Error: Implicit declaration function 'init _ mutex '[-werror = implicit-function-Declaration]

In the new Linux kernel, init_mutex has been abolished, and the new version uses the sema_init function. I checked the definitions of earlier versions:

Platform: x86 32-bit

Kernel: 2.6.30

Definition:

Linux/include/Linux/semaphore. H 1/* 2 * copyright (c) 2008 Intel Corporation 3 * Author: Matthew Wilcox <willy@linux.intel.com> 4*5 * distributed under the terms of the gnu gpl, version 2 6*7 * Please see kernel/semaphore. c For documentation of these functions 8 */9 # ifndef _ linux_semaphore_h 10 # DEFINE _ linux_semaphore_h 11 12 # include <Linux/list. h> 13 # include <Linux/spinlock. h> 14 15/* Please don't access any members of this structure directly */16 struct semaphore {17 spinlock_t lock; 18 unsigned int count; 19 struct list_head wait_list; 20 }; 21 22 # DEFINE _ semaphore_initializer (name, n) \ 23 {\ 24. lock = _ spin_lock_unlocked (name ). lock), \ 25. count = N, \ 26. wait_list = list_head_init (name ). wait_list), \ 27} 28 29 # define declare_mutex (name) \ 30 struct semaphore name = _ semaphore_initializer (name, 1) 31 32 static inline void sema_init (struct semaphore * SEM, int Val) 33 {34 static struct lock_class_key _ key; 35 * SEM = (struct semaphore) _ semaphore_initializer (* SEM, Val); 36 lockdep_init_map (& SEM-> lock. dep_map, "semaphore-> lock", & __ key, 0); 37} 38 39 # define init_mutex (SEM) sema_init (SEM, 1) // In the latest version, none of the two macros define 40 # define init_mutex_locked (SEM) sema_init (SEM, 0) 41 42 extern void down (struct semaphore * SEM ); 43 extern int _ must_check down_interruptible (struct semaphore * SEM); 44 extern int _ must_check down_killable (struct semaphore * SEM ); 45 extern int _ must_check down_trylock (struct semaphore * SEM); 46 extern int _ must_check down_timeout (struct semaphore * SEM, long jiffies ); 47 extern void up (struct semaphore * SEM); 48 49 # endif/* _ linux_semaphore_h */50

Note: The init_mutex () function initializes the semaphores as mutex. Mutex is a special case of semaphores. It can prevent data from being read and written by two different systems.

Sema_init (SEM, 1) is defined:

Platform: x86 32-bit

Kernel: 3.0.xx

Definition:

Linux/include/linux/semaphore.h  1 /*  2  * Copyright (c) 2008 Intel Corporation  3  * Author: Matthew Wilcox <willy@linux.intel.com>  4  *  5  * Distributed under the terms of the GNU GPL, version 2  6  *  7  * Please see kernel/semaphore.c for documentation of these functions  8  */  9 #ifndef __LINUX_SEMAPHORE_H 10 #define __LINUX_SEMAPHORE_H 11  12 #include <linux/list.h> 13 #include <linux/spinlock.h> 14  15 /* Please don't access any members of this structure directly */ 16 struct semaphore { 17         spinlock_t              lock; 18         unsigned int            count; 19         struct list_head        wait_list; 20 }; 21  22 #define __SEMAPHORE_INITIALIZER(name, n)                                \ 23 {                                                                       \ 24         .lock           = __SPIN_LOCK_UNLOCKED((name).lock),            \ 25         .count          = n,                                            \ 26         .wait_list      = LIST_HEAD_INIT((name).wait_list),             \ 27 } 28  29 #define DEFINE_SEMAPHORE(name)  \ 30         struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1) 31  32 static inline void sema_init(struct semaphore *sem, int val) 33 { 34         static struct lock_class_key __key; 35         *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); 36         lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0); 37 } 38  39 extern void down(struct semaphore *sem); 40 extern int __must_check down_interruptible(struct semaphore *sem); 41 extern int __must_check down_killable(struct semaphore *sem); 42 extern int __must_check down_trylock(struct semaphore *sem); 43 extern int __must_check down_timeout(struct semaphore *sem, long jiffies); 44 extern void up(struct semaphore *sem); 45  46 #endif /* __LINUX_SEMAPHORE_H */ 47