how to used wait_event_interruptible_timeout

`wait_event_interruptible_timeout` is a function in the Linux kernel that allows a process to sleep until a certain condition is met or a timeout expires. The function prototype is as follows:

unsigned long wait_event_interruptible_timeout(wait_queue_head_t *q, int condition, unsigned long timeout);

Here are the parameters:

- `wait_queue_head_t *q`: A pointer to the wait queue head associated with the condition that the process is waiting for.
- `int condition`: The condition that the process is waiting for. The condition is typically a boolean expression that becomes true when some event occurs.
- `unsigned long timeout`: The maximum time in jiffies that the process will wait for the condition to become true. If the condition is not met by the timeout, the function returns 0.

Here's an example of how to use `wait_event_interruptible_timeout`:

#include <linux/wait.h>
#include <linux/sched.h>

DECLARE_WAIT_QUEUE_HEAD(my_wait_queue);

int my_condition = 0;

void my_function(void) {
    unsigned long timeout = msecs_to_jiffies(5000); // wait for up to 5 seconds
    int ret;

    while (!my_condition) {
        ret = wait_event_interruptible_timeout(my_wait_queue, my_condition, timeout);

        if (ret == -ERESTARTSYS) {
            // interrupted by a signal, handle the signal here
        } else if (ret == 0) {
            // timeout expired, handle the timeout here
        } else {
            // condition became true, handle the event here
        }
    }
}

In this example, `my_function` waits for `my_condition` to become true by calling `wait_event_interruptible_timeout` with a timeout of 5 seconds. The function sleeps until either the condition becomes true, the timeout expires, or it is interrupted by a signal. The return value of `wait_event_interruptible_timeout` indicates whether the condition became true, the timeout expired, or the function was interrupted by a signal.