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分类: LINUX

2006-03-20 11:08:11

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     
		
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