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本附录列出了本书中描述的 Linux 使用的主要的数据结构。为了在页面上访得下，它们经过了少量的编辑。

Block_dev_struct

block_dev_struct 数据结构用于登记可用的块设备，让 buffer cache 使用。它们放在 blk_dev 向量表中。

参见 include/linux/blkdev.h

struct blk_dev_struct {

void (*request_fn)(void);

struct request * current_request;

struct request plug;

struct tq_struct plug_tq;

} ;

buffer_head

buffer_head 数据结构存放 buffer cache 中一个块缓冲区的信息。

参见 include/linux/fs.h

* bh state bits */

#define BH_Uptodate 0 /* 1 if the buffer contains valid data */

#define BH_Dirty 1 /* 1 if the buffer is dirty */

#define BH_Lock 2 /* 1 if the buffer is locked */

#define BH_Req 3 /* 0 if the buffer has been invalidated */

#define BH_Touched 4 /* 1 if the buffer has been touched (aging) */

#define BH_Has_aged 5 /* 1 if the buffer has been aged (aging) */

#define BH_Protected 6 /* 1 if the buffer is protected */

#define BH_FreeOnIO 7 /* 1 to discard the buffer_head after IO */

struct buffer_head {

/* First cache line: */

unsigned long b_blocknr; /* block number */

kdev_t b_dev; /* device (B_FREE = free) */

kdev_t b_rdev; /* Real device */

unsigned long b_rsector; /* Real buffer location on disk */

struct buffer_head *b_next; /* Hash queue list */

struct buffer_head *b_this_page; /* circular list of buffers in one

page */

/* Second cache line: */

unsigned long b_state; /* buffer state bitmap (above) */

struct buffer_head *b_next_free;

unsigned int b_count; /* users using this block */

unsigned long b_size; /* block size */

/* Non-performance-critical data follows. */

char *b_data; /* pointer to data block */

unsigned int b_list; /* List that this buffer appears */

unsigned long b_flushtime; /* Time when this (dirty) buffer

* should be written */

unsigned long b_lru_time; /* Time when this buffer was

* last used. */

struct wait_queue *b_wait;

struct buffer_head *b_prev; /* doubly linked hash list */

struct buffer_head *b_prev_free; /* doubly linked list of buffers */

struct buffer_head *b_reqnext; /* request queue */

} ;

　

device

系统中的每一个网络设备都用一个 device 数据结构表示

参见 include/linux/netdevice.h

struct device

{

/*

* 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 */

unsigned long rmem_end; /* shmem "recv" end */

unsigned long rmem_start; /* shmem "recv" start */

unsigned long mem_end; /* shared mem end */

unsigned long mem_start; /* shared mem start */

unsigned long base_addr; /* device I/O address */

unsigned char irq; /* device IRQ number */

/* Low-level status flags. */

volatile unsigned char start, /* start an operation */

interrupt; /* interrupt arrived */

unsigned long tbusy; /* transmitter busy */

struct device *next;

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

int (*init)(struct device *dev);

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

the usual set specified in Space.c. */

unsigned char if_port; /* Selectable AUI,TP, */

unsigned char dma; /* DMA channel */

struct enet_statistics* (*get_stats)(struct device *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. */

unsigned long trans_start; /* Time (jiffies) of

last transmit */

unsigned long last_rx; /* Time of last Rx */

unsigned short flags; /* interface flags (BSD)*/

unsigned short family; /* address family ID */

unsigned short metric; /* routing metric */

unsigned short mtu; /* MTU value */

unsigned short type; /* hardware type */

unsigned short hard_header_len; /* hardware hdr len */

void *priv; /* private data */

/* Interface address info. */

unsigned char broadcast[MAX_ADDR_LEN];

unsigned char pad;

unsigned char dev_addr[MAX_ADDR_LEN];

unsigned char addr_len; /* hardware addr len */

unsigned long pa_addr; /* protocol address */

unsigned long pa_brdaddr; /* protocol broadcast addr*/

unsigned long pa_dstaddr; /* protocol P-P other addr*/

unsigned long pa_mask; /* protocol netmask */

unsigned short pa_alen; /* protocol address len */

struct dev_mc_list *mc_list; /* M'cast mac addrs */

int mc_count; /* No installed mcasts */

struct ip_mc_list *ip_mc_list; /* IP m'cast filter chain */

__u32 tx_queue_len; /* Max frames per queue */

/* For load balancing driver pair support */

unsigned long pkt_queue; /* Packets queued */

struct device *slave; /* Slave device */

struct net_alias_info *alias_info; /* main dev alias info */

struct net_alias *my_alias; /* alias devs */

/* Pointer to the interface buffers. */

struct sk_buff_head buffs[DEV_NUMBUFFS];

/* Pointers to interface service routines. */

int (*open)(struct device *dev);

int (*stop)(struct device *dev);

int (*hard_start_xmit) (struct sk_buff *skb,

struct device *dev);

int (*hard_header) (struct sk_buff *skb,

struct device *dev,

unsigned short type,

void *daddr,

void *saddr,

unsigned len);

int (*rebuild_header)(void *eth,

struct device *dev,

unsigned long raddr,

struct sk_buff *skb);

void (*set_multicast_list)(struct device *dev);

int (*set_mac_address)(struct device *dev,

void *addr);

int (*do_ioctl)(struct device *dev,

struct ifreq *ifr,

int cmd);

int (*set_config)(struct device *dev,

struct ifmap *map);

void (*header_cache_bind)(struct hh_cache **hhp,

struct device *dev,

unsigned short htype,

__u32 daddr);

void (*header_cache_update)(struct hh_cache *hh,

struct device *dev,

unsigned char * haddr);

int (*change_mtu)(struct device *dev,

int new_mtu);

struct iw_statistics* (*get_wireless_stats)(struct device *dev);

} ;

device_struct

device_struct 数据结构用于登记字符和块设备（存放这个设备的名称和可能进行的文件操作）。 Chrdevs 和 blkdevs 向量表中的每一个有效的成员都分别代表一个字符或块设备。

参见 fs/devices.c

struct device_struct {

const char * name;

struct file_operations * fops;

} ;

file

每一个打开的文件、 socket 等等都用一个 file 数据结构代表

参见 include/linux/fs.h

struct file {

mode_t f_mode;

loff_t f_pos;

unsigned short f_flags;

unsigned short f_count;

unsigned long f_reada, f_ramax, f_raend, f_ralen, f_rawin;

struct file *f_next, *f_prev;

int f_owner; /* pid or -pgrp where SIGIO should be sent */

struct inode * f_inode;

struct file_operations * f_op;

unsigned long f_version;

void *private_data; /* needed for tty driver, and maybe others */

} ;

file_struct

file_struct 数据结构描述了一个进程打开的文件

参见 include/linux/sched.h

struct files_struct {

int count;

fd_set close_on_exec;

fd_set open_fds;

struct file * fd[NR_OPEN];

} ;

fs_struct

参见 include/linux/sched.h

struct fs_struct {

int count;

unsigned short umask;

struct inode * root, * pwd;

} ;

gendisk

gendisk 数据结构存放硬盘的信息。用在初始化过程中找到磁盘，探测分区的时候

参见 include/linux/genhd.h

struct hd_struct {

long start_sect;

long nr_sects;

} ;

struct gendisk {

int major; /* major number of driver */

const char *major_name; /* name of major driver */

int minor_shift; /* number of times minor is shifted to

get real minor */

int max_p; /* maximum partitions per device */

int max_nr; /* maximum number of real devices */

void (*init)(struct gendisk *);

/* Initialization called before we

do our thing */

struct hd_struct *part; /* partition table */

int *sizes; /* device size in blocks, copied to

blk_size[] */

int nr_real; /* number of real devices */

void *real_devices; /* internal use */

struct gendisk *next;

} ;

inode

VFS inode 数据结构存放磁盘上的一个文件或目录的信息

参见 include/linux/fs.h

struct inode {

kdev_t i_dev;

unsigned long i_ino;

umode_t i_mode;

nlink_t i_nlink;

uid_t i_uid;

gid_t i_gid;

kdev_t i_rdev;

off_t i_size;

time_t i_atime;

time_t i_mtime;

time_t i_ctime;

unsigned long i_blksize;

unsigned long i_blocks;

unsigned long i_version;

unsigned long i_nrpages;

struct semaphore i_sem;

struct inode_operations *i_op;

struct super_block *i_sb;

struct wait_queue *i_wait;

struct file_lock *i_flock;

struct vm_area_struct *i_mmap;

struct page *i_pages;

struct dquot *i_dquot[MAXQUOTAS];

struct inode *i_next, *i_prev;

struct inode *i_hash_next, *i_hash_prev;

struct inode *i_bound_to, *i_bound_by;

struct inode *i_mount;

unsigned short i_count;

unsigned short i_flags;

unsigned char i_lock;

unsigned char i_dirt;

unsigned char i_pipe;

unsigned char i_sock;

unsigned char i_seek;

unsigned char i_update;

unsigned short i_writecount;

union {

struct pipe_inode_info pipe_i;

struct minix_inode_info minix_i;

struct ext_inode_info ext_i;

struct ext2_inode_info ext2_i;

struct hpfs_inode_info hpfs_i;

struct msdos_inode_info msdos_i;

struct umsdos_inode_info umsdos_i;

struct iso_inode_info isofs_i;

struct nfs_inode_info nfs_i;

struct xiafs_inode_info xiafs_i;

struct sysv_inode_info sysv_i;

struct affs_inode_info affs_i;

struct ufs_inode_info ufs_i;

struct socket socket_i;

void *generic_ip;

} u;

} ;

　

ipc_perm

ipc_perm 数据结构描述一个系统 V IPC 对象的访问权限

参见 include/linux/ipc.h

　

struct ipc_perm

{

key_t key;

ushort uid; /* owner euid and egid */

ushort gid;

ushort cuid; /* creator euid and egid */

ushort cgid;

ushort mode; /* access modes see mode flags below */

ushort seq; /* sequence number */

} ;

　

irqaction

irqaction 数据结构描述系统的中断处理程序

参见 include/linux/interrupt.h

　

struct irqaction {

void (*handler)(int, void *, struct pt_regs *);

unsigned long flags;

unsigned long mask;

const char *name;

void *dev_id;

struct irqaction *next;

} ;

　

linux_binfmt

Linux 理解的每一个二进制文件格式都用一个 linux_binfmt 数据结构表示

参见 include/linux/binfmt.h

　

struct linux_binfmt {

struct linux_binfmt * next;

long *use_count;

int (*load_binary)(struct linux_binprm *, struct pt_regs * regs);

int (*load_shlib)(int fd);

int (*core_dump)(long signr, struct pt_regs * regs);

} ;

mem_map_t

mem_map_t 数据结构（也叫做 page ）用于存放每一个物理内存页的信息

参见 include/linux/mm.h

typedef struct page {

/* these must be first (free area handling) */

struct page *next;

struct page *prev;

struct inode *inode;

unsigned long offset;

struct page *next_hash;

atomic_t count;

unsigned flags; /* atomic flags, some possibly

updated asynchronously */

unsigned dirty:16,

age:8;

struct wait_queue *wait;

struct page *prev_hash;

struct buffer_head *buffers;

unsigned long swap_unlock_entry;

unsigned long map_nr; /* page->map_nr == page - mem_map */

} mem_map_t;

mm struct

mm_struct 数据结构用于描述一个任务或进程的虚拟内存

参见 include/linux/sched.h

struct mm_struct {

int count;

pgd_t * pgd;

unsigned long context;

unsigned long start_code, end_code, start_data, end_data;

unsigned long start_brk, brk, start_stack, start_mmap;

unsigned long arg_start, arg_end, env_start, env_end;

unsigned long rss, total_vm, locked_vm;

unsigned long def_flags;

struct vm_area_struct * mmap;

struct vm_area_struct * mmap_avl;

struct semaphore mmap_sem;

} ;

pci_bus

系统中的每一个 PCI 总线用一个 pci_bus 数据结构表示

参见 include/linux/pci.h

struct pci_bus {

struct pci_bus *parent; /* parent bus this bridge is on */

struct pci_bus *children; /* chain of P2P bridges on this bus */

struct pci_bus *next; /* chain of all PCI buses */

struct pci_dev *self; /* bridge device as seen by parent */

struct pci_dev *devices; /* devices behind this bridge */

void *sysdata; /* hook for sys-specific extension */

unsigned char number; /* bus number */

unsigned char primary; /* number of primary bridge */

unsigned char secondary; /* number of secondary bridge */

unsigned char subordinate; /* max number of subordinate buses */

} ;

pci_dev

系统中的每一个 PCI 设备，包括 PCI-PCI 和 PCI-ISA 桥设备都用一个 pci_dev 数据结构代表

参见 include/linux/pci.h

/*

* There is one pci_dev structure for each slot-number/function-number

* combination:

*/

struct pci_dev {

struct pci_bus *bus; /* bus this device is on */

struct pci_dev *sibling; /* next device on this bus */

struct pci_dev *next; /* chain of all devices */

void *sysdata; /* hook for sys-specific extension */

unsigned int devfn; /* encoded device & function index */

unsigned short vendor;

unsigned short device;

unsigned int class; /* 3 bytes: (base,sub,prog-if) */

unsigned int master : 1; /* set if device is master capable */

/*

* In theory, the irq level can be read from configuration

* space and all would be fine. However, old PCI chips don't

* support these registers and return 0 instead. For example,

* the Vision864-P rev 0 chip can uses INTA, but returns 0 in

* the interrupt line and pin registers. pci_init()

* initializes this field with the value at PCI_INTERRUPT_LINE

* and it is the job of pcibios_fixup() to change it if

* necessary. The field must not be 0 unless the device

* cannot generate interrupts at all.

*/

unsigned char irq; /* irq generated by this device */

} ;

request

request 用于向系统中的块设备发出请求。请求都是从 / 向 buffer cache 读 / 写数据块

参见 include/linux/blkdev.h

struct request {

volatile int rq_status;

#define RQ_INACTIVE (-1)

#define RQ_ACTIVE 1

#define RQ_SCSI_BUSY 0xffff

#define RQ_SCSI_DONE 0xfffe

#define RQ_SCSI_DISCONNECTING 0xffe0

kdev_t rq_dev;

int cmd; /* READ or WRITE */

int errors;

unsigned long sector;

unsigned long nr_sectors;

unsigned long current_nr_sectors;

char * buffer;

struct semaphore * sem;

struct buffer_head * bh;

struct buffer_head * bhtail;

struct request * next;

} ;

rtable

每一个 rtable 数据结构都存放向一个 IP 主机发送报文的路由的信息。 Rtable 数据结构在 IP route 缓存中使用。

参见 include/net/route.h

struct rtable

{

struct rtable *rt_next;

__u32 rt_dst;

__u32 rt_src;

__u32 rt_gateway;

atomic_t rt_refcnt;

atomic_t rt_use;

unsigned long rt_window;

atomic_t rt_lastuse;

struct hh_cache *rt_hh;

struct device *rt_dev;

unsigned short rt_flags;

unsigned short rt_mtu;

unsigned short rt_irtt;

unsigned char rt_tos;

} ;

semaphore

信号灯用于保护重要数据结构和代码区域。

参见 include/asm/semaphore.h

struct semaphore {

int count;

int waking;

int lock ; /* to make waking testing atomic */

struct wait_queue *wait;

} ;

sk_buff

sk_buff 数据结构当网络数据在协议层之间移动的过程中描述网络数据。

参见 include/linux/sk_buff.h

struct sk_buff

{

struct sk_buff *next; /* Next buffer in list */

struct sk_buff *prev; /* Previous buffer in list */

struct sk_buff_head *list; /* List we are on */

int magic_debug_cookie;

struct sk_buff *link3; /* Link for IP protocol level buffer chains */

struct sock *sk; /* Socket we are owned by */

unsigned long when; /* used to compute rtt's */

struct timeval stamp; /* Time we arrived */

struct device *dev; /* Device we arrived on/are leaving by */

union

{

struct tcphdr *th;

struct ethhdr *eth;

struct iphdr *iph;

struct udphdr *uh;

unsigned char *raw;

/* for passing file handles in a unix domain socket */

void *filp;

} h;

union

{

/* As yet incomplete physical layer views */

unsigned char *raw;

struct ethhdr *ethernet;

} mac;

struct iphdr *ip_hdr; /* For IPPROTO_RAW */

unsigned long len; /* Length of actual data */

unsigned long csum; /* Checksum */

__u32 saddr; /* IP source address */

__u32 daddr; /* IP target address */

__u32 raddr; /* IP next hop address */

__u32 seq; /* TCP sequence number */

__u32 end_seq; /* seq [+ fin] [+ syn] + datalen */

__u32 ack_seq; /* TCP ack sequence number */

unsigned char proto_priv[16];

volatile char acked, /* Are we acked ? */

used, /* Are we in use ? */

free, /* How to free this buffer */

arp; /* Has IP/ARP resolution finished */

unsigned char tries, /* Times tried */

lock, /* Are we locked ? */

localroute, /* Local routing asserted for this frame */

pkt_type, /* Packet class */

pkt_bridged, /* Tracker for bridging */

ip_summed; /* Driver fed us an IP checksum */

#define PACKET_HOST 0 /* To us */

#define PACKET_BROADCAST 1 /* To all */

#define PACKET_MULTICAST 2 /* To group */

#define PACKET_OTHERHOST 3 /* To someone else */

unsigned short users; /* User count - see datagram.c,tcp.c */

unsigned short protocol; /* Packet protocol from driver. */

unsigned int truesize; /* Buffer size */

atomic_t count; /* reference count */

struct sk_buff *data_skb; /* Link to the actual data skb */

unsigned char *head; /* Head of buffer */

unsigned char *data; /* Data head pointer */

unsigned char *tail; /* Tail pointer */

unsigned char *end; /* End pointer */

void (*destructor)(struct sk_buff *); /* Destruct function */

__u16 redirport; /* Redirect port */

} ;

sock

每一个 sock 数据结构都存放一个 BSD socket 中和协议相关的信息。例如，对于一个 INET socket ，这个数据结构会存放所有的 TCP/IP 和 UDP/IP 相关的信息

参见 include/linux/net.h

struct sock

{

/* This must be first. */

struct sock *sklist_next;

struct sock *sklist_prev;

struct options *opt;

atomic_t wmem_alloc;

atomic_t rmem_alloc;

unsigned long allocation; /* Allocation mode */

__u32 write_seq;

__u32 sent_seq;

__u32 acked_seq;

__u32 copied_seq;

__u32 rcv_ack_seq;

unsigned short rcv_ack_cnt; /* count of same ack */

__u32 window_seq;

__u32 fin_seq;

__u32 urg_seq;

__u32 urg_data;

__u32 syn_seq;

int users; /* user count */

/*

* Not all are volatile, but some are, so we

* might as well say they all are.

*/

volatile char dead,

urginline,

intr,

blog,

done,

reuse,

keepopen,

linger,

delay_acks,

destroy,

ack_timed,

no_check,

zapped,

broadcast,

nonagle,

bsdism;

unsigned long lingertime;

int proc;

struct sock *next;

struct sock **pprev;

struct sock *bind_next;

struct sock **bind_pprev;

struct sock *pair;

int hashent;

struct sock *prev;

struct sk_buff *volatile send_head;

struct sk_buff *volatile send_next;

struct sk_buff *volatile send_tail;

struct sk_buff_head back_log;

struct sk_buff *partial;

struct timer_list partial_timer;

long retransmits;

struct sk_buff_head write_queue,

receive_queue;

struct proto *prot;

struct wait_queue **sleep;

__u32 daddr;

__u32 saddr; /* Sending source */

__u32 rcv_saddr; /* Bound address */

unsigned short max_unacked;

unsigned short window;

__u32 lastwin_seq; /* sequence number when we last

updated the window we offer */

__u32 high_seq; /* sequence number when we did

current fast retransmit */

volatile unsigned long ato; /* ack timeout */

volatile unsigned long lrcvtime; /* jiffies at last data rcv */

volatile unsigned long idletime; /* jiffies at last rcv */

unsigned int bytes_rcv;

/*

* mss is min(mtu, max_window)

*/

unsigned short mtu; /* mss negotiated in the syn's */

volatile unsigned short mss; /* current eff. mss - can change */

volatile unsigned short user_mss; /* mss requested by user in ioctl */

volatile unsigned short max_window;

unsigned long window_clamp;

unsigned int ssthresh;

unsigned short num;

volatile unsigned short cong_window;

volatile unsigned short cong_count;

volatile unsigned short packets_out;

volatile unsigned short shutdown;

volatile unsigned long rtt;

volatile unsigned long mdev;

volatile unsigned long rto;

volatile unsigned short backoff;

int err, err_soft; /* Soft holds errors that don't

cause failure but are the cause

of a persistent failure not

just 'timed out' */

unsigned char protocol;

volatile unsigned char state;

unsigned char ack_backlog;

unsigned char max_ack_backlog;

unsigned char priority;

unsigned char debug;

int rcvbuf;

int sndbuf;

unsigned short type;

unsigned char localroute; /* Route locally only */

/*

* This is where all the private (optional) areas that don't

* overlap will eventually live.

*/

union

{

struct unix_opt af_unix;

#if defined(CONFIG_ATALK) || defined(CONFIG_ATALK_MODULE)

struct atalk_sock af_at;

#endif

#if defined(CONFIG_IPX) || defined(CONFIG_IPX_MODULE)

struct ipx_opt af_ipx;

#endif

#ifdef CONFIG_INET

struct inet_packet_opt af_packet;

#ifdef CONFIG_NUTCP

struct tcp_opt af_tcp;

#endif

#endif

} protinfo;

/*

* IP 'private area'

*/

int ip_ttl; /* TTL setting */

int ip_tos; /* TOS */

struct tcphdr dummy_th;

struct timer_list keepalive_timer; /* TCP keepalive hack */

struct timer_list retransmit_timer; /* TCP retransmit timer */

struct timer_list delack_timer; /* TCP delayed ack timer */

int ip_xmit_timeout; /* Why the timeout is running */

struct rtable *ip_route_cache; /* Cached output route */

unsigned char ip_hdrincl; /* Include headers ? */

#ifdef CONFIG_IP_MULTICAST

int ip_mc_ttl; /* Multicasting TTL */

int ip_mc_loop; /* Loopback */

char ip_mc_name[MAX_ADDR_LEN]; /* Multicast device name */

struct ip_mc_socklist *ip_mc_list; /* Group array */

#endif

/*

* This part is used for the timeout functions (timer.c).

*/

int timeout; /* What are we waiting for? */

struct timer_list timer; /* This is the TIME_WAIT/receive

* timer when we are doing IP

*/

struct timeval stamp;

/*

* Identd

*/

struct socket *socket;

/*

* Callbacks

*/

void (*state_change)(struct sock *sk);

void (*data_ready)(struct sock *sk,int bytes);

void (*write_space)(struct sock *sk);

void (*error_report)(struct sock *sk);

} ;

socket

每一个 socket 数据结构都存放一个 BSD socket 的信息。它不会独立存在，实际上是 VFS inode 数据结构的一部分

参见 include/linux/net.h

struct socket {

short type; /* SOCK_STREAM, ... */

socket_state state;

long flags;

struct proto_ops *ops; /* protocols do most everything */

void *data; /* protocol data */

struct socket *conn; /* server socket connected to */

struct socket *iconn; /* incomplete client conn.s */

struct socket *next;

struct wait_queue **wait; /* ptr to place to wait on */

struct inode *inode;

struct fasync_struct *fasync_list; /* Asynchronous wake up list */

struct file *file; /* File back pointer for gc */

} ;

task_struct

每一个 task_struct 描述系统中的一个任务或进程

参见 include/linux/sched.h

struct task_struct {

/* these are hardcoded - don't touch */

volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */

long counter;

long priority;

unsigned long signal;

unsigned long blocked; /* bitmap of masked signals */

unsigned long flags; /* per process flags, defined below */

int errno;

long debugreg[8]; /* Hardware debugging registers */

struct exec_domain *exec_domain;

/* various fields */

struct linux_binfmt *binfmt;

struct task_struct *next_task, *prev_task;

struct task_struct *next_run, *prev_run;

unsigned long saved_kernel_stack;

unsigned long kernel_stack_page;

int exit_code, exit_signal;

/* ??? */

unsigned long personality;

int dumpable:1;

int did_exec:1;

int pid;

int pgrp;

int tty_old_pgrp;

int session;

/* boolean value for session group leader */

int leader;

int groups[NGROUPS];

/*

* pointers to (original) parent process, youngest child, younger sibling,

* older sibling, respectively. (p->father can be replaced with

* p->p_pptr->pid)

*/

struct task_struct *p_opptr, *p_pptr, *p_cptr,

*p_ysptr, *p_osptr;

struct wait_queue *wait_chldexit;

unsigned short uid,euid,suid,fsuid;

unsigned short gid,egid,sgid,fsgid;

unsigned long timeout, policy, rt_priority;

unsigned long it_real_value, it_prof_value, it_virt_value;

unsigned long it_real_incr, it_prof_incr, it_virt_incr;

struct timer_list real_timer;

long utime, stime, cutime, cstime, start_time;

/* mm fault and swap info: this can arguably be seen as either

mm-specific or thread-specific */

unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap;

int swappable:1;

unsigned long swap_address;

unsigned long old_maj_flt; /* old value of maj_flt */

unsigned long dec_flt; /* page fault count of the last time */

unsigned long swap_cnt; /* number of pages to swap on next pass */

/* limits */

struct rlimit rlim[RLIM_NLIMITS];

unsigned short used_math;

char comm[16];

/* file system info */

int link_count;

struct tty_struct *tty; /* NULL if no tty */

/* ipc stuff */

struct sem_undo *semundo;

struct sem_queue *semsleeping;

/* ldt for this task - used by Wine. If NULL, default_ldt is used */

struct desc_struct *ldt;

/* tss for this task */

struct thread_struct tss;

/* filesystem information */

struct fs_struct *fs;

/* open file information */

struct files_struct *files;

/* memory management info */

struct mm_struct *mm;

/* signal handlers */

struct signal_struct *sig;

#ifdef __SMP__

int processor;

int last_processor;

int lock_depth; /* Lock depth.

We can context switch in and out

of holding a syscall kernel lock... */

#endif

} ;

timer_list

timer_list 数据结构用于实现进程的实时计时器。

参见 include/linux/timer.h

struct timer_list {

struct timer_list *next;

struct timer_list *prev;

unsigned long expires;

unsigned long data;

void (*function)(unsigned long);

} ;

tq_struct

每一个任务队列（ tq_struct ）数据结构都存放正在排队的工作的信息。通常是一个设备驱动程序需要的任务，但是不需要立即完成。

参见 include/linux/tqueue.h

struct tq_struct {

struct tq_struct *next; /* linked list of active bh's */

int sync; /* must be initialized to zero */

void (*routine)(void *); /* function to call */

void *data; /* argument to function */

} ;

vm_area_struct

　

每一个 vm_area_struct 数据结构描述一个进程的一个虚拟内存区

参见 include/linux/mm.h

struct vm_area_struct {

struct mm_struct * vm_mm; /* VM area parameters */

unsigned long vm_start;

unsigned long vm_end;

pgprot_t vm_page_prot;

unsigned short vm_flags;

/* AVL tree of VM areas per task, sorted by address */

short vm_avl_height;

struct vm_area_struct * vm_avl_left;

struct vm_area_struct * vm_avl_right;

/* linked list of VM areas per task, sorted by address */

struct vm_area_struct * vm_next;

/* for areas with inode, the circular list inode->i_mmap */

/* for shm areas, the circular list of attaches */

/* otherwise unused */

struct vm_area_struct * vm_next_share;

struct vm_area_struct * vm_prev_share;

/* more */

struct vm_operations_struct * vm_ops;

unsigned long vm_offset;

struct inode * vm_inode;

unsigned long vm_pte; /* shared mem */

} ;