Linux内核学习--写一个c程序，并在内核中编译，运行

20140506

今天开始学习伟大的开源代表作：Linux内核。之前的工作流于几个简单命令的应用，因着对Android操作系统的情愫，“忍不住”跟随陈利君老师的步伐，开启OS内核之旅。学习路径之一是直接从代码入手，下面来写一个hello.c内核模块。

说明：

这个路径/usr/src/linux-headers-2.6.32-22/include/linux是引用的头文件。

内核模块固定格式：module_init()/ module_exit(),module函数是从头文件中来的。

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>

 //模块许可
 MODULE_LICENSE("Dual BSD/GPL");

 //模块加载
 static int hello_init(void)
 {
     printk(KERN_ALERT "Hi I am here\n");
     return ;
 }

 //模块卸载
 static void hello_exit(void)
 {
     printk(KERN_ALERT "Goodbye\n");
 }

 //注册
 module_init(hello_init);
 module_exit(hello_init);

我们知道，linux对于c语言写的程序，使用glibc库函数，并gcc编译-连接-运行；内核中使用make编译，insmod插入模块到内核中，rmmod卸载模块。make命令默认寻找Makefile文件，本质上也是gcc调用。下面创建Makefile文件。

 obj-m +=hello.o

 #generate the path
 CURRENT_PATH:= $(shell pwd)

 #the current kernel version number
 LINUX_KERNEL:=$(shell uname -r)

 #the absolute path
 LINUX_KERNEL_PATH:=usr/src/linux-headers-$(LINUX_KERNEL)

 #compile object
 all:
         make -C $(LINUX_KERNEL_PATH) M=(CURRENT_PATH) modules

 #clean content under current path
 clean:
         make -c $(LINUX_KERNEL_PATH) m=(CURRENT_PATH) clean

执行make -> 完成后当前路径出现hello.ko文件 -> insmod hello.ko ->内核结果默认输出到log中，使用dmesg查看，果然有 -> lsmod 命令，发现hello已经成为运行在内核中的一个模块啦 ->rmmod hello 卸载模块 -> dmesg,发现卸载工作留下了log信息->lsmod 找不到hello模块，说明卸载完毕。

接下来学习types.h和list.h两个头文件

types.h

 #ifndef _LINUX_TYPES_H
 #define _LINUX_TYPES_H

 #include <asm/types.h>

 #ifndef __ASSEMBLY__
 #ifdef    __KERNEL__

 #define DECLARE_BITMAP(name,bits) \
     unsigned long name[BITS_TO_LONGS(bits)]

 #endif

 #include <linux/posix_types.h>

 #ifdef __KERNEL__

 typedef __u32 __kernel_dev_t;

 typedef __kernel_fd_set        fd_set;
 typedef __kernel_dev_t        dev_t;
 typedef __kernel_ino_t        ino_t;
 typedef __kernel_mode_t        mode_t;
 typedef __kernel_nlink_t    nlink_t;
 typedef __kernel_off_t        off_t;
 typedef __kernel_pid_t        pid_t;
 typedef __kernel_daddr_t    daddr_t;
 typedef __kernel_key_t        key_t;
 typedef __kernel_suseconds_t    suseconds_t;
 typedef __kernel_timer_t    timer_t;
 typedef __kernel_clockid_t    clockid_t;
 typedef __kernel_mqd_t        mqd_t;

 typedef _Bool            bool;

 typedef __kernel_uid32_t    uid_t;
 typedef __kernel_gid32_t    gid_t;
 typedef __kernel_uid16_t        uid16_t;
 typedef __kernel_gid16_t        gid16_t;

 typedef unsigned long        uintptr_t;

 #ifdef CONFIG_UID16
 /* This is defined by include/asm-{arch}/posix_types.h */
 typedef __kernel_old_uid_t    old_uid_t;
 typedef __kernel_old_gid_t    old_gid_t;
 #endif /* CONFIG_UID16 */

 #if defined(__GNUC__)
 typedef __kernel_loff_t        loff_t;
 #endif

 /*
  * The following typedefs are also protected by individual ifdefs for
  * historical reasons:
  */
 #ifndef _SIZE_T
 #define _SIZE_T
 typedef __kernel_size_t        size_t;
 #endif

 #ifndef _SSIZE_T
 #define _SSIZE_T
 typedef __kernel_ssize_t    ssize_t;
 #endif

 #ifndef _PTRDIFF_T
 #define _PTRDIFF_T
 typedef __kernel_ptrdiff_t    ptrdiff_t;
 #endif

 #ifndef _TIME_T
 #define _TIME_T
 typedef __kernel_time_t        time_t;
 #endif

 #ifndef _CLOCK_T
 #define _CLOCK_T
 typedef __kernel_clock_t    clock_t;
 #endif

 #ifndef _CADDR_T
 #define _CADDR_T
 typedef __kernel_caddr_t    caddr_t;
 #endif

 /* bsd */
 typedef unsigned char        u_char;
 typedef unsigned short        u_short;
 typedef unsigned int        u_int;
 typedef unsigned long        u_long;

 /* sysv */
 typedef unsigned char        unchar;
 typedef unsigned short        ushort;
 typedef unsigned int        uint;
 typedef unsigned long        ulong;

 #ifndef __BIT_TYPES_DEFINED__
 #define __BIT_TYPES_DEFINED__

 typedef        __u8        u_int8_t;
 typedef        __s8        int8_t;
 typedef        __u16        u_int16_t;
 typedef        __s16        int16_t;
 typedef        __u32        u_int32_t;
 typedef        __s32        int32_t;

 #endif /* !(__BIT_TYPES_DEFINED__) */

 typedef        __u8        uint8_t;
 typedef        __u16        uint16_t;
 typedef        __u32        uint32_t;

 #if defined(__GNUC__)
 typedef        __u64        uint64_t;
 typedef        __u64        u_int64_t;
 typedef        __s64        int64_t;
 #endif

 /* this is a special 64bit data type that is 8-byte aligned */
 #define aligned_u64 __u64 __attribute__((aligned(8)))
 #define aligned_be64 __be64 __attribute__((aligned(8)))
 #define aligned_le64 __le64 __attribute__((aligned(8)))

 /**
  * The type used for indexing onto a disc or disc partition.
  *
  * Linux always considers sectors to be 512 bytes long independently
  * of the devices real block size.
  *
  * blkcnt_t is the type of the inode's block count.
  */
 #ifdef CONFIG_LBDAF
 typedef u64 sector_t;
 typedef u64 blkcnt_t;
 #else
 typedef unsigned long sector_t;
 typedef unsigned long blkcnt_t;
 #endif

 /*
  * The type of an index into the pagecache.  Use a #define so asm/types.h
  * can override it.
  */
 #ifndef pgoff_t
 #define pgoff_t unsigned long
 #endif

 #endif /* __KERNEL__ */

 /*
  * Below are truly Linux-specific types that should never collide with
  * any application/library that wants linux/types.h.
  */

 #ifdef __CHECKER__
 #define __bitwise__ __attribute__((bitwise))
 #else
 #define __bitwise__
 #endif
 #ifdef __CHECK_ENDIAN__
 #define __bitwise __bitwise__
 #else
 #define __bitwise
 #endif

 typedef __u16 __bitwise __le16;
 typedef __u16 __bitwise __be16;
 typedef __u32 __bitwise __le32;
 typedef __u32 __bitwise __be32;
 typedef __u64 __bitwise __le64;
 typedef __u64 __bitwise __be64;

 typedef __u16 __bitwise __sum16;
 typedef __u32 __bitwise __wsum;

 #ifdef __KERNEL__
 typedef unsigned __bitwise__ gfp_t;
 typedef unsigned __bitwise__ fmode_t;

 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 typedef u64 phys_addr_t;
 #else
 typedef u32 phys_addr_t;
 #endif

 typedef phys_addr_t resource_size_t;

 typedef struct {
     volatile int counter;
 } atomic_t;

 #ifdef CONFIG_64BIT
 typedef struct {
     volatile long counter;
 } atomic64_t;
 #endif

 struct ustat {
     __kernel_daddr_t    f_tfree;
     __kernel_ino_t        f_tinode;
     char            f_fname[];
     char            f_fpack[];
 };

 #endif    /* __KERNEL__ */
 #endif /*  __ASSEMBLY__ */
 #endif /* _LINUX_TYPES_H */

list.h

 #ifndef _LINUX_LIST_H
 #define _LINUX_LIST_H

 #include <linux/stddef.h>
 #include <linux/poison.h>
 #include <linux/prefetch.h>
 #include <asm/system.h>

 /*
  * Simple doubly linked list implementation.
  *
  * Some of the internal functions ("__xxx") are useful when
  * manipulating whole lists rather than single entries, as
  * sometimes we already know the next/prev entries and we can
  * generate better code by using them directly rather than
  * using the generic single-entry routines.
  */

 struct list_head {
     struct list_head *next, *prev;
 };

 #define LIST_HEAD_INIT(name) { &(name), &(name) }

 #define LIST_HEAD(name) \
     struct list_head name = LIST_HEAD_INIT(name)

 static inline void INIT_LIST_HEAD(struct list_head *list)
 {
     list->next = list;
     list->prev = list;
 }

 /*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
 #ifndef CONFIG_DEBUG_LIST
 static inline void __list_add(struct list_head *new,
                   struct list_head *prev,
                   struct list_head *next)
 {
     next->prev = new;
     new->next = next;
     new->prev = prev;
     prev->next = new;
 }
 #else
 extern void __list_add(struct list_head *new,
                   struct list_head *prev,
                   struct list_head *next);
 #endif

 /**
  * list_add - add a new entry
  * @new: new entry to be added
  * @head: list head to add it after
  *
  * Insert a new entry after the specified head.
  * This is good for implementing stacks.
  */
 static inline void list_add(struct list_head *new, struct list_head *head)
 {
     __list_add(new, head, head->next);
 }

 /**
  * list_add_tail - add a new entry
  * @new: new entry to be added
  * @head: list head to add it before
  *
  * Insert a new entry before the specified head.
  * This is useful for implementing queues.
  */
 static inline void list_add_tail(struct list_head *new, struct list_head *head)
 {
     __list_add(new, head->prev, head);
 }

 /*
  * Delete a list entry by making the prev/next entries
  * point to each other.
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
 static inline void __list_del(struct list_head * prev, struct list_head * next)
 {
     next->prev = prev;
     prev->next = next;
 }

 /**
  * list_del - deletes entry from list.
  * @entry: the element to delete from the list.
  * Note: list_empty() on entry does not return true after this, the entry is
  * in an undefined state.
  */
 #ifndef CONFIG_DEBUG_LIST
 static inline void list_del(struct list_head *entry)
 {
     __list_del(entry->prev, entry->next);
     entry->next = LIST_POISON1;
     entry->prev = LIST_POISON2;
 }
 #else
 extern void list_del(struct list_head *entry);
 #endif

 /**
  * list_replace - replace old entry by new one
  * @old : the element to be replaced
  * @new : the new element to insert
  *
  * If @old was empty, it will be overwritten.
  */
 static inline void list_replace(struct list_head *old,
                 struct list_head *new)
 {
     new->next = old->next;
     new->next->prev = new;
     new->prev = old->prev;
     new->prev->next = new;
 }

 static inline void list_replace_init(struct list_head *old,
                     struct list_head *new)
 {
     list_replace(old, new);
     INIT_LIST_HEAD(old);
 }

 /**
  * list_del_init - deletes entry from list and reinitialize it.
  * @entry: the element to delete from the list.
  */
 static inline void list_del_init(struct list_head *entry)
 {
     __list_del(entry->prev, entry->next);
     INIT_LIST_HEAD(entry);
 }

 /**
  * list_move - delete from one list and add as another's head
  * @list: the entry to move
  * @head: the head that will precede our entry
  */
 static inline void list_move(struct list_head *list, struct list_head *head)
 {
     __list_del(list->prev, list->next);
     list_add(list, head);
 }

 /**
  * list_move_tail - delete from one list and add as another's tail
  * @list: the entry to move
  * @head: the head that will follow our entry
  */
 static inline void list_move_tail(struct list_head *list,
                   struct list_head *head)
 {
     __list_del(list->prev, list->next);
     list_add_tail(list, head);
 }

 /**
  * list_is_last - tests whether @list is the last entry in list @head
  * @list: the entry to test
  * @head: the head of the list
  */
 static inline int list_is_last(const struct list_head *list,
                 const struct list_head *head)
 {
     return list->next == head;
 }

 /**
  * list_empty - tests whether a list is empty
  * @head: the list to test.
  */
 static inline int list_empty(const struct list_head *head)
 {
     return head->next == head;
 }

 /**
  * list_empty_careful - tests whether a list is empty and not being modified
  * @head: the list to test
  *
  * Description:
  * tests whether a list is empty _and_ checks that no other CPU might be
  * in the process of modifying either member (next or prev)
  *
  * NOTE: using list_empty_careful() without synchronization
  * can only be safe if the only activity that can happen
  * to the list entry is list_del_init(). Eg. it cannot be used
  * if another CPU could re-list_add() it.
  */
 static inline int list_empty_careful(const struct list_head *head)
 {
     struct list_head *next = head->next;
     return (next == head) && (next == head->prev);
 }

 /**
  * list_is_singular - tests whether a list has just one entry.
  * @head: the list to test.
  */
 static inline int list_is_singular(const struct list_head *head)
 {
     return !list_empty(head) && (head->next == head->prev);
 }

 static inline void __list_cut_position(struct list_head *list,
         struct list_head *head, struct list_head *entry)
 {
     struct list_head *new_first = entry->next;
     list->next = head->next;
     list->next->prev = list;
     list->prev = entry;
     entry->next = list;
     head->next = new_first;
     new_first->prev = head;
 }

 /**
  * list_cut_position - cut a list into two
  * @list: a new list to add all removed entries
  * @head: a list with entries
  * @entry: an entry within head, could be the head itself
  *    and if so we won't cut the list
  *
  * This helper moves the initial part of @head, up to and
  * including @entry, from @head to @list. You should
  * pass on @entry an element you know is on @head. @list
  * should be an empty list or a list you do not care about
  * losing its data.
  *
  */
 static inline void list_cut_position(struct list_head *list,
         struct list_head *head, struct list_head *entry)
 {
     if (list_empty(head))
         return;
     if (list_is_singular(head) &&
         (head->next != entry && head != entry))
         return;
     if (entry == head)
         INIT_LIST_HEAD(list);
     else
         __list_cut_position(list, head, entry);
 }

 static inline void __list_splice(const struct list_head *list,
                  struct list_head *prev,
                  struct list_head *next)
 {
     struct list_head *first = list->next;
     struct list_head *last = list->prev;

     first->prev = prev;
     prev->next = first;

     last->next = next;
     next->prev = last;
 }

 /**
  * list_splice - join two lists, this is designed for stacks
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  */
 static inline void list_splice(const struct list_head *list,
                 struct list_head *head)
 {
     if (!list_empty(list))
         __list_splice(list, head, head->next);
 }

 /**
  * list_splice_tail - join two lists, each list being a queue
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  */
 static inline void list_splice_tail(struct list_head *list,
                 struct list_head *head)
 {
     if (!list_empty(list))
         __list_splice(list, head->prev, head);
 }

 /**
  * list_splice_init - join two lists and reinitialise the emptied list.
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  *
  * The list at @list is reinitialised
  */
 static inline void list_splice_init(struct list_head *list,
                     struct list_head *head)
 {
     if (!list_empty(list)) {
         __list_splice(list, head, head->next);
         INIT_LIST_HEAD(list);
     }
 }

 /**
  * list_splice_tail_init - join two lists and reinitialise the emptied list
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  *
  * Each of the lists is a queue.
  * The list at @list is reinitialised
  */
 static inline void list_splice_tail_init(struct list_head *list,
                      struct list_head *head)
 {
     if (!list_empty(list)) {
         __list_splice(list, head->prev, head);
         INIT_LIST_HEAD(list);
     }
 }

 /**
  * list_entry - get the struct for this entry
  * @ptr:    the &struct list_head pointer.
  * @type:    the type of the struct this is embedded in.
  * @member:    the name of the list_struct within the struct.
  */
 #define list_entry(ptr, type, member) \
     container_of(ptr, type, member)

 /**
  * list_first_entry - get the first element from a list
  * @ptr:    the list head to take the element from.
  * @type:    the type of the struct this is embedded in.
  * @member:    the name of the list_struct within the struct.
  *
  * Note, that list is expected to be not empty.
  */
 #define list_first_entry(ptr, type, member) \
     list_entry((ptr)->next, type, member)

 /**
  * list_for_each    -    iterate over a list
  * @pos:    the &struct list_head to use as a loop cursor.
  * @head:    the head for your list.
  */
 #define list_for_each(pos, head) \
     for (pos = (head)->next; prefetch(pos->next), pos != (head); \
             pos = pos->next)

 /**
  * __list_for_each    -    iterate over a list
  * @pos:    the &struct list_head to use as a loop cursor.
  * @head:    the head for your list.
  *
  * This variant differs from list_for_each() in that it's the
  * simplest possible list iteration code, no prefetching is done.
  * Use this for code that knows the list to be very short (empty
  * or 1 entry) most of the time.
  */
 #define __list_for_each(pos, head) \
     for (pos = (head)->next; pos != (head); pos = pos->next)

 /**
  * list_for_each_prev    -    iterate over a list backwards
  * @pos:    the &struct list_head to use as a loop cursor.
  * @head:    the head for your list.
  */
 #define list_for_each_prev(pos, head) \
     for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
             pos = pos->prev)

 /**
  * list_for_each_safe - iterate over a list safe against removal of list entry
  * @pos:    the &struct list_head to use as a loop cursor.
  * @n:        another &struct list_head to use as temporary storage
  * @head:    the head for your list.
  */
 #define list_for_each_safe(pos, n, head) \
     for (pos = (head)->next, n = pos->next; pos != (head); \
         pos = n, n = pos->next)

 /**
  * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
  * @pos:    the &struct list_head to use as a loop cursor.
  * @n:        another &struct list_head to use as temporary storage
  * @head:    the head for your list.
  */
 #define list_for_each_prev_safe(pos, n, head) \
     for (pos = (head)->prev, n = pos->prev; \
          prefetch(pos->prev), pos != (head); \
          pos = n, n = pos->prev)

 /**
  * list_for_each_entry    -    iterate over list of given type
  * @pos:    the type * to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  */
 #define list_for_each_entry(pos, head, member)                \
     for (pos = list_entry((head)->next, typeof(*pos), member);    \
          prefetch(pos->member.next), &pos->member != (head);     \
          pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_reverse - iterate backwards over list of given type.
  * @pos:    the type * to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  */
 #define list_for_each_entry_reverse(pos, head, member)            \
     for (pos = list_entry((head)->prev, typeof(*pos), member);    \
          prefetch(pos->member.prev), &pos->member != (head);     \
          pos = list_entry(pos->member.prev, typeof(*pos), member))

 /**
  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
  * @pos:    the type * to use as a start point
  * @head:    the head of the list
  * @member:    the name of the list_struct within the struct.
  *
  * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
  */
 #define list_prepare_entry(pos, head, member) \
     ((pos) ? : list_entry(head, typeof(*pos), member))

 /**
  * list_for_each_entry_continue - continue iteration over list of given type
  * @pos:    the type * to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Continue to iterate over list of given type, continuing after
  * the current position.
  */
 #define list_for_each_entry_continue(pos, head, member)         \
     for (pos = list_entry(pos->member.next, typeof(*pos), member);    \
          prefetch(pos->member.next), &pos->member != (head);    \
          pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_continue_reverse - iterate backwards from the given point
  * @pos:    the type * to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Start to iterate over list of given type backwards, continuing after
  * the current position.
  */
 #define list_for_each_entry_continue_reverse(pos, head, member)        \
     for (pos = list_entry(pos->member.prev, typeof(*pos), member);    \
          prefetch(pos->member.prev), &pos->member != (head);    \
          pos = list_entry(pos->member.prev, typeof(*pos), member))

 /**
  * list_for_each_entry_from - iterate over list of given type from the current point
  * @pos:    the type * to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Iterate over list of given type, continuing from current position.
  */
 #define list_for_each_entry_from(pos, head, member)             \
     for (; prefetch(pos->member.next), &pos->member != (head);    \
          pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
  * @pos:    the type * to use as a loop cursor.
  * @n:        another type * to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  */
 #define list_for_each_entry_safe(pos, n, head, member)            \
     for (pos = list_entry((head)->next, typeof(*pos), member),    \
         n = list_entry(pos->member.next, typeof(*pos), member);    \
          &pos->member != (head);                     \
          pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_continue
  * @pos:    the type * to use as a loop cursor.
  * @n:        another type * to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Iterate over list of given type, continuing after current point,
  * safe against removal of list entry.
  */
 #define list_for_each_entry_safe_continue(pos, n, head, member)         \
     for (pos = list_entry(pos->member.next, typeof(*pos), member),         \
         n = list_entry(pos->member.next, typeof(*pos), member);        \
          &pos->member != (head);                        \
          pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_from
  * @pos:    the type * to use as a loop cursor.
  * @n:        another type * to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Iterate over list of given type from current point, safe against
  * removal of list entry.
  */
 #define list_for_each_entry_safe_from(pos, n, head, member)             \
     for (n = list_entry(pos->member.next, typeof(*pos), member);        \
          &pos->member != (head);                        \
          pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_reverse
  * @pos:    the type * to use as a loop cursor.
  * @n:        another type * to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  *
  * Iterate backwards over list of given type, safe against removal
  * of list entry.
  */
 #define list_for_each_entry_safe_reverse(pos, n, head, member)        \
     for (pos = list_entry((head)->prev, typeof(*pos), member),    \
         n = list_entry(pos->member.prev, typeof(*pos), member);    \
          &pos->member != (head);                     \
          pos = n, n = list_entry(n->member.prev, typeof(*n), member))

 /*
  * Double linked lists with a single pointer list head.
  * Mostly useful for hash tables where the two pointer list head is
  * too wasteful.
  * You lose the ability to access the tail in O(1).
  */

 struct hlist_head {
     struct hlist_node *first;
 };

 struct hlist_node {
     struct hlist_node *next, **pprev;
 };

 #define HLIST_HEAD_INIT { .first = NULL }
 #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
 static inline void INIT_HLIST_NODE(struct hlist_node *h)
 {
     h->next = NULL;
     h->pprev = NULL;
 }

 static inline int hlist_unhashed(const struct hlist_node *h)
 {
     return !h->pprev;
 }

 static inline int hlist_empty(const struct hlist_head *h)
 {
     return !h->first;
 }

 static inline void __hlist_del(struct hlist_node *n)
 {
     struct hlist_node *next = n->next;
     struct hlist_node **pprev = n->pprev;
     *pprev = next;
     if (next)
         next->pprev = pprev;
 }

 static inline void hlist_del(struct hlist_node *n)
 {
     __hlist_del(n);
     n->next = LIST_POISON1;
     n->pprev = LIST_POISON2;
 }

 static inline void hlist_del_init(struct hlist_node *n)
 {
     if (!hlist_unhashed(n)) {
         __hlist_del(n);
         INIT_HLIST_NODE(n);
     }
 }

 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
 {
     struct hlist_node *first = h->first;
     n->next = first;
     if (first)
         first->pprev = &n->next;
     h->first = n;
     n->pprev = &h->first;
 }

 /* next must be != NULL */
 static inline void hlist_add_before(struct hlist_node *n,
                     struct hlist_node *next)
 {
     n->pprev = next->pprev;
     n->next = next;
     next->pprev = &n->next;
     *(n->pprev) = n;
 }

 static inline void hlist_add_after(struct hlist_node *n,
                     struct hlist_node *next)
 {
     next->next = n->next;
     n->next = next;
     next->pprev = &n->next;

     if(next->next)
         next->next->pprev  = &next->next;
 }

 /*
  * Move a list from one list head to another. Fixup the pprev
  * reference of the first entry if it exists.
  */
 static inline void hlist_move_list(struct hlist_head *old,
                    struct hlist_head *new)
 {
     new->first = old->first;
     if (new->first)
         new->first->pprev = &new->first;
     old->first = NULL;
 }

 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)

 #define hlist_for_each(pos, head) \
     for (pos = (head)->first; pos && ({ prefetch(pos->next); ; }); \
          pos = pos->next)

 #define hlist_for_each_safe(pos, n, head) \
     for (pos = (head)->first; pos && ({ n = pos->next; ; }); \
          pos = n)

 /**
  * hlist_for_each_entry    - iterate over list of given type
  * @tpos:    the type * to use as a loop cursor.
  * @pos:    the &struct hlist_node to use as a loop cursor.
  * @head:    the head for your list.
  * @member:    the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry(tpos, pos, head, member)             \
     for (pos = (head)->first;                     \
          pos && ({ prefetch(pos->next); ;}) &&             \
         ({ tpos = hlist_entry(pos, typeof(*tpos), member); ;}); \
          pos = pos->next)

 /**
  * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
  * @tpos:    the type * to use as a loop cursor.
  * @pos:    the &struct hlist_node to use as a loop cursor.
  * @member:    the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_continue(tpos, pos, member)         \
     for (pos = (pos)->next;                         \
          pos && ({ prefetch(pos->next); ;}) &&             \
         ({ tpos = hlist_entry(pos, typeof(*tpos), member); ;}); \
          pos = pos->next)

 /**
  * hlist_for_each_entry_from - iterate over a hlist continuing from current point
  * @tpos:    the type * to use as a loop cursor.
  * @pos:    the &struct hlist_node to use as a loop cursor.
  * @member:    the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_from(tpos, pos, member)             \
     for (; pos && ({ prefetch(pos->next); ;}) &&             \
         ({ tpos = hlist_entry(pos, typeof(*tpos), member); ;}); \
          pos = pos->next)

 /**
  * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
  * @tpos:    the type * to use as a loop cursor.
  * @pos:    the &struct hlist_node to use as a loop cursor.
  * @n:        another &struct hlist_node to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the hlist_node within the struct.
  */
 #define hlist_for_each_entry_safe(tpos, pos, n, head, member)          \
     for (pos = (head)->first;                     \
          pos && ({ n = pos->next; ; }) &&                  \
         ({ tpos = hlist_entry(pos, typeof(*tpos), member); ;}); \
          pos = n)

 #endif

需要自备gcc标准手册，posix手册