ioctl

//user spaceint ioctl(int fd,unsigned long cmd,...);//kernel spaceint (*ioctl)(struct inode *inode,struct file* filp,unsigned int cmd,unsigned long arg)

Blocking I/O

#include <linux/wait.h>wait_queue_head_t my_queue;DECLARE_WAIT_QUEUE_HEAD(name);init_waitqueue_head(&my_queue);

wait_event(queue,condition);wait_event_interruptible(queue,condition);wait_event_timeout(queue,condition,timeout);wait_event_interruptible_timeout(queue,condition,timeout);void wake_up(wait_queue_head_t *queue);void wake_up_interruptible(wait_queue_head_t *queue);

Manual sleeps

DEFINE_WAIT(my_wait);void prepare_to_wait(wait_queue_head_t *queue,wait_queue_t *wait,int state);void schedule();//combine with condition check void finish_wait(wait_queue_head_t *queue,wait_queue_t *wait);

poll and select

unsigned int (*poll)(struct file *filp,struct poll_table *wait);

eg:

static unsigned int scull_p_poll(struct file *filp, poll_table *wait){    struct scull_pipe *dev = filp->private_data;    unsigned int mask = 0;    /*    * The buffer is circular; it is considered full    * if "wp" is right behind "rp" and empty if the    * two are equal.    */    down(&dev->sem);    poll_wait(filp, &dev->inq, wait);    poll_wait(filp, &dev->outq, wait);    if (dev->rp != dev->wp)        mask |= POLLIN | POLLRDNORM; /* readable */    if (spacefree(dev))        mask |= POLLOUT | POLLWRNORM; /* writable */    up(&dev->sem);    return mask;}