD(m, pkt_va + txreq->offset,
 			    txreq->size, M_DEVBUF, xennetback_tx_free, pkt);
 			m->m_pkthdr.len = m->m_len = txreq->size;
 			m->m_flags |= M_EXT_ROMAP;
+		}
 		if ((txreq->flags & NETTXF_csum_blank) != 0) {
 			xennet_checksum_fill(&m);
 			if (m == NULL) {
 				ifp->if_ierrors++;
 				continue;
+			}
+		}
 		m->m_pkthdr.rcvif = ifp;
 		ifp->if_ipackets++;
 #if NBPFILTER > 0
 		if (ifp->if_bpf)
 			bpf_mtap(ifp->if_bpf, m);
 #endif
 		(*ifp->if_input)(ifp, m);
+	}
 	x86_lfence(); /* be sure to read the request before updating pointer */
 	xneti->xni_txring.req_cons = req_cons;
 	x86_sfence();
 	/* check to see if we can transmit more packets */
 	softint_schedule(xneti->xni_softintr);
 	return 1;
+}
 static void
 xennetback_tx_free(struct mbuf *m, void *va, size_t size, void *arg)
+{
 	int s = splnet();
 	struct xni_pkt *pkt = arg;
 	struct xnetback_instance *xneti = pkt->pkt_xneti;
 	XENPRINTF(("xennetback_tx_free\n"));
 	xennetback_tx_response(xneti, pkt->pkt_id, NETIF_RSP_OKAY);
 	xni_pkt_unmap(pkt, (vaddr_t)va & ~PAGE_MASK);
 	if (m)
 		pool_cache_put(mb_cache, m);
 	splx(s);
+}
 static int
 xennetback_ifioctl(struct ifnet *ifp, u_long cmd, void *data)
+{
 	//struct xnetback_instance *xneti = ifp->if_softc;
 	//struct ifreq *ifr = (struct ifreq *)data;
 	int s, error;
 	s = splnet();
 	error = ether_ioctl(ifp, cmd, data);
 	if (error == ENETRESET)
 		error = 0;
 	splx(s);
 	return error;
+}
 static void
 xennetback_ifstart(struct ifnet *ifp)
+{
 	struct xnetback_instance *xneti = ifp->if_softc;
 	/*
 	 * The Xen communication channel is much more efficient if we can
 	 * schedule batch of packets for the domain. To achieve this, we
 	 * schedule a soft interrupt, and just return. This way, the network
 	 * stack will enqueue all pending mbufs in the interface's send queue
-	 * before it is processed by xennet_softstart().
+	 * before it is processed by the soft inetrrupt handler().
 	 */
 	softint_schedule(xneti->xni_softintr);
+}
 static void
-xennetback_ifsoftstart(void *arg)
+xennetback_ifsoftstart_transfer(void *arg)
+{
 	struct xnetback_instance *xneti = arg;
 	struct ifnet *ifp = &xneti->xni_if;
 	struct mbuf *m;
 	vaddr_t xmit_va;
 	paddr_t xmit_pa;
 	paddr_t xmit_ma;
 	paddr_t newp_ma = 0; /* XXX gcc */
 	int i, j, nppitems;
 	mmu_update_t *mmup;
 	multicall_entry_t *mclp;
 	netif_rx_response_t *rxresp;
 	RING_IDX req_prod, resp_prod;
 	int do_event = 0;
 	gnttab_transfer_t *gop;
 	int id, offset;
-	XENPRINTF(("xennetback_ifsoftstart "));
+	XENPRINTF(("xennetback_ifsoftstart_transfer "));
 	int s = splnet();
 	if (__predict_false(
 	    (ifp->if_flags & (IFF_RUNNING|IFF_OACTIVE)) != IFF_RUNNING)) {
 		splx(s);
 		return;
+	}
 	while (!IFQ_IS_EMPTY(&ifp->if_snd)) {
 		XENPRINTF(("pkt\n"));
 		req_prod = xneti->xni_rxring.sring->req_prod;
 		resp_prod = xneti->xni_rxring.rsp_prod_pvt;
 		x86_lfence();
 		mmup = xstart_mmu;
 		mclp = xstart_mcl;
-		gop = xstart_gop;
+		gop = xstart_gop_transfer;
 		for (nppitems = 0, i = 0; !IFQ_IS_EMPTY(&ifp->if_snd);) {
 			XENPRINTF(("have a packet\n"));
 			IFQ_POLL(&ifp->if_snd, m);
 			if (__predict_false(m == NULL))
 				panic("xennetback_ifstart: IFQ_POLL");
 			if (__predict_false(
 			    req_prod == xneti->xni_rxring.req_cons ||
 			    xneti->xni_rxring.req_cons - resp_prod ==
 			    NET_RX_RING_SIZE)) {
 				/* out of ring space */
 				XENPRINTF(("xennetback_ifstart: ring full "
 				    "req_prod 0x%x req_cons 0x%x resp_prod "
 				    "0x%x\n",
 				    req_prod, xneti->xni_rxring.req_cons,
 				    resp_prod));
 				ifp->if_timer = 1;
 				break;
+			}
 			if (__predict_false(i == NB_XMIT_PAGES_BATCH))
 				break; /* we filled the array */
 			if (__predict_false(
 			    xennetback_get_mcl_page(&newp_ma) != 0))
 				break; /* out of memory */
 			if ((m->m_flags & M_CLUSTER) != 0 &&
 			    !M_READONLY(m) && MCLBYTES == PAGE_SIZE) {
 				/* we can give this page away */
 				xmit_pa = m->m_ext.ext_paddr;
 				xmit_ma = xpmap_ptom(xmit_pa);
 				xmit_va = (vaddr_t)m->m_ext.ext_buf;
 				KASSERT(xmit_pa != M_PADDR_INVALID);
 				KASSERT((xmit_va & PAGE_MASK) == 0);
 				offset = m->m_data - m->m_ext.ext_buf;
 			} else {
 				/* we have to copy the packet */
 				xmit_va = (vaddr_t)pool_cache_get_paddr(
 				    xmit_pages_cachep,
 				    PR_NOWAIT, &xmit_pa);
 				if (__predict_false(xmit_va == 0))
 					break; /* out of memory */
 				KASSERT(xmit_pa != POOL_PADDR_INVALID);
 				xmit_ma = xpmap_ptom(xmit_pa);
 				XENPRINTF(("xennetback_get_xmit_page: got va "
 				    "0x%x ma 0x%x\n", (u_int)xmit_va,
 				    (u_int)xmit_ma));
 				m_copydata(m, 0, m->m_pkthdr.len,
 				    (char *)xmit_va + LINUX_REQUESTED_OFFSET);
 				offset = LINUX_REQUESTED_OFFSET;
 				pages_pool_free[nppitems].va = xmit_va;
 				pages_pool_free[nppitems].pa = xmit_pa;
 				nppitems++;
+			}
 			/* start filling ring */
 			gop->ref = RING_GET_REQUEST(&xneti->xni_rxring,
 			    xneti->xni_rxring.req_cons)->gref;
 			id = RING_GET_REQUEST(&xneti->xni_rxring,
 			    xneti->xni_rxring.req_cons)->id;
 			x86_lfence();
 			xneti->xni_rxring.req_cons++;
 			rxresp = RING_GET_RESPONSE(&xneti->xni_rxring,
 			    resp_prod);
 			rxresp->id = id;
 			rxresp->offset = offset;
 			rxresp->status = m->m_pkthdr.len;
 			if ((m->m_pkthdr.csum_flags &
 			    (M_CSUM_TCPv4 | M_CSUM_UDPv4)) != 0) {
 				rxresp->flags = NETRXF_csum_blank;
 			} else {
 				rxresp->flags = 0;
+			}
 			/*
 			 * transfers the page containing the packet to the
 			 * remote domain, and map newp in place.
 			 */
 			xpmap_phys_to_machine_mapping[
 			    (xmit_pa - XPMAP_OFFSET) >> PAGE_SHIFT] =
 			    newp_ma >> PAGE_SHIFT;
 			MULTI_update_va_mapping(mclp, xmit_va,
 			    newp_ma | PG_V | PG_RW | PG_U | PG_M, 0);
 			mclp++;
 			gop->mfn = xmit_ma >> PAGE_SHIFT;
 			gop->domid = xneti->xni_domid;
 			gop++;
 			mmup->ptr = newp_ma | MMU_MACHPHYS_UPDATE;
 			mmup->val = (xmit_pa - XPMAP_OFFSET) >> PAGE_SHIFT;
 			mmup++;
 			/* done with this packet */
 			IFQ_DEQUEUE(&ifp->if_snd, m);
 			mbufs_sent[i] = m;
 			resp_prod++;
 			i++; /* this packet has been queued */
 			ifp->if_opackets++;
 #if NBPFILTER > 0
 			if (ifp->if_bpf)
 				bpf_mtap(ifp->if_bpf, m);
 #endif
+		}
 		if (i != 0) {
 			/*
 			 * We may have allocated buffers which have entries
 			 * outstanding in the page update queue -- make sure
 			 * we flush those first!
 			 */
 			int svm = splvm();
 			xpq_flush_queue();
 			splx(svm);
 			mclp[-1].args[MULTI_UVMFLAGS_INDEX] =
 			    UVMF_TLB_FLUSH|UVMF_ALL;
 			mclp->op = __HYPERVISOR_mmu_update;
 			mclp->args[0] = (unsigned long)xstart_mmu;
 			mclp->args[1] = i;
 			mclp->args[2] = 0;
 			mclp->args[3] = DOMID_SELF;
 			mclp++;
 			/* update the MMU */
 			if (HYPERVISOR_multicall(xstart_mcl, i + 1) != 0) {
 				panic("%s: HYPERVISOR_multicall failed",
 				    ifp->if_xname);
+			}
 			for (j = 0; j < i + 1; j++) {
 				if (xstart_mcl[j].result != 0) {
 					printf("%s: xstart_mcl[%d] "
 					    "failed (%lu)\n", ifp->if_xname,
 					    j, xstart_mcl[j].result);
 					printf("%s: req_prod %u req_cons "
 					    "%u rsp_prod %u rsp_prod_pvt %u "
 					    "i %u\n",
 					    ifp->if_xname,
 					    xneti->xni_rxring.sring->req_prod,
 					    xneti->xni_rxring.req_cons,
 					    xneti->xni_rxring.sring->rsp_prod,
 					    xneti->xni_rxring.rsp_prod_pvt,
 					    i);
+				}
+			}
 			if (HYPERVISOR_grant_table_op(GNTTABOP_transfer,
-			    xstart_gop, i) != 0) {
+			    xstart_gop_transfer, i) != 0) {
 				panic("%s: GNTTABOP_transfer failed",
 				    ifp->if_xname);
+			}
 			for (j = 0; j < i; j++) {
-				if (xstart_gop[j].status != 0) {
+				if (xstart_gop_transfer[j].status != GNTST_okay) {
 					printf("%s GNTTABOP_transfer[%d] %d\n",
 					    ifp->if_xname,
-					    j, xstart_gop[j].status);
+					    j, xstart_gop_transfer[j].status);
 					printf("%s: req_prod %u req_cons "
 					    "%u rsp_prod %u rsp_prod_pvt %u "
 					    "i %d\n",
 					    ifp->if_xname,
 					    xneti->xni_rxring.sring->req_prod,
 					    xneti->xni_rxring.req_cons,
 					    xneti->xni_rxring.sring->rsp_prod,
 					    xneti->xni_rxring.rsp_prod_pvt,
 					    i);
 					rxresp = RING_GET_RESPONSE(
 					    &xneti->xni_rxring,
 					    xneti->xni_rxring.rsp_prod_pvt + j);
 					rxresp->status = NETIF_RSP_ERROR;
+				}
+			}
 			/* update pointer */
 			KASSERT(
 			    xneti->xni_rxring.rsp_prod_pvt + i == resp_prod);
 			xneti->xni_rxring.rsp_prod_pvt = resp_prod;
 			RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
 			    &xneti->xni_rxring, j);
 			if (j)
 				do_event = 1;
 			/* now we can free the mbufs */
 			for (j = 0; j < i; j++) {
 				m_freem(mbufs_sent[j]);
+			}
 			for (j = 0; j < nppitems; j++) {
 				pool_cache_put_paddr(xmit_pages_cachep,
 				    (void *)pages_pool_free[j].va,
 				    pages_pool_free[j].pa);
+			}
+		}
 		/* send event */
 		if (do_event) {
 			x86_lfence();
 			XENPRINTF(("%s receive event\n",
 			    xneti->xni_if.if_xname));
 			hypervisor_notify_via_evtchn(xneti->xni_evtchn);
 			do_event = 0;
+		}
 		/* check if we need to get back some pages */
 		if (mcl_pages_alloc < 0) {
 			xennetback_get_new_mcl_pages();
 			if (mcl_pages_alloc < 0) {
 				/*
 				 * setup the watchdog to try again, because
 				 * xennetback_ifstart() will never be called
 				 * again if queue is full.
 				 */
 				printf("xennetback_ifstart: no mcl_pages\n");
 				ifp->if_timer = 1;
 				break;
+			}
+		}
 		/*
 		 * note that we don't use RING_FINAL_CHECK_FOR_REQUESTS()
 		 * here, as the frontend doesn't notify when adding
 		 * requests anyway
 		 */
 		if (__predict_false(
 		    !RING_HAS_UNCONSUMED_REQUESTS(&xneti->xni_rxring))) {
 			/* ring full */
 			break;
+		}
+	}
 	splx(s);
+}
 static void
 xennetback_ifsoftstart_copy(void *arg)
+{
 	struct xnetback_instance *xneti = arg;
 	struct ifnet *ifp = &xneti->xni_if;
 	struct mbuf *m, *new_m;
 	paddr_t xmit_pa;
 	paddr_t xmit_ma;
 	int i, j;
 	netif_rx_response_t *rxresp;
 	RING_IDX req_prod, resp_prod;
 	int do_event = 0;
 	gnttab_copy_t *gop;
 	int id, offset;
 	XENPRINTF(("xennetback_ifsoftstart_transfer "));
 	int s = splnet();
 	if (__predict_false(
 	    (ifp->if_flags & (IFF_RUNNING|IFF_OACTIVE)) != IFF_RUNNING)) {
 		splx(s);
 		return;
+	}
 	while (!IFQ_IS_EMPTY(&ifp->if_snd)) {
 		XENPRINTF(("pkt\n"));
 		req_prod = xneti->xni_rxring.sring->req_prod;
 		resp_prod = xneti->xni_rxring.rsp_prod_pvt;
 		xen_rmb();
 		gop = xstart_gop_copy;
 		for (i = 0; !IFQ_IS_EMPTY(&ifp->if_snd);) {
 			XENPRINTF(("have a packet\n"));
 			IFQ_POLL(&ifp->if_snd, m);
 			if (__predict_false(m == NULL))
 				panic("xennetback_ifstart: IFQ_POLL");
 			if (__predict_false(
 			    req_prod == xneti->xni_rxring.req_cons ||
 			    xneti->xni_rxring.req_cons - resp_prod ==
 			    NET_RX_RING_SIZE)) {
 				/* out of ring space */
 				XENPRINTF(("xennetback_ifstart: ring full "
 				    "req_prod 0x%x req_cons 0x%x resp_prod "
 				    "0x%x\n",
 				    req_prod, xneti->xni_rxring.req_cons,
 				    resp_prod));
 				ifp->if_timer = 1;
 				break;
+			}
 			if (__predict_false(i == NB_XMIT_PAGES_BATCH))
 				break; /* we filled the array */
 			switch (m->m_flags & (M_EXT|M_EXT_CLUSTER)) {
 			case M_EXT|M_EXT_CLUSTER:
 				KASSERT(m->m_ext.ext_paddr != M_PADDR_INVALID);
 				xmit_pa = m->m_ext.ext_paddr;
 				offset = m->m_data - m->m_ext.ext_buf;
 				break;
 			case 0:
 				KASSERT(m->m_paddr != M_PADDR_INVALID);
 				xmit_pa = m->m_paddr;
 				offset = M_BUFOFFSET(m) +
 				    (m->m_data - M_BUFADDR(m));
 				break;
 			default:
 				if (__predict_false(
 				    !pmap_extract(pmap_kernel(),
 				    (vaddr_t)m->m_data, &xmit_pa))) {
 					panic("xennet_start: no pa");
+				}
 				offset = 0;
 				break;
+			}
 			offset += (xmit_pa & ~PG_FRAME);
 			xmit_pa = (xmit_pa & PG_FRAME);
 			if (m->m_pkthdr.len != m->m_len ||
 			    (offset + m->m_pkthdr.len) > PAGE_SIZE) {
 				MGETHDR(new_m, M_DONTWAIT, MT_DATA);
 				if (__predict_false(new_m == NULL)) {
 					printf("%s: cannot allocate new mbuf\n",
 					    ifp->if_xname);
 					break;
+				}
 				if (m->m_pkthdr.len > MHLEN) {
 					MCLGET(new_m, M_DONTWAIT);
 					if (__predict_false(
 					    (new_m->m_flags & M_EXT) == 0)) {
 						XENPRINTF((
 						    "%s: no mbuf cluster\n",
 						    ifp->if_xname));
 						m_freem(new_m);
 						break;
+					}
 					xmit_pa = new_m->m_ext.ext_paddr;
 					offset = new_m->m_data -
 					    new_m->m_ext.ext_buf;
 				} else {
 					xmit_pa = new_m->m_paddr;
 					offset = M_BUFOFFSET(new_m) +
 					    (new_m->m_data - M_BUFADDR(new_m));
+				}
 				offset += (xmit_pa & ~PG_FRAME);
 				xmit_pa = (xmit_pa & PG_FRAME);
 				m_copydata(m, 0, m->m_pkthdr.len,
 				    mtod(new_m, void *));
 				new_m->m_len = new_m->m_pkthdr.len =
 				    m->m_pkthdr.len;
 				IFQ_DEQUEUE(&ifp->if_snd, m);
 				m_freem(m);
 				m = new_m;
 			} else {
 				IFQ_DEQUEUE(&ifp->if_snd, m);
+			}
 			KASSERT(xmit_pa != POOL_PADDR_INVALID);
 			KASSERT((offset + m->m_pkthdr.len) <= PAGE_SIZE);
 			xmit_ma = xpmap_ptom(xmit_pa);
 			/* start filling ring */
 			gop->flags = GNTCOPY_dest_gref;
 			gop->source.offset = offset;
 			gop->source.domid = DOMID_SELF;
 			gop->source.u.gmfn = xmit_ma >> PAGE_SHIFT;
 			gop->dest.u.ref = RING_GET_REQUEST(&xneti->xni_rxring,
 			    xneti->xni_rxring.req_cons)->gref;
 			gop->dest.offset = 0;
 			gop->dest.domid = xneti->xni_domid;
 			gop->len = m->m_pkthdr.len;
 			gop++;
 			id = RING_GET_REQUEST(&xneti->xni_rxring,
 			    xneti->xni_rxring.req_cons)->id;
 			xen_rmb();
 			xneti->xni_rxring.req_cons++;
 			rxresp = RING_GET_RESPONSE(&xneti->xni_rxring,
 			    resp_prod);
 			rxresp->id = id;
 			rxresp->offset = 0;
 			rxresp->status = m->m_pkthdr.len;
 			if ((m->m_pkthdr.csum_flags &
 			    (M_CSUM_TCPv4 | M_CSUM_UDPv4)) != 0) {
 				rxresp->flags = NETRXF_csum_blank;
 			} else {
 				rxresp->flags = 0;
+			}
 			mbufs_sent[i] = m;
 			resp_prod++;
 			i++; /* this packet has been queued */
 			ifp->if_opackets++;
 #if NBPFILTER > 0
 			if (ifp->if_bpf)
 				bpf_mtap(ifp->if_bpf, m);
 #endif
+		}
 		if (i != 0) {
 			if (HYPERVISOR_grant_table_op(GNTTABOP_copy,
 			    xstart_gop_copy, i) != 0) {
 				panic("%s: GNTTABOP_copy failed",
 				    ifp->if_xname);
+			}
 			for (j = 0; j < i; j++) {
 				if (xstart_gop_copy[j].status != GNTST_okay) {
 					printf("%s GNTTABOP_copy[%d] %d\n",
 					    ifp->if_xname,
 					    j, xstart_gop_copy[j].status);
 					printf("%s: req_prod %u req_cons "
 					    "%u rsp_prod %u rsp_prod_pvt %u "
 					    "i %d\n",
 					    ifp->if_xname,
 					    xneti->xni_rxring.sring->req_prod,
 					    xneti->xni_rxring.req_cons,
 					    xneti->xni_rxring.sring->rsp_prod,
 					    xneti->xni_rxring.rsp_prod_pvt,
 					    i);
 					rxresp = RING_GET_RESPONSE(
 					    &xneti->xni_rxring,
 					    xneti->xni_rxring.rsp_prod_pvt + j);
 					rxresp->status = NETIF_RSP_ERROR;
+				}
+			}
 			/* update pointer */
 			KASSERT(
 			    xneti->xni_rxring.rsp_prod_pvt + i == resp_prod);
 			xneti->xni_rxring.rsp_prod_pvt = resp_prod;
 			RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
 			    &xneti->xni_rxring, j);
 			if (j)
 				do_event = 1;
 			/* now we can free the mbufs */
 			for (j = 0; j < i; j++) {
 				m_freem(mbufs_sent[j]);
+			}
+		}
 		/* send event */
 		if (do_event) {
 			xen_rmb();
 			XENPRINTF(("%s receive event\n",
 			    xneti->xni_if.if_xname));
 			hypervisor_notify_via_evtchn(xneti->xni_evtchn);
 			do_event = 0;
+		}
 		/*
 		 * note that we don't use RING_FINAL_CHECK_FOR_REQUESTS()
 		 * here, as the frontend doesn't notify when adding
 		 * requests anyway
 		 */
 		if (__predict_false(
 		    !RING_HAS_UNCONSUMED_REQUESTS(&xneti->xni_rxring))) {
 			/* ring full */
 			break;
+		}
+	}
 	splx(s);
+}
 static void
 xennetback_ifwatchdog(struct ifnet * ifp)
+{
 	/*
 	 * We can get to the following condition:
 	 * transmit stalls because the ring is full when the ifq is full too.
 	 * In this case (as, unfortunably, we don't get an interrupt from xen
 	 * on transmit) noting will ever call xennetback_ifstart() again.
 	 * Here we abuse the watchdog to get out of this condition.
 	 */
 	XENPRINTF(("xennetback_ifwatchdog\n"));
 	xennetback_ifstart(ifp);
+}
 static int
 xennetback_ifinit(struct ifnet *ifp)
+{
 	struct xnetback_instance *xneti = ifp->if_softc;
 	int s = splnet();
 	if ((ifp->if_flags & IFF_UP) == 0) {
 		splx(s);
 		return 0;
+	}
 	if (xneti->xni_status == CONNECTED)
 		ifp->if_flags |= IFF_RUNNING;
 	splx(s);
 	return 0;
+}
 static void
 xennetback_ifstop(struct ifnet *ifp, int disable)
+{
 	struct xnetback_instance *xneti = ifp->if_softc;
 	int s = splnet();
 	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
 	ifp->if_timer = 0;
 	if (xneti->xni_status == CONNECTED) {
 		XENPRINTF(("%s: req_prod 0x%x resp_prod 0x%x req_cons 0x%x "
 		    "event 0x%x\n", ifp->if_xname, xneti->xni_txring->req_prod,
 		    xneti->xni_txring->resp_prod, xneti->xni_txring->req_cons,
 		    xneti->xni_txring->event));
 		xennetback_evthandler(ifp->if_softc); /* flush pending RX requests */
+	}
 	splx(s);
+}