Linux内核中的pthread_mutex_lock和pthread_cond_wait的等价物

Question

linux内核中的pthread_mutex_lock和pthread_cond_wait的等效物是什么。以及如何使用它们。你能否提供简单的（hello world）例子。

Answer 1

• 互斥体（如阿尔斯说）：

mutex_lock()和mutex_unlock()我们应该初始化互斥我们与mutex_init()使用它之前（从#include <linux/mutex.h>）

• 对于相当于

wait_event_interruptible()和wake_up_interruptible()我们应该初始化与init_waitqueue_head()（从#include <linux/wait.h>）

Answer 2

因为内核模块直接链接到内核，所以不能在内核空间中使用任何库调用。

您可以使用：

mutex_lock() & mutex_unlock()

它们通过提供：linux/mutex.h

Answer 3

我为Linux内核编程不久前（1999-ISH）一个互斥体和条件库和自那以后用于各种项目。

我称之为LMC（linux mutexes和条件变量）。这是在内核中有一个互斥体类型之前。

http://www.kylheku.com/~kaz/lmc.html

最近，我添加了一个很酷的新功能，其语义是“放弃互斥体，以等待条件变量，和同时轮询多个文件描述符，直到达到给定的超时。”

我在内核线程中使用了这个内核线程，该线程监视各种共享对象的更新，并同时与内核套接字进行通信。

检查出来：

/** 
* Atomically give up the mutex and wait on the condition variable. 
* Wake up if the specified timeout elapses, or if a signal is delivered. 
* Additionally, also wait on the specified file descriptors to become 
* ready, combining condition waiting with poll(). 
* KCOND_WAIT_SUCCESS means the condition was signaled, or one or more 
* file descriptors are ready. 
* Also, a negative value can be returned indicating an error! 
* (The poll needs to dynamically allocate some memory for the wait table). 
* The timeout is relative to the current time, specifying how long to sleep in 
* jiffies (CPU clock ticks). 
*/ 
int kcond_timed_wait_rel_poll(kcond_t *, kmutex_t *, long, 
           kcond_poll_t *, unsigned int); 

kcond_poll_t结构数组是你必须创建和你自己填写的东西，以及结构如下所示。有一个类型字段，以便您可以等待或者套接字（struct socket *）或文件（struct file *）：

/** 
* Structure for file-descriptor polling condition waits. 
* This resembles struct pollfd, but uses a direct file descriptor 
* pointer rather than a file descriptor number. Also, 
* it contains the wait queue by which the process is enqueued 
* to wait on that descriptor. Thus our poll function doesn't 
* have to dynamically allocate wait queue tables. It gets 
* them from this array! (But this means that the array cannot 
* be used by multiple threads at the same time to do polling!) 
*/ 
typedef struct { 
     kcond_poll_type_t type; /* Must set this. */ 
     union {     /* Must set union field according to type. */ 
       struct file *file;  
       struct socket *sock; 
     } obj; 
     short events;   /* And this. */ 
     short revents;   /* Check response in this. */ 
     wait_queue_t wait;   /* Internal, don't set. */ 
     wait_queue_head_t *queue; /* Internal, don't set */ 
} kcond_poll_t;