How to implement thread mutex with kthread?

Question

I know that we can use pthread_mutex_init and pthread_mutex_lock to implement thread mutual exclusion. But how can I implement it in kernel module with kthread?

Answer 1

You cannot use the pthread_mutex_* functions as these are userspace-only calls. In the kernel use the use the mutexes provided by linux/mutex.h:

struct mutex my_mutex; /* shared between the threads */

mutex_init(&my_mutex); /* called only ONCE */

/* inside a thread */
mutex_lock(&my_mutex);
/* do the work with the data you're protecting */
mutex_unlock(&my_mutex);