經(jīng)過前面兩篇博文的分析，已經(jīng)對Linux的內(nèi)核網(wǎng)絡棧的結構有了一個模糊的認識，這里我們開始從底層開始詳細分析Linux內(nèi)核網(wǎng)絡棧的實現(xiàn)。由于這是早期版本，代碼的層次隔離做的還不是很好，這里說是從底層分析，但是不免會牽扯上層或下層的函數(shù)，許多關鍵代碼都在驅動的文件夾下。

我們首先有第一篇博文中知道在網(wǎng)絡棧初始化的時候在net/socket.c中的函數(shù)sock_init()函數(shù)中當proto_init()完成后會執(zhí)行dev_init()來進行網(wǎng)絡設備模塊的初始化。

首先說明一下，在drivers/net/space.c中定義了設備首節(jié)點地址dev_base，其實際上是回環(huán)設備的地址。

structdevice?loopback_dev?=?{

"lo",/*?Software?Loopback?interface??????*/

0x0,/*?recv?memory?end??????????*/

0x0,/*?recv?memory?start????????????*/

0x0,/*?memory?end???????????????*/

0x0,/*?memory?start?????????????*/

0,/*?base?I/O?address?????????*/

0,/*?IRQ??????????????????*/

0,?0,?0,/*?flags????????????????*/

NEXT_DEV,/*?next?device??????????????*/

loopback_init/*?loopback_init?should?set?up?the?rest?*/

};

structdevice?*dev_base?=?&loopback_dev;而NEXT_DEV宏定義即定義了下一個網(wǎng)絡設備的地址，這樣可以把設備串成鏈。

附網(wǎng)絡設備的定義(include/linux/netdevice.h)如下:

/*

*?The?DEVICE?structure.

*?Actually,?this?whole?structure?is?a?big?mistake.??It?mixes?I/O

*?data?with?strictly?"high-level"?data,?and?it?has?to?know?about

*?almost?every?data?structure?used?in?the?INET?module.

*/

structdevice

{

/*

*?This?is?the?first?field?of?the?"visible"?part?of?this?structure

*?(i.e.?as?seen?by?users?in?the?"Space.c"?file).??It?is?the?name

*?the?interface.

*/

char*name;

/*?I/O?specific?fields?-?FIXME:?Merge?these?and?struct?ifmap?into?one?*/

unsignedlongrmem_end;/*?shmem?"recv"?end?*/

unsignedlongrmem_start;/*?shmem?"recv"?start???*/

unsignedlongmem_end;/*?sahared?mem?end??*/

unsignedlongmem_start;/*?shared?mem?start?*/

unsignedlongbase_addr;/*?device?I/O?address???*/

unsignedcharirq;/*?device?IRQ?number????*/

/*?Low-level?status?flags.?*/

volatileunsignedcharstart,/*?start?an?operation???*/

tbusy,/*?transmitter?busy?*/

interrupt;/*?interrupt?arrived????*/

structdevice???????*next;

/*?The?device?initialization?function.?Called?only?once.?*/

int(*init)(structdevice?*dev);

/*?Some?hardware?also?needs?these?fields,?but?they?are?not?part?of?the

usual?set?specified?in?Space.c.?*/

unsignedcharif_port;/*?Selectable?AUI,?TP,..*/

unsignedchardma;/*?DMA?channel??????*/

structenet_statistics*?(*get_stats)(structdevice?*dev);

/*

*?This?marks?the?end?of?the?"visible"?part?of?the?structure.?All

*?fields?hereafter?are?internal?to?the?system,?and?may?change?at

*?will?(read:?may?be?cleaned?up?at?will).

*/

/*?These?may?be?needed?for?future?network-power-down?code.?*/

unsignedlongtrans_start;/*?Time?(in?jiffies)?of?last?Tx?*/

unsignedlonglast_rx;/*?Time?of?last?Rx??????*/

unsignedshortflags;/*?interface?flags?(a?la?BSD)???*/

unsignedshortfamily;/*?address?family?ID?(AF_INET)??*/

unsignedshortmetric;/*?routing?metric?(not?used)????*/

unsignedshortmtu;/*?interface?MTU?value??????*/

unsignedshorttype;/*?interface?hardware?type??*/

unsignedshorthard_header_len;/*?hardware?hdr?length??*/

void*priv;/*?pointer?to?private?data??*/

/*?Interface?address?info.?*/

unsignedcharbroadcast[MAX_ADDR_LEN];/*?hw?bcast?add?*/

unsignedchardev_addr[MAX_ADDR_LEN];/*?hw?address???*/

unsignedcharaddr_len;/*?hardware?address?length??*/

unsignedlongpa_addr;/*?protocol?address?????*/

unsignedlongpa_brdaddr;/*?protocol?broadcast?addr??*/

unsignedlongpa_dstaddr;/*?protocol?P-P?other?side?addr?*/

unsignedlongpa_mask;/*?protocol?netmask?????*/

unsignedshortpa_alen;/*?protocol?address?length??*/

structdev_mc_list?????*mc_list;/*?Multicast?mac?addresses??*/

intmc_count;/*?Number?of?installed?mcasts???*/

structip_mc_list??*ip_mc_list;/*?IP?multicast?filter?chain????*/

/*?For?load?balancing?driver?pair?support?*/

unsignedlongpkt_queue;/*?Packets?queued?*/

structdevice???????*slave;/*?Slave?device?*/

/*?Pointer?to?the?interface?buffers.?*/

structsk_buff_head?????buffs[DEV_NUMBUFFS];

/*?Pointers?to?interface?service?routines.?*/

int(*open)(structdevice?*dev);

int(*stop)(structdevice?*dev);

int(*hard_start_xmit)?(structsk_buff?*skb,

structdevice?*dev);

int(*hard_header)?(unsignedchar*buff,

structdevice?*dev,

unsignedshorttype,

void*daddr,

void*saddr,

unsigned?len,

structsk_buff?*skb);

int(*rebuild_header)(void*eth,structdevice?*dev,

unsignedlongraddr,structsk_buff?*skb);

unsignedshort(*type_trans)?(structsk_buff?*skb,

structdevice?*dev);

#define?HAVE_MULTICAST

void(*set_multicast_list)(structdevice?*dev,

intnum_addrs,void*addrs);

#define?HAVE_SET_MAC_ADDR

int(*set_mac_address)(structdevice?*dev,void*addr);

#define?HAVE_PRIVATE_IOCTL

int(*do_ioctl)(structdevice?*dev,structifreq?*ifr,intcmd);

#define?HAVE_SET_CONFIG

int(*set_config)(structdevice?*dev,structifmap?*map);

};dev_init()網(wǎng)絡設備的初始化函數(shù)如下：

/*

*??Initialize?the?DEV?module.?At?boot?time?this?walks?the?device?list?and

*??unhooks?any?devices?that?fail?to?initialise?(normally?hardware?not

*??present)?and?leaves?us?with?a?valid?list?of?present?and?active?devices.

*

*??The?PCMCIA?code?may?need?to?change?this?a?little,?and?add?a?pair

*??of?register_inet_device()?unregister_inet_device()?calls.?This?will?be

*??needed?for?ethernet?as?modules?support.

*/

voiddev_init(void)

{

structdevice?*dev,?*dev2;

/*

*??Add?the?devices.

*??If?the?call?to?dev->init?fails,?the?dev?is?removed

*??from?the?chain?disconnecting?the?device?until?the

*??next?reboot.

*/

dev2?=?NULL;

for(dev?=?dev_base;?dev?!=?NULL;?dev=dev->next)//循環(huán)移除設備由璞傅絛ev_base指向的網(wǎng)絡設備鏈表

{

if(dev->init?&&?dev->init(dev))//如果設備有初始化函數(shù)并且初始化失敗，則從鏈表摘除設備(init()函數(shù)成功返回0)

{

/*

*??It?failed?to?come?up.?Unhook?it.這個函數(shù)還挺有技巧性的，從默認配置的設備中掃描不存在的設備，將其移除

*/

if(dev2?==?NULL)

dev_base?=?dev->next;

else

dev2->next?=?dev->next;

}

else

{

dev2?=?dev;

}

}

}這里我們看一下dev_base這個隊列是如何定義的，這里我們僅僅看eth網(wǎng)卡的定義方式即可

/*?"eth0"?defaults?to?autoprobe?(==?0),?other?use?a?base?of?0xffe0?(==?-0x20),

which?means?"don't?probe".??These?entries?exist?to?only?to?provide?empty

slots?which?may?be?enabled?at?boot-time.?*/

staticstructdevice?eth3_dev?=?{

"eth3",?0,0,0,0,0xffe0/*?I/O?base*/,?0,0,0,0,?NEXT_DEV,?ethif_probe?};

staticstructdevice?eth2_dev?=?{

"eth2",?0,0,0,0,0xffe0/*?I/O?base*/,?0,0,0,0,?e3_dev,?ethif_probe?};

staticstructdevice?eth1_dev?=?{

"eth1",?0,0,0,0,0xffe0/*?I/O?base*/,?0,0,0,0,?e2_dev,?ethif_probe?};

staticstructdevice?eth0_dev?=?{

"eth0",?0,?0,?0,?0,?ETH0_ADDR,?ETH0_IRQ,?0,?0,?0,?e1_dev,?ethif_probe?};

#???undef?NEXT_DEV

#???define?NEXT_DEV?(e0_dev)可以看出eth系列網(wǎng)卡設備的init函數(shù)定義為ethif_probe()，該函數(shù)會調(diào)用具體網(wǎng)卡的探測函數(shù)，我們還是以?NS8390 ethernet網(wǎng)卡為例來分析，該網(wǎng)卡的驅動實現(xiàn)文件為drivers/net/ne.c

ethif_probe()函數(shù)會調(diào)用函數(shù)ne_probe()探測函數(shù)，而該函數(shù)對設備地址進行檢查后調(diào)用ne_probe1()函數(shù)，具體工作有ne_probe1()函數(shù)完成。

函數(shù)如下：

staticintne_probe1(structdevice?*dev,intioaddr)

{

.....................//合法性檢查

/*?Fixup?for?users?that?don't?know?that?IRQ?2?is?really?IRQ?9,

or?don't?know?which?one?to?set.?*/

dev->irq?=?9;//設置中斷類型號

/*?Snarf?the?interrupt?now.??There's?no?point?in?waiting?since?we?cannot

share?and?the?board?will?usually?be?enabled.?*/

{

intirqval?=?request_irq?(dev->irq,?ei_interrupt,?0,?wordlength==2??"ne2000":"ne1000");//注冊申請中斷，中斷處理函數(shù)為ei_interrupt

if(irqval)?{

printk?("?unable?to?get?IRQ?%d?(irqval=%d).\n",?dev->irq,?irqval);

returnEAGAIN;

}

}

dev->base_addr?=?ioaddr;

request_region(ioaddr,?NE_IO_EXTENT,?wordlength==2??"ne2000":"ne1000");//申請內(nèi)存空間

for(i?=?0;?i?

dev->dev_addr[i]?=?SA_prom[i];

ethdev_init(dev);//調(diào)用函數(shù)對dev設備結構體進行初始化

printk("\n%s:?%s?found?at?%#x,?using?IRQ?%d.\n",

dev->name,?name,?ioaddr,?dev->irq);

if(ei_debug?>?0)

printk(version);

ei_status.name?=?name;

ei_status.tx_start_page?=?start_page;

ei_status.stop_page?=?stop_page;

ei_status.word16?=?(wordlength?==?2);

ei_status.rx_start_page?=?start_page?+?TX_PAGES;

#ifdef?PACKETBUF_MEMSIZE

/*?Allow?the?packet?buffer?size?to?be?overridden?by?know-it-alls.?*/

ei_status.stop_page?=?ei_status.tx_start_page?+?PACKETBUF_MEMSIZE;

#endif

ei_status.reset_8390?=?&ne_reset_8390;

ei_status.block_input?=?&ne_block_input;

ei_status.block_output?=?&ne_block_output;

NS8390_init(dev,?0);//配置網(wǎng)卡中的寄存器等到默認狀態(tài)

return0;

}初始化函數(shù)ethdev_init()在文件drivers/net/8390.c中。如下：

/*?Initialize?the?rest?of?the?8390?device?structure.?*/

intethdev_init(structdevice?*dev)

{

if(ei_debug?>?1)

printk(version);

if(dev->priv?==?NULL)?{//申請私有空間存儲具體網(wǎng)卡的結構體信息

structei_device?*ei_local;//8390網(wǎng)卡設備的結構體

dev->priv?=?kmalloc(sizeof(structei_device),?GFP_KERNEL);//申請內(nèi)核內(nèi)存空間

memset(dev->priv,?0,sizeof(structei_device));

ei_local?=?(structei_device?*)dev->priv;

#ifndef?NO_PINGPONG

ei_local->pingpong?=?1;

#endif

}

/*?The?open?call?may?be?overridden?by?the?card-specific?code.?*/

if(dev->open?==?NULL)

dev->open?=?&ei_open;//設備的打開函數(shù)

/*?We?should?have?a?dev->stop?entry?also.?*/

dev->hard_start_xmit?=?&ei_start_xmit;//設備的發(fā)送函數(shù)，定義在8390.c中

dev->get_stats???=?get_stats;

#ifdef?HAVE_MULTICAST

dev->set_multicast_list?=?&set_multicast_list;

#endif

ether_setup(dev);//進一步調(diào)用函數(shù)設置dev設備結構體

return0;

}ether_setup()函數(shù)的實現(xiàn)如下：

voidether_setup(structdevice?*dev)

{

inti;

/*?Fill?in?the?fields?of?the?device?structure?with?ethernet-generic?values.

This?should?be?in?a?common?file?instead?of?per-driver.??*/

for(i?=?0;?i?

skb_queue_head_init(&dev->buffs[i]);//緩沖隊列初始化

/*?register?boot-defined?"eth"?devices?*/

if(dev->name?&&?(strncmp(dev->name,"eth",?3)?==?0))?{//定義eth網(wǎng)卡的名稱

i?=?simple_strtoul(dev->name?+?3,?NULL,?0);

if(ethdev_index[i]?==?NULL)?{

ethdev_index[i]?=?dev;

}

elseif(dev?!=?ethdev_index[i])?{

/*?Really?shouldn't?happen!?*/

printk("ether_setup:?Ouch!?Someone?else?took?%s\n",

dev->name);

}

}

dev->hard_header?=?eth_header;//該函數(shù)的作用是創(chuàng)建鏈路層首部，定義在eth.c中

dev->rebuild_header?=?eth_rebuild_header;//該函數(shù)的作用是重建鏈路層首部，用于ARP協(xié)議

dev->type_trans?=?eth_type_trans;

dev->type????????=?ARPHRD_ETHER;

dev->hard_header_len?=?ETH_HLEN;

dev->mtu?????=?1500;/*?eth_mtu?*/

dev->addr_len????=?ETH_ALEN;

for(i?=?0;?i?

dev->broadcast[i]=0xff;

}

/*?New-style?flags.?*/

dev->flags???????=?IFF_BROADCAST|IFF_MULTICAST;

dev->family??????=?AF_INET;

dev->pa_addr?=?0;

dev->pa_brdaddr?=?0;

dev->pa_mask?=?0;

dev->pa_alen?=sizeof(unsignedlong);

}這樣，網(wǎng)絡設備的初始化工作就完成了。

在drivers/net/8390.c中實現(xiàn)了該網(wǎng)卡的設備的基本操作函數(shù)，

設備的打開函數(shù)ei_open()比較簡單，下面列出該設備的發(fā)送和接收函數(shù)，在這里不做具體的分析，如果想更多了解請點擊前面分析過的DM9000網(wǎng)卡驅動，下面給出鏈接：

ei_start_xmit()

staticintei_start_xmit(structsk_buff?*skb,structdevice?*dev)

{

inte8390_base?=?dev->base_addr;

structei_device?*ei_local?=?(structei_device?*)?dev->priv;

intlength,?send_length;

unsignedlongflags;

/*

*??We?normally?shouldn't?be?called?if?dev->tbusy?is?set,?but?the

*??existing?code?does?anyway.?If?it?has?been?too?long?since?the

*??last?Tx,?we?assume?the?board?has?died?and?kick?it.

*/

if(dev->tbusy)?{/*?Do?timeouts,?just?like?the?8003?driver.?*/

inttxsr?=?inb(e8390_base+EN0_TSR),?isr;

inttickssofar?=?jiffies?-?dev->trans_start;

if(tickssofar?

return1;

}

isr?=?inb(e8390_base+EN0_ISR);

if(dev->start?==?0)?{

printk("%s:?xmit?on?stopped?card\n",?dev->name);

return1;

}

printk(KERN_DEBUG"%s:?transmit?timed?out,?TX?status?%#2x,?ISR?%#2x.\n",

dev->name,?txsr,?isr);

/*?Does?the?8390?thinks?it?has?posted?an?interrupt??*/

if(isr)

printk(KERN_DEBUG"%s:?Possible?IRQ?conflict?on?IRQ%d?\n",?dev->name,?dev->irq);

else{

/*?The?8390?probably?hasn't?gotten?on?the?cable?yet.?*/

printk(KERN_DEBUG"%s:?Possible?network?cable?problem?\n",?dev->name);

if(ei_local->stat.tx_packets==0)

ei_local->interface_num?^=?1;/*?Try?a?different?xcvr.??*/

}

/*?Try?to?restart?the?card.??Perhaps?the?user?has?fixed?something.?*/

ei_reset_8390(dev);

NS8390_init(dev,?1);

dev->trans_start?=?jiffies;

}

/*?Sending?a?NULL?skb?means?some?higher?layer?thinks?we've?missed?an

tx-done?interrupt.?Caution:?dev_tint()?handles?the?cli()/sti()

itself.?*/

if(skb?==?NULL)?{

dev_tint(dev);

return0;

}

length?=?skb->len;

if(skb->len?<=?0)

return0;

save_flags(flags);

cli();

/*?Block?a?timer-based?transmit?from?overlapping.?*/

if((set_bit(0,?(void*)&dev->tbusy)?!=?0)?||?ei_local->irqlock)?{

printk("%s:?Tx?access?conflict.?irq=%d?lock=%d?tx1=%d?tx2=%d?last=%d\n",

dev->name,?dev->interrupt,?ei_local->irqlock,?ei_local->tx1,

ei_local->tx2,?ei_local->lasttx);

restore_flags(flags);

return1;

}

/*?Mask?interrupts?from?the?ethercard.?*/

outb(0x00,?e8390_base?+?EN0_IMR);

ei_local->irqlock?=?1;

restore_flags(flags);

send_length?=?ETH_ZLEN?

if(ei_local->pingpong)?{

intoutput_page;

if(ei_local->tx1?==?0)?{

output_page?=?ei_local->tx_start_page;

ei_local->tx1?=?send_length;

if(ei_debug??&&??ei_local->tx2?>?0)

printk("%s:?idle?transmitter?tx2=%d,?lasttx=%d,?txing=%d.\n",

dev->name,?ei_local->tx2,?ei_local->lasttx,

ei_local->txing);

}elseif(ei_local->tx2?==?0)?{

output_page?=?ei_local->tx_start_page?+?6;

ei_local->tx2?=?send_length;

if(ei_debug??&&??ei_local->tx1?>?0)

printk("%s:?idle?transmitter,?tx1=%d,?lasttx=%d,?txing=%d.\n",

dev->name,?ei_local->tx1,?ei_local->lasttx,

ei_local->txing);

}else{/*?We?should?never?get?here.?*/

if(ei_debug)

printk("%s:?No?Tx?buffers?free.?irq=%d?tx1=%d?tx2=%d?last=%d\n",

dev->name,?dev->interrupt,?ei_local->tx1,

ei_local->tx2,?ei_local->lasttx);

ei_local->irqlock?=?0;

dev->tbusy?=?1;

outb_p(ENISR_ALL,?e8390_base?+?EN0_IMR);

return1;

}

ei_block_output(dev,?length,?skb->data,?output_page);

if(!?ei_local->txing)?{

ei_local->txing?=?1;

NS8390_trigger_send(dev,?send_length,?output_page);

dev->trans_start?=?jiffies;

if(output_page?==?ei_local->tx_start_page)

ei_local->tx1?=?-1,?ei_local->lasttx?=?-1;

else

ei_local->tx2?=?-1,?ei_local->lasttx?=?-2;

}else

ei_local->txqueue++;

dev->tbusy?=?(ei_local->tx1??&&??ei_local->tx2);

}else{/*?No?pingpong,?just?a?single?Tx?buffer.?*/

ei_block_output(dev,?length,?skb->data,?ei_local->tx_start_page);

ei_local->txing?=?1;

NS8390_trigger_send(dev,?send_length,?ei_local->tx_start_page);

dev->trans_start?=?jiffies;

dev->tbusy?=?1;

}

/*?Turn?8390?interrupts?back?on.?*/

ei_local->irqlock?=?0;

outb_p(ENISR_ALL,?e8390_base?+?EN0_IMR);

dev_kfree_skb?(skb,?FREE_WRITE);

return0;

}ei_receive()函數(shù)

staticvoidei_receive(structdevice?*dev)

{

inte8390_base?=?dev->base_addr;

structei_device?*ei_local?=?(structei_device?*)?dev->priv;

intrxing_page,?this_frame,?next_frame,?current_offset;

intrx_pkt_count?=?0;

structe8390_pkt_hdr?rx_frame;

intnum_rx_pages?=?ei_local->stop_page-ei_local->rx_start_page;

while(++rx_pkt_count?

intpkt_len;

/*?Get?the?rx?page?(incoming?packet?pointer).?*/

outb_p(E8390_NODMA+E8390_PAGE1,?e8390_base?+?E8390_CMD);

rxing_page?=?inb_p(e8390_base?+?EN1_CURPAG);

outb_p(E8390_NODMA+E8390_PAGE0,?e8390_base?+?E8390_CMD);

/*?Remove?one?frame?from?the?ring.??Boundary?is?always?a?page?behind.?*/

this_frame?=?inb_p(e8390_base?+?EN0_BOUNDARY)?+?1;

if(this_frame?>=?ei_local->stop_page)

this_frame?=?ei_local->rx_start_page;

/*?Someday?we'll?omit?the?previous,?iff?we?never?get?this?message.

(There?is?at?least?one?clone?claimed?to?have?a?problem.)??*/

if(ei_debug?>?0??&&??this_frame?!=?ei_local->current_page)

printk("%s:?mismatched?read?page?pointers?%2x?vs?%2x.\n",

dev->name,?this_frame,?ei_local->current_page);

if(this_frame?==?rxing_page)/*?Read?all?the?frames??*/

break;/*?Done?for?now?*/

current_offset?=?this_frame?<

ei_block_input(dev,sizeof(rx_frame),?(char*)&rx_frame,

current_offset);

pkt_len?=?rx_frame.count?-sizeof(rx_frame);

next_frame?=?this_frame?+?1?+?((pkt_len+4)>>8);

/*?Check?for?bogosity?warned?by?3c503?book:?the?status?byte?is?never

written.??This?happened?a?lot?during?testing!?This?code?should?be

cleaned?up?someday.?*/

if(rx_frame.next?!=?next_frame

&&?rx_frame.next?!=?next_frame?+?1

&&?rx_frame.next?!=?next_frame?-?num_rx_pages

&&?rx_frame.next?!=?next_frame?+?1?-?num_rx_pages)?{

ei_local->current_page?=?rxing_page;

outb(ei_local->current_page-1,?e8390_base+EN0_BOUNDARY);

ei_local->stat.rx_errors++;

continue;

}

if(pkt_len??1518)?{

if(ei_debug)

printk("%s:?bogus?packet?size:?%d,?status=%#2x?nxpg=%#2x.\n",

dev->name,?rx_frame.count,?rx_frame.status,

rx_frame.next);

ei_local->stat.rx_errors++;

}elseif((rx_frame.status?&?0x0F)?==?ENRSR_RXOK)?{

structsk_buff?*skb;

skb?=?alloc_skb(pkt_len,?GFP_ATOMIC);

if(skb?==?NULL)?{

if(ei_debug?>?1)

printk("%s:?Couldn't?allocate?a?sk_buff?of?size?%d.\n",

dev->name,?pkt_len);

ei_local->stat.rx_dropped++;

break;

}else{

skb->len?=?pkt_len;

skb->dev?=?dev;

ei_block_input(dev,?pkt_len,?(char*)?skb->data,

current_offset?+sizeof(rx_frame));

netif_rx(skb);

ei_local->stat.rx_packets++;

}

}else{

interrs?=?rx_frame.status;

if(ei_debug)

printk("%s:?bogus?packet:?status=%#2x?nxpg=%#2x?size=%d\n",

dev->name,?rx_frame.status,?rx_frame.next,

rx_frame.count);

if(errs?&?ENRSR_FO)

ei_local->stat.rx_fifo_errors++;

}

next_frame?=?rx_frame.next;

/*?This?_should_?never?happen:?it's?here?for?avoiding?bad?clones.?*/

if(next_frame?>=?ei_local->stop_page)?{

printk("%s:?next?frame?inconsistency,?%#2x\n",?dev->name,

next_frame);

next_frame?=?ei_local->rx_start_page;

}

ei_local->current_page?=?next_frame;

outb_p(next_frame-1,?e8390_base+EN0_BOUNDARY);

}

/*?If?any?worth-while?packets?have?been?received,?dev_rint()

has?done?a?mark_bh(NET_BH)?for?us?and?will?work?on?them

when?we?get?to?the?bottom-half?routine.?*/

/*?Record?the?maximum?Rx?packet?queue.?*/

if(rx_pkt_count?>?high_water_mark)

high_water_mark?=?rx_pkt_count;

/*?Bug?alert!??Reset?ENISR_OVER?to?avoid?spurious?overruns!?*/

outb_p(ENISR_RX+ENISR_RX_ERR+ENISR_OVER,?e8390_base+EN0_ISR);

return;

}

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