linux/kernel/exit.c

1719 int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid,
1739 		if (upid <= 0)
1742 		pid = find_get_pid(upid);
1746 		if (upid < 0)
1749 		if (upid)
1750 			pid = find_get_pid(upid);
1756 		if (upid < 0)
1759 		pid = pidfd_get_pid(upid, &f_flags);
1779 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1785 	ret = kernel_waitid_prepare(&wo, which, upid, infop, options, ru);
1797 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1802 	long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1830 long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1843 	if (upid == INT_MIN)
1846 	if (upid == -1)
1848 	else if (upid < 0) {
1850 		pid = find_get_pid(-upid);
1851 	} else if (upid == 0) {
1854 	} else /* upid > 0 */ {
1856 		pid = find_get_pid(upid);
1889 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1893 	long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);