Linux内核学习--写一个c程序，并在内核中编译，运行

 1 #include <linux/module.h>
 2 #include <linux/init.h>
 3 #include <linux/kernel.h>
 4 
 5 //模块许可
 6 MODULE_LICENSE("Dual BSD/GPL");
 7 
 8 //模块加载
 9 static int hello_init(void)
10 {
11     printk(KERN_ALERT "Hi I am here\n");
12     return 0;       
13 }
14 
15 //模块卸载
16 static void hello_exit(void)
17 {
18     printk(KERN_ALERT "Goodbye\n");
19 }
20 
21 //注册
22 module_init(hello_init);
23 module_exit(hello_init);

 1 obj-m +=hello.o
 2 
 3 #generate the path
 4 CURRENT_PATH:= $(shell pwd)
 5 
 6 #the current kernel version number
 7 LINUX_KERNEL:=$(shell uname -r)
 8 
 9 #the absolute path
10 LINUX_KERNEL_PATH:=usr/src/linux-headers-$(LINUX_KERNEL)
11 
12 #compile object
13 all:
14         make -C $(LINUX_KERNEL_PATH) M=(CURRENT_PATH) modules
15 
16 #clean content under current path
17 clean:
18         make -c $(LINUX_KERNEL_PATH) m=(CURRENT_PATH) clean

  1 #ifndef _LINUX_TYPES_H
  2 #define _LINUX_TYPES_H
  3 
  4 #include <asm/types.h>
  5 
  6 #ifndef __ASSEMBLY__
  7 #ifdef    __KERNEL__
  8 
  9 #define DECLARE_BITMAP(name,bits)  10     unsigned long name[BITS_TO_LONGS(bits)]
 11 
 12 #endif
 13 
 14 #include <linux/posix_types.h>
 15 
 16 #ifdef __KERNEL__
 17 
 18 typedef __u32 __kernel_dev_t;
 19 
 20 typedef __kernel_fd_set        fd_set;
 21 typedef __kernel_dev_t        dev_t;
 22 typedef __kernel_ino_t        ino_t;
 23 typedef __kernel_mode_t        mode_t;
 24 typedef __kernel_nlink_t    nlink_t;
 25 typedef __kernel_off_t        off_t;
 26 typedef __kernel_pid_t        pid_t;
 27 typedef __kernel_daddr_t    daddr_t;
 28 typedef __kernel_key_t        key_t;
 29 typedef __kernel_suseconds_t    suseconds_t;
 30 typedef __kernel_timer_t    timer_t;
 31 typedef __kernel_clockid_t    clockid_t;
 32 typedef __kernel_mqd_t        mqd_t;
 33 
 34 typedef _Bool            bool;
 35 
 36 typedef __kernel_uid32_t    uid_t;
 37 typedef __kernel_gid32_t    gid_t;
 38 typedef __kernel_uid16_t        uid16_t;
 39 typedef __kernel_gid16_t        gid16_t;
 40 
 41 typedef unsigned long        uintptr_t;
 42 
 43 #ifdef CONFIG_UID16
 44 /* This is defined by include/asm-{arch}/posix_types.h */
 45 typedef __kernel_old_uid_t    old_uid_t;
 46 typedef __kernel_old_gid_t    old_gid_t;
 47 #endif /* CONFIG_UID16 */
 48 
 49 #if defined(__GNUC__)
 50 typedef __kernel_loff_t        loff_t;
 51 #endif
 52 
 53 /*
 54  * The following typedefs are also protected by individual ifdefs for
 55  * historical reasons:
 56  */
 57 #ifndef _SIZE_T
 58 #define _SIZE_T
 59 typedef __kernel_size_t        size_t;
 60 #endif
 61 
 62 #ifndef _SSIZE_T
 63 #define _SSIZE_T
 64 typedef __kernel_ssize_t    ssize_t;
 65 #endif
 66 
 67 #ifndef _PTRDIFF_T
 68 #define _PTRDIFF_T
 69 typedef __kernel_ptrdiff_t    ptrdiff_t;
 70 #endif
 71 
 72 #ifndef _TIME_T
 73 #define _TIME_T
 74 typedef __kernel_time_t        time_t;
 75 #endif
 76 
 77 #ifndef _CLOCK_T
 78 #define _CLOCK_T
 79 typedef __kernel_clock_t    clock_t;
 80 #endif
 81 
 82 #ifndef _CADDR_T
 83 #define _CADDR_T
 84 typedef __kernel_caddr_t    caddr_t;
 85 #endif
 86 
 87 /* bsd */
 88 typedef unsigned char        u_char;
 89 typedef unsigned short        u_short;
 90 typedef unsigned int        u_int;
 91 typedef unsigned long        u_long;
 92 
 93 /* sysv */
 94 typedef unsigned char        unchar;
 95 typedef unsigned short        ushort;
 96 typedef unsigned int        uint;
 97 typedef unsigned long        ulong;
 98 
 99 #ifndef __BIT_TYPES_DEFINED__
100 #define __BIT_TYPES_DEFINED__
101 
102 typedef        __u8        u_int8_t;
103 typedef        __s8        int8_t;
104 typedef        __u16        u_int16_t;
105 typedef        __s16        int16_t;
106 typedef        __u32        u_int32_t;
107 typedef        __s32        int32_t;
108 
109 #endif /* !(__BIT_TYPES_DEFINED__) */
110 
111 typedef        __u8        uint8_t;
112 typedef        __u16        uint16_t;
113 typedef        __u32        uint32_t;
114 
115 #if defined(__GNUC__)
116 typedef        __u64        uint64_t;
117 typedef        __u64        u_int64_t;
118 typedef        __s64        int64_t;
119 #endif
120 
121 /* this is a special 64bit data type that is 8-byte aligned */
122 #define aligned_u64 __u64 __attribute__((aligned(8)))
123 #define aligned_be64 __be64 __attribute__((aligned(8)))
124 #define aligned_le64 __le64 __attribute__((aligned(8)))
125 
126 /**
127  * The type used for indexing onto a disc or disc partition.
128  *
129  * Linux always considers sectors to be 512 bytes long independently
130  * of the devices real block size.
131  *
132  * blkcnt_t is the type of the inode‘s block count.
133  */
134 #ifdef CONFIG_LBDAF
135 typedef u64 sector_t;
136 typedef u64 blkcnt_t;
137 #else
138 typedef unsigned long sector_t;
139 typedef unsigned long blkcnt_t;
140 #endif
141 
142 /*
143  * The type of an index into the pagecache.  Use a #define so asm/types.h
144  * can override it.
145  */
146 #ifndef pgoff_t
147 #define pgoff_t unsigned long
148 #endif
149 
150 #endif /* __KERNEL__ */
151 
152 /*
153  * Below are truly Linux-specific types that should never collide with
154  * any application/library that wants linux/types.h.
155  */
156 
157 #ifdef __CHECKER__
158 #define __bitwise__ __attribute__((bitwise))
159 #else
160 #define __bitwise__
161 #endif
162 #ifdef __CHECK_ENDIAN__
163 #define __bitwise __bitwise__
164 #else
165 #define __bitwise
166 #endif
167 
168 typedef __u16 __bitwise __le16;
169 typedef __u16 __bitwise __be16;
170 typedef __u32 __bitwise __le32;
171 typedef __u32 __bitwise __be32;
172 typedef __u64 __bitwise __le64;
173 typedef __u64 __bitwise __be64;
174 
175 typedef __u16 __bitwise __sum16;
176 typedef __u32 __bitwise __wsum;
177 
178 #ifdef __KERNEL__
179 typedef unsigned __bitwise__ gfp_t;
180 typedef unsigned __bitwise__ fmode_t;
181 
182 #ifdef CONFIG_PHYS_ADDR_T_64BIT
183 typedef u64 phys_addr_t;
184 #else
185 typedef u32 phys_addr_t;
186 #endif
187 
188 typedef phys_addr_t resource_size_t;
189 
190 typedef struct {
191     volatile int counter;
192 } atomic_t;
193 
194 #ifdef CONFIG_64BIT
195 typedef struct {
196     volatile long counter;
197 } atomic64_t;
198 #endif
199 
200 struct ustat {
201     __kernel_daddr_t    f_tfree;
202     __kernel_ino_t        f_tinode;
203     char            f_fname[6];
204     char            f_fpack[6];
205 };
206 
207 #endif    /* __KERNEL__ */
208 #endif /*  __ASSEMBLY__ */
209 #endif /* _LINUX_TYPES_H */

  1 #ifndef _LINUX_LIST_H
  2 #define _LINUX_LIST_H
  3 
  4 #include <linux/stddef.h>
  5 #include <linux/poison.h>
  6 #include <linux/prefetch.h>
  7 #include <asm/system.h>
  8 
  9 /*
 10  * Simple doubly linked list implementation.
 11  *
 12  * Some of the internal functions ("__xxx") are useful when
 13  * manipulating whole lists rather than single entries, as
 14  * sometimes we already know the next/prev entries and we can
 15  * generate better code by using them directly rather than
 16  * using the generic single-entry routines.
 17  */
 18 
 19 struct list_head {
 20     struct list_head *next, *prev;
 21 };
 22 
 23 #define LIST_HEAD_INIT(name) { &(name), &(name) }
 24 
 25 #define LIST_HEAD(name)  26     struct list_head name = LIST_HEAD_INIT(name)
 27 
 28 static inline void INIT_LIST_HEAD(struct list_head *list)
 29 {
 30     list->next = list;
 31     list->prev = list;
 32 }
 33 
 34 /*
 35  * Insert a new entry between two known consecutive entries.
 36  *
 37  * This is only for internal list manipulation where we know
 38  * the prev/next entries already!
 39  */
 40 #ifndef CONFIG_DEBUG_LIST
 41 static inline void __list_add(struct list_head *new,
 42                   struct list_head *prev,
 43                   struct list_head *next)
 44 {
 45     next->prev = new;
 46     new->next = next;
 47     new->prev = prev;
 48     prev->next = new;
 49 }
 50 #else
 51 extern void __list_add(struct list_head *new,
 52                   struct list_head *prev,
 53                   struct list_head *next);
 54 #endif
 55 
 56 /**
 57  * list_add - add a new entry
 58  * @new: new entry to be added
 59  * @head: list head to add it after
 60  *
 61  * Insert a new entry after the specified head.
 62  * This is good for implementing stacks.
 63  */
 64 static inline void list_add(struct list_head *new, struct list_head *head)
 65 {
 66     __list_add(new, head, head->next);
 67 }
 68 
 69 
 70 /**
 71  * list_add_tail - add a new entry
 72  * @new: new entry to be added
 73  * @head: list head to add it before
 74  *
 75  * Insert a new entry before the specified head.
 76  * This is useful for implementing queues.
 77  */
 78 static inline void list_add_tail(struct list_head *new, struct list_head *head)
 79 {
 80     __list_add(new, head->prev, head);
 81 }
 82 
 83 /*
 84  * Delete a list entry by making the prev/next entries
 85  * point to each other.
 86  *
 87  * This is only for internal list manipulation where we know
 88  * the prev/next entries already!
 89  */
 90 static inline void __list_del(struct list_head * prev, struct list_head * next)
 91 {
 92     next->prev = prev;
 93     prev->next = next;
 94 }
 95 
 96 /**
 97  * list_del - deletes entry from list.
 98  * @entry: the element to delete from the list.
 99  * Note: list_empty() on entry does not return true after this, the entry is
100  * in an undefined state.
101  */
102 #ifndef CONFIG_DEBUG_LIST
103 static inline void list_del(struct list_head *entry)
104 {
105     __list_del(entry->prev, entry->next);
106     entry->next = LIST_POISON1;
107     entry->prev = LIST_POISON2;
108 }
109 #else
110 extern void list_del(struct list_head *entry);
111 #endif
112 
113 /**
114  * list_replace - replace old entry by new one
115  * @old : the element to be replaced
116  * @new : the new element to insert
117  *
118  * If @old was empty, it will be overwritten.
119  */
120 static inline void list_replace(struct list_head *old,
121                 struct list_head *new)
122 {
123     new->next = old->next;
124     new->next->prev = new;
125     new->prev = old->prev;
126     new->prev->next = new;
127 }
128 
129 static inline void list_replace_init(struct list_head *old,
130                     struct list_head *new)
131 {
132     list_replace(old, new);
133     INIT_LIST_HEAD(old);
134 }
135 
136 /**
137  * list_del_init - deletes entry from list and reinitialize it.
138  * @entry: the element to delete from the list.
139  */
140 static inline void list_del_init(struct list_head *entry)
141 {
142     __list_del(entry->prev, entry->next);
143     INIT_LIST_HEAD(entry);
144 }
145 
146 /**
147  * list_move - delete from one list and add as another‘s head
148  * @list: the entry to move
149  * @head: the head that will precede our entry
150  */
151 static inline void list_move(struct list_head *list, struct list_head *head)
152 {
153     __list_del(list->prev, list->next);
154     list_add(list, head);
155 }
156 
157 /**
158  * list_move_tail - delete from one list and add as another‘s tail
159  * @list: the entry to move
160  * @head: the head that will follow our entry
161  */
162 static inline void list_move_tail(struct list_head *list,
163                   struct list_head *head)
164 {
165     __list_del(list->prev, list->next);
166     list_add_tail(list, head);
167 }
168 
169 /**
170  * list_is_last - tests whether @list is the last entry in list @head
171  * @list: the entry to test
172  * @head: the head of the list
173  */
174 static inline int list_is_last(const struct list_head *list,
175                 const struct list_head *head)
176 {
177     return list->next == head;
178 }
179 
180 /**
181  * list_empty - tests whether a list is empty
182  * @head: the list to test.
183  */
184 static inline int list_empty(const struct list_head *head)
185 {
186     return head->next == head;
187 }
188 
189 /**
190  * list_empty_careful - tests whether a list is empty and not being modified
191  * @head: the list to test
192  *
193  * Description:
194  * tests whether a list is empty _and_ checks that no other CPU might be
195  * in the process of modifying either member (next or prev)
196  *
197  * NOTE: using list_empty_careful() without synchronization
198  * can only be safe if the only activity that can happen
199  * to the list entry is list_del_init(). Eg. it cannot be used
200  * if another CPU could re-list_add() it.
201  */
202 static inline int list_empty_careful(const struct list_head *head)
203 {
204     struct list_head *next = head->next;
205     return (next == head) && (next == head->prev);
206 }
207 
208 /**
209  * list_is_singular - tests whether a list has just one entry.
210  * @head: the list to test.
211  */
212 static inline int list_is_singular(const struct list_head *head)
213 {
214     return !list_empty(head) && (head->next == head->prev);
215 }
216 
217 static inline void __list_cut_position(struct list_head *list,
218         struct list_head *head, struct list_head *entry)
219 {
220     struct list_head *new_first = entry->next;
221     list->next = head->next;
222     list->next->prev = list;
223     list->prev = entry;
224     entry->next = list;
225     head->next = new_first;
226     new_first->prev = head;
227 }
228 
229 /**
230  * list_cut_position - cut a list into two
231  * @list: a new list to add all removed entries
232  * @head: a list with entries
233  * @entry: an entry within head, could be the head itself
234  *    and if so we won‘t cut the list
235  *
236  * This helper moves the initial part of @head, up to and
237  * including @entry, from @head to @list. You should
238  * pass on @entry an element you know is on @head. @list
239  * should be an empty list or a list you do not care about
240  * losing its data.
241  *
242  */
243 static inline void list_cut_position(struct list_head *list,
244         struct list_head *head, struct list_head *entry)
245 {
246     if (list_empty(head))
247         return;
248     if (list_is_singular(head) &&
249         (head->next != entry && head != entry))
250         return;
251     if (entry == head)
252         INIT_LIST_HEAD(list);
253     else
254         __list_cut_position(list, head, entry);
255 }
256 
257 static inline void __list_splice(const struct list_head *list,
258                  struct list_head *prev,
259                  struct list_head *next)
260 {
261     struct list_head *first = list->next;
262     struct list_head *last = list->prev;
263 
264     first->prev = prev;
265     prev->next = first;
266 
267     last->next = next;
268     next->prev = last;
269 }
270 
271 /**
272  * list_splice - join two lists, this is designed for stacks
273  * @list: the new list to add.
274  * @head: the place to add it in the first list.
275  */
276 static inline void list_splice(const struct list_head *list,
277                 struct list_head *head)
278 {
279     if (!list_empty(list))
280         __list_splice(list, head, head->next);
281 }
282 
283 /**
284  * list_splice_tail - join two lists, each list being a queue
285  * @list: the new list to add.
286  * @head: the place to add it in the first list.
287  */
288 static inline void list_splice_tail(struct list_head *list,
289                 struct list_head *head)
290 {
291     if (!list_empty(list))
292         __list_splice(list, head->prev, head);
293 }
294 
295 /**
296  * list_splice_init - join two lists and reinitialise the emptied list.
297  * @list: the new list to add.
298  * @head: the place to add it in the first list.
299  *
300  * The list at @list is reinitialised
301  */
302 static inline void list_splice_init(struct list_head *list,
303                     struct list_head *head)
304 {
305     if (!list_empty(list)) {
306         __list_splice(list, head, head->next);
307         INIT_LIST_HEAD(list);
308     }
309 }
310 
311 /**
312  * list_splice_tail_init - join two lists and reinitialise the emptied list
313  * @list: the new list to add.
314  * @head: the place to add it in the first list.
315  *
316  * Each of the lists is a queue.
317  * The list at @list is reinitialised
318  */
319 static inline void list_splice_tail_init(struct list_head *list,
320                      struct list_head *head)
321 {
322     if (!list_empty(list)) {
323         __list_splice(list, head->prev, head);
324         INIT_LIST_HEAD(list);
325     }
326 }
327 
328 /**
329  * list_entry - get the struct for this entry
330  * @ptr:    the &struct list_head pointer.
331  * @type:    the type of the struct this is embedded in.
332  * @member:    the name of the list_struct within the struct.
333  */
334 #define list_entry(ptr, type, member) 335     container_of(ptr, type, member)
336 
337 /**
338  * list_first_entry - get the first element from a list
339  * @ptr:    the list head to take the element from.
340  * @type:    the type of the struct this is embedded in.
341  * @member:    the name of the list_struct within the struct.
342  *
343  * Note, that list is expected to be not empty.
344  */
345 #define list_first_entry(ptr, type, member) 346     list_entry((ptr)->next, type, member)
347 
348 /**
349  * list_for_each    -    iterate over a list
350  * @pos:    the &struct list_head to use as a loop cursor.
351  * @head:    the head for your list.
352  */
353 #define list_for_each(pos, head) 354     for (pos = (head)->next; prefetch(pos->next), pos != (head); 355             pos = pos->next)
356 
357 /**
358  * __list_for_each    -    iterate over a list
359  * @pos:    the &struct list_head to use as a loop cursor.
360  * @head:    the head for your list.
361  *
362  * This variant differs from list_for_each() in that it‘s the
363  * simplest possible list iteration code, no prefetching is done.
364  * Use this for code that knows the list to be very short (empty
365  * or 1 entry) most of the time.
366  */
367 #define __list_for_each(pos, head) 368     for (pos = (head)->next; pos != (head); pos = pos->next)
369 
370 /**
371  * list_for_each_prev    -    iterate over a list backwards
372  * @pos:    the &struct list_head to use as a loop cursor.
373  * @head:    the head for your list.
374  */
375 #define list_for_each_prev(pos, head) 376     for (pos = (head)->prev; prefetch(pos->prev), pos != (head); 377             pos = pos->prev)
378 
379 /**
380  * list_for_each_safe - iterate over a list safe against removal of list entry
381  * @pos:    the &struct list_head to use as a loop cursor.
382  * @n:        another &struct list_head to use as temporary storage
383  * @head:    the head for your list.
384  */
385 #define list_for_each_safe(pos, n, head) 386     for (pos = (head)->next, n = pos->next; pos != (head); 387         pos = n, n = pos->next)
388 
389 /**
390  * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
391  * @pos:    the &struct list_head to use as a loop cursor.
392  * @n:        another &struct list_head to use as temporary storage
393  * @head:    the head for your list.
394  */
395 #define list_for_each_prev_safe(pos, n, head) 396     for (pos = (head)->prev, n = pos->prev; 397          prefetch(pos->prev), pos != (head); 398          pos = n, n = pos->prev)
399 
400 /**
401  * list_for_each_entry    -    iterate over list of given type
402  * @pos:    the type * to use as a loop cursor.
403  * @head:    the head for your list.
404  * @member:    the name of the list_struct within the struct.
405  */
406 #define list_for_each_entry(pos, head, member)                407     for (pos = list_entry((head)->next, typeof(*pos), member);    408          prefetch(pos->member.next), &pos->member != (head);     409          pos = list_entry(pos->member.next, typeof(*pos), member))
410 
411 /**
412  * list_for_each_entry_reverse - iterate backwards over list of given type.
413  * @pos:    the type * to use as a loop cursor.
414  * @head:    the head for your list.
415  * @member:    the name of the list_struct within the struct.
416  */
417 #define list_for_each_entry_reverse(pos, head, member)            418     for (pos = list_entry((head)->prev, typeof(*pos), member);    419          prefetch(pos->member.prev), &pos->member != (head);     420          pos = list_entry(pos->member.prev, typeof(*pos), member))
421 
422 /**
423  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
424  * @pos:    the type * to use as a start point
425  * @head:    the head of the list
426  * @member:    the name of the list_struct within the struct.
427  *
428  * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
429  */
430 #define list_prepare_entry(pos, head, member) 431     ((pos) ? : list_entry(head, typeof(*pos), member))
432 
433 /**
434  * list_for_each_entry_continue - continue iteration over list of given type
435  * @pos:    the type * to use as a loop cursor.
436  * @head:    the head for your list.
437  * @member:    the name of the list_struct within the struct.
438  *
439  * Continue to iterate over list of given type, continuing after
440  * the current position.
441  */
442 #define list_for_each_entry_continue(pos, head, member)         443     for (pos = list_entry(pos->member.next, typeof(*pos), member);    444          prefetch(pos->member.next), &pos->member != (head);    445          pos = list_entry(pos->member.next, typeof(*pos), member))
446 
447 /**
448  * list_for_each_entry_continue_reverse - iterate backwards from the given point
449  * @pos:    the type * to use as a loop cursor.
450  * @head:    the head for your list.
451  * @member:    the name of the list_struct within the struct.
452  *
453  * Start to iterate over list of given type backwards, continuing after
454  * the current position.
455  */
456 #define list_for_each_entry_continue_reverse(pos, head, member)        457     for (pos = list_entry(pos->member.prev, typeof(*pos), member);    458          prefetch(pos->member.prev), &pos->member != (head);    459          pos = list_entry(pos->member.prev, typeof(*pos), member))
460 
461 /**
462  * list_for_each_entry_from - iterate over list of given type from the current point
463  * @pos:    the type * to use as a loop cursor.
464  * @head:    the head for your list.
465  * @member:    the name of the list_struct within the struct.
466  *
467  * Iterate over list of given type, continuing from current position.
468  */
469 #define list_for_each_entry_from(pos, head, member)             470     for (; prefetch(pos->member.next), &pos->member != (head);    471          pos = list_entry(pos->member.next, typeof(*pos), member))
472 
473 /**
474  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
475  * @pos:    the type * to use as a loop cursor.
476  * @n:        another type * to use as temporary storage
477  * @head:    the head for your list.
478  * @member:    the name of the list_struct within the struct.
479  */
480 #define list_for_each_entry_safe(pos, n, head, member)            481     for (pos = list_entry((head)->next, typeof(*pos), member),    482         n = list_entry(pos->member.next, typeof(*pos), member);    483          &pos->member != (head);                     484          pos = n, n = list_entry(n->member.next, typeof(*n), member))
485 
486 /**
487  * list_for_each_entry_safe_continue
488  * @pos:    the type * to use as a loop cursor.
489  * @n:        another type * to use as temporary storage
490  * @head:    the head for your list.
491  * @member:    the name of the list_struct within the struct.
492  *
493  * Iterate over list of given type, continuing after current point,
494  * safe against removal of list entry.
495  */
496 #define list_for_each_entry_safe_continue(pos, n, head, member)         497     for (pos = list_entry(pos->member.next, typeof(*pos), member),         498         n = list_entry(pos->member.next, typeof(*pos), member);        499          &pos->member != (head);                        500          pos = n, n = list_entry(n->member.next, typeof(*n), member))
501 
502 /**
503  * list_for_each_entry_safe_from
504  * @pos:    the type * to use as a loop cursor.
505  * @n:        another type * to use as temporary storage
506  * @head:    the head for your list.
507  * @member:    the name of the list_struct within the struct.
508  *
509  * Iterate over list of given type from current point, safe against
510  * removal of list entry.
511  */
512 #define list_for_each_entry_safe_from(pos, n, head, member)             513     for (n = list_entry(pos->member.next, typeof(*pos), member);        514          &pos->member != (head);                        515          pos = n, n = list_entry(n->member.next, typeof(*n), member))
516 
517 /**
518  * list_for_each_entry_safe_reverse
519  * @pos:    the type * to use as a loop cursor.
520  * @n:        another type * to use as temporary storage
521  * @head:    the head for your list.
522  * @member:    the name of the list_struct within the struct.
523  *
524  * Iterate backwards over list of given type, safe against removal
525  * of list entry.
526  */
527 #define list_for_each_entry_safe_reverse(pos, n, head, member)        528     for (pos = list_entry((head)->prev, typeof(*pos), member),    529         n = list_entry(pos->member.prev, typeof(*pos), member);    530          &pos->member != (head);                     531          pos = n, n = list_entry(n->member.prev, typeof(*n), member))
532 
533 /*
534  * Double linked lists with a single pointer list head.
535  * Mostly useful for hash tables where the two pointer list head is
536  * too wasteful.
537  * You lose the ability to access the tail in O(1).
538  */
539 
540 struct hlist_head {
541     struct hlist_node *first;
542 };
543 
544 struct hlist_node {
545     struct hlist_node *next, **pprev;
546 };
547 
548 #define HLIST_HEAD_INIT { .first = NULL }
549 #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
550 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
551 static inline void INIT_HLIST_NODE(struct hlist_node *h)
552 {
553     h->next = NULL;
554     h->pprev = NULL;
555 }
556 
557 static inline int hlist_unhashed(const struct hlist_node *h)
558 {
559     return !h->pprev;
560 }
561 
562 static inline int hlist_empty(const struct hlist_head *h)
563 {
564     return !h->first;
565 }
566 
567 static inline void __hlist_del(struct hlist_node *n)
568 {
569     struct hlist_node *next = n->next;
570     struct hlist_node **pprev = n->pprev;
571     *pprev = next;
572     if (next)
573         next->pprev = pprev;
574 }
575 
576 static inline void hlist_del(struct hlist_node *n)
577 {
578     __hlist_del(n);
579     n->next = LIST_POISON1;
580     n->pprev = LIST_POISON2;
581 }
582 
583 static inline void hlist_del_init(struct hlist_node *n)
584 {
585     if (!hlist_unhashed(n)) {
586         __hlist_del(n);
587         INIT_HLIST_NODE(n);
588     }
589 }
590 
591 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
592 {
593     struct hlist_node *first = h->first;
594     n->next = first;
595     if (first)
596         first->pprev = &n->next;
597     h->first = n;
598     n->pprev = &h->first;
599 }
600 
601 /* next must be != NULL */
602 static inline void hlist_add_before(struct hlist_node *n,
603                     struct hlist_node *next)
604 {
605     n->pprev = next->pprev;
606     n->next = next;
607     next->pprev = &n->next;
608     *(n->pprev) = n;
609 }
610 
611 static inline void hlist_add_after(struct hlist_node *n,
612                     struct hlist_node *next)
613 {
614     next->next = n->next;
615     n->next = next;
616     next->pprev = &n->next;
617 
618     if(next->next)
619         next->next->pprev  = &next->next;
620 }
621 
622 /*
623  * Move a list from one list head to another. Fixup the pprev
624  * reference of the first entry if it exists.
625  */
626 static inline void hlist_move_list(struct hlist_head *old,
627                    struct hlist_head *new)
628 {
629     new->first = old->first;
630     if (new->first)
631         new->first->pprev = &new->first;
632     old->first = NULL;
633 }
634 
635 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
636 
637 #define hlist_for_each(pos, head) 638     for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); 639          pos = pos->next)
640 
641 #define hlist_for_each_safe(pos, n, head) 642     for (pos = (head)->first; pos && ({ n = pos->next; 1; }); 643          pos = n)
644 
645 /**
646  * hlist_for_each_entry    - iterate over list of given type
647  * @tpos:    the type * to use as a loop cursor.
648  * @pos:    the &struct hlist_node to use as a loop cursor.
649  * @head:    the head for your list.
650  * @member:    the name of the hlist_node within the struct.
651  */
652 #define hlist_for_each_entry(tpos, pos, head, member)             653     for (pos = (head)->first;                     654          pos && ({ prefetch(pos->next); 1;}) &&             655         ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); 656          pos = pos->next)
657 
658 /**
659  * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
660  * @tpos:    the type * to use as a loop cursor.
661  * @pos:    the &struct hlist_node to use as a loop cursor.
662  * @member:    the name of the hlist_node within the struct.
663  */
664 #define hlist_for_each_entry_continue(tpos, pos, member)         665     for (pos = (pos)->next;                         666          pos && ({ prefetch(pos->next); 1;}) &&             667         ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); 668          pos = pos->next)
669 
670 /**
671  * hlist_for_each_entry_from - iterate over a hlist continuing from current point
672  * @tpos:    the type * to use as a loop cursor.
673  * @pos:    the &struct hlist_node to use as a loop cursor.
674  * @member:    the name of the hlist_node within the struct.
675  */
676 #define hlist_for_each_entry_from(tpos, pos, member)             677     for (; pos && ({ prefetch(pos->next); 1;}) &&             678         ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); 679          pos = pos->next)
680 
681 /**
682  * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
683  * @tpos:    the type * to use as a loop cursor.
684  * @pos:    the &struct hlist_node to use as a loop cursor.
685  * @n:        another &struct hlist_node to use as temporary storage
686  * @head:    the head for your list.
687  * @member:    the name of the hlist_node within the struct.
688  */
689 #define hlist_for_each_entry_safe(tpos, pos, n, head, member)          690     for (pos = (head)->first;                     691          pos && ({ n = pos->next; 1; }) &&                  692         ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); 693          pos = n)
694 
695 #endif