kernel/time/posix-stubs.c

Source file repositories/reference/linux-study-clean/kernel/time/posix-stubs.c

File Facts

System
Linux kernel
Corpus path
kernel/time/posix-stubs.c
Extension
.c
Size
4747 bytes
Lines
210
Domain
Core OS
Bucket
Scheduler, Processes, Timers, Sync, And Syscalls
Inferred role
Core OS: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
		const struct __kernel_timespec __user *, tp)
{
	struct timespec64 new_tp;

	if (which_clock != CLOCK_REALTIME)
		return -EINVAL;
	if (get_timespec64(&new_tp, tp))
		return -EFAULT;

	return do_sys_settimeofday64(&new_tp, NULL);
}

static int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
{
	switch (which_clock) {
	case CLOCK_REALTIME:
		ktime_get_real_ts64(tp);
		break;
	case CLOCK_MONOTONIC:
		ktime_get_ts64(tp);
		timens_add_monotonic(tp);
		break;
	case CLOCK_BOOTTIME:
		ktime_get_boottime_ts64(tp);
		timens_add_boottime(tp);
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
		struct __kernel_timespec __user *, tp)
{
	int ret;
	struct timespec64 kernel_tp;

	ret = do_clock_gettime(which_clock, &kernel_tp);
	if (ret)
		return ret;

	if (put_timespec64(&kernel_tp, tp))
		return -EFAULT;
	return 0;
}

SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, struct __kernel_timespec __user *, tp)
{
	struct timespec64 rtn_tp = {
		.tv_sec = 0,
		.tv_nsec = hrtimer_resolution,
	};

	switch (which_clock) {
	case CLOCK_REALTIME:
	case CLOCK_MONOTONIC:
	case CLOCK_BOOTTIME:
		if (put_timespec64(&rtn_tp, tp))
			return -EFAULT;
		return 0;
	default:
		return -EINVAL;
	}
}

SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
		const struct __kernel_timespec __user *, rqtp,
		struct __kernel_timespec __user *, rmtp)
{
	struct timespec64 t;
	ktime_t texp;

	switch (which_clock) {
	case CLOCK_REALTIME:
	case CLOCK_MONOTONIC:
	case CLOCK_BOOTTIME:
		break;
	default:
		return -EINVAL;
	}

	if (get_timespec64(&t, rqtp))
		return -EFAULT;
	if (!timespec64_valid(&t))
		return -EINVAL;
	if (flags & TIMER_ABSTIME)
		rmtp = NULL;

Annotation

Implementation Notes