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Linux 核心--16.Linux数据结构

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第十五章 Linux核心数据结构 

本章列出了Linux实用的主要数据结构。 


block_dev_struct
此结构用于向核心登记块设备,它还被buffer cache实用。所有此类结构都位于blk_dev数组中。 

struct blk_dev_struct {
    void (*request_fn)(void);
    struct request * current_request;
    struct request   plug;
    struct tq_struct plug_tq;
};

buffer_head
此结构包含关于buffer cache中一块缓存的信息。 

/* 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
系统中每个网络设备都用一个设备数据结构来表示。 

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
此结构被块设备和字符设备用来向核心登记(包含设备名称以及可对此设备进行的文件操作)。chrdevs和blkdevs 中的每个有效分别表示一个字符设备和块设备。 

struct device_struct {
    const char * name;
    struct file_operations * fops;
};

file
每个打开的文件、套接口都用此结构表示。 

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 */
};

files_struct
描叙被某进程打开的所有文件。 

struct files_struct {
  int count;
  fd_set close_on_exec;
  fd_set open_fds;
  struct file * fd[NR_OPEN];
};

fs_struct

struct fs_struct {
  int count;
  unsigned short umask;
  struct inode * root, * pwd;
};

gendisk
包含关于某个硬盘的信息。用于磁盘初始化与分区检查时。 

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
此VFS inode结构描叙磁盘上一个文件或目录的信息。 

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
此结构描叙对一个系统V IPC对象的存取权限。 

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
用来描叙系统的中断处理过程。 

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
用来表示可被Linux理解的二进制文件格式。 

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
用来保存每个物理页面的信息。 

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
用来描叙某任务或进程的虚拟内存。 

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
表示系统中的一个PCI总线。 

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
表示系统中的每个PCI设备,包括PCI-PCI和PCI-PCI桥接器。 

/*
 * 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
被用来向系统的块设备发送请求。它总是向buffer cache读出或写入数据块。 

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
用来描叙向某个IP主机发送包的路由信息。此结构在IP路由cache内部实用。 

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
保护临界区数据结构和代码信号灯。 

struct semaphore {
    int count;
    int waking;
    int lock ;                /* to make waking testing atomic */
    struct wait_queue *wait;
};

sk_buff
用来描叙在协议层之间交换的网络数据。 

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
包含BSD套接口的协议相关信息。例如对于一个INET(Internet Address Domain)套接口此数据结构 包含TCP/IP和UDP/IP信息。 

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
包含BSD套接口的信息。它不独立存在,一般位于一个VFS inode结构中。 

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
用来描叙系统中的进程或任务。 

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
用来为进程实现实时时钟。 

struct timer_list {
  struct timer_list *next;
  struct timer_list *prev;
  unsigned long expires;
  unsigned long data;
  void (*function)(unsigned long);
};

tq_struct
每个任务队列结构(tq_struct)包含着已经排队的任务信息。它被设备驱动用来描叙那些无需立刻 执行的任务。 

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
表示某进程的一个虚拟内存区域。 

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 */
};

标签: linux