Netmap分析（四）

妖狐艹你老母 2022-08-21 07:48 200阅读 0赞

## netmap.c ##

#### NIOCGINFO ####

用于返回netmap的基本信息

case NIOCGINFO:		/* return capabilities etc */
    		if (nmr->nr_cmd == NETMAP_BDG_LIST) {
    			error = netmap_bdg_ctl(nmr, NULL);
    			break;
    		}
    
    		NMG_LOCK();
    		do {
    			/* memsize is always valid */
    			struct netmap_mem_d *nmd = &nm_mem;
    			u_int memflags;
    
    			if (nmr->nr_name[0] != '\0') {
    
    				/* get a refcount */
    /*
    通过nmr得到attach到网卡结构的netmap结构体(netmap adapter)
    */
    				error = netmap_get_na(nmr, &na, &ifp, 1 /* create */);
    				if (error) {
    					na = NULL;
    					ifp = NULL;
    					break;
    				}
    				nmd = na->nm_mem; /* get memory allocator */
    			}
    
    			error = netmap_mem_get_info(nmd, &nmr->nr_memsize, &memflags,
    				&nmr->nr_arg2);
    			if (error)
    				break;
    			if (na == NULL) /* only memory info */
    				break;
    			nmr->nr_offset = 0;
    			nmr->nr_rx_slots = nmr->nr_tx_slots = 0;
    			netmap_update_config(na);
    /* 得到ring的个数，以及每个ring有多少slot */
    			nmr->nr_rx_rings = na->num_rx_rings;
    			nmr->nr_tx_rings = na->num_tx_rings;
    			nmr->nr_rx_slots = na->num_rx_desc;
    			nmr->nr_tx_slots = na->num_tx_desc;
    		} while (0);
    		netmap_unget_na(na, ifp);
    		NMG_UNLOCK();
    		break;

## netmap.c ##

**NIOCREGIF**  
将特定的网卡设置为netmap模式

case NIOCREGIF:
    
    /* possibly attach/detach NIC and VALE switch */
    
    i = nmr->nr_cmd;
    
    if (i == NETMAP_BDG_ATTACH || i == NETMAP_BDG_DETACH
    
    || i == NETMAP_BDG_VNET_HDR
    
    || i == NETMAP_BDG_NEWIF
    
    || i == NETMAP_BDG_DELIF
    
    || i == NETMAP_BDG_POLLING_ON
    
    || i == NETMAP_BDG_POLLING_OFF) {
    
    /*
    
    处理附加网卡、分离网卡、设置netmap adapter、新建虚拟端口、删除虚拟端口、打开polling kthread、关闭polling kthread
    
    */
    
    error = netmap_bdg_ctl(nmr, NULL);
    
    break;
    
    } else if (i == NETMAP_PT_HOST_CREATE || i == NETMAP_PT_HOST_DELETE) {
    
    /*
    
    打开netmap kthread、关闭netmap kthread
    
    */
    
     
    
    error = ptnetmap_ctl(nmr, priv->np_na);
    
    break;
    
    } else if (i == NETMAP_VNET_HDR_GET) {
    
    struct ifnet *ifp;
    
     
    
    NMG_LOCK();
    
    /*
    
    通过nmr得到attach到网卡结构的netmap结构体(netmap adapter)
    
    */
    
    error = netmap_get_na(nmr, &na, &ifp, 0);
    
    if (na && !error) {
    
    nmr->nr_arg1 = na->virt_hdr_len;
    
    }
    
    netmap_unget_na(na, ifp);
    
    NMG_UNLOCK();
    
    break;
    
    } else if (i != 0) {
    
    D("nr_cmd must be 0 not %d", i);
    
    error = EINVAL;
    
    break;
    
    }
    
     
    
    /* protect access to priv from concurrent NIOCREGIF */
    
    NMG_LOCK();
    
    do {
    
    u_int memflags;
    
    struct ifnet *ifp;
    
     
    
    if (priv->np_nifp != NULL) { /* thread already registered */
    
    error = EBUSY;
    
    break;
    
    }
    
    /* find the interface and a reference */
    
    /*
    
    通过nmr得到attach到网卡结构的netmap结构体(netmap adapter)
    
    */
    
     
    
    error = netmap_get_na(nmr, &na, &ifp,
    
          1 /* create */); /* keep reference */
    
    if (error)
    
    break;
    
    if (NETMAP_OWNED_BY_KERN(na)) {
    
    netmap_unget_na(na, ifp);
    
    error = EBUSY;
    
    break;
    
    }
    
     
    
    if (na->virt_hdr_len && !(nmr->nr_flags & NR_ACCEPT_VNET_HDR)) {
    
    netmap_unget_na(na, ifp);
    
    error = EIO;
    
    break;
    
    }
    
     
    
    error = netmap_do_regif(priv, na, nmr->nr_ringid, nmr->nr_flags);
    
    if (error) {    /* reg. failed, release priv and ref */
    
    netmap_unget_na(na, ifp);
    
    break;
    
    }
    
    nifp = priv->np_nifp;
    
    priv->np_td = td; // XXX kqueue, debugging only
    
     
    
    /* return the offset of the netmap_if object */
    
    nmr->nr_rx_rings = na->num_rx_rings;
    
    nmr->nr_tx_rings = na->num_tx_rings;
    
    nmr->nr_rx_slots = na->num_rx_desc;
    
    nmr->nr_tx_slots = na->num_tx_desc;
    
    error = netmap_mem_get_info(na->nm_mem, &nmr->nr_memsize, &memflags,
    
    &nmr->nr_arg2);
    
    if (error) {
    
    netmap_do_unregif(priv);
    
    netmap_unget_na(na, ifp);
    
    break;
    
    }
    
    if (memflags & NETMAP_MEM_PRIVATE) {
    
    *(uint32_t *)(uintptr_t)&nifp->ni_flags |= NI_PRIV_MEM;
    
    }
    
    for_rx_tx(t) {
    
    priv->np_si[t] = nm_si_user(priv, t) ?
    
    &na->si[t] : &NMR(na, t)[priv->np_qfirst[t]].si;
    
    }
    
     
    
    if (nmr->nr_arg3) {
    
    D("requested %d extra buffers", nmr->nr_arg3);
    
    nmr->nr_arg3 = netmap_extra_alloc(na,
    
    &nifp->ni_bufs_head, nmr->nr_arg3);
    
    D("got %d extra buffers", nmr->nr_arg3);
    
    }
    
    nmr->nr_offset = netmap_mem_if_offset(na->nm_mem, nifp);
    
     
    
    /* store ifp reference so that priv destructor may release it */
    
    priv->np_ifp = ifp;
    
    } while (0);
    
    NMG_UNLOCK();
    
    break;