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。
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);
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。
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
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
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 */
list.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
需要自备gcc标准手册，posix手册