linux-master/kernel/fork.c

104 #include <uapi/linux/pidfd.h>
1993  * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
1994  * @pid:   the struct pid for which to create a pidfd
1995  * @flags: flags of the new @pidfd
1996  * @ret: Where to return the file for the pidfd.
1998  * Allocate a new file that stashes @pid and reserve a new pidfd number in the
1999  * caller's file descriptor table. The pidfd is reserved but not installed yet.
2002  * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
2003  * pidfd file are prepared.
2006  * call fd_install() passing the returned pidfd and pidfd file as arguments in
2007  * order to install the pidfd into its file descriptor table or they must use
2008  * put_unused_fd() and fput() on the returned pidfd and pidfd file
2011  * This function is useful when a pidfd must already be reserved but there
2013  * that no pidfd is leaked into its file descriptor table.
2015  * Return: On success, a reserved pidfd is returned from the function and a new
2016  *         pidfd file is returned in the last argument to the function. On
2022 	int pidfd;
2025 	pidfd = get_unused_fd_flags(O_CLOEXEC);
2026 	if (pidfd < 0)
2027 		return pidfd;
2031 		put_unused_fd(pidfd);
2040 	return pidfd;
2044  * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2045  * @pid:   the struct pid for which to create a pidfd
2046  * @flags: flags of the new @pidfd
2047  * @ret: Where to return the pidfd.
2049  * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2050  * caller's file descriptor table. The pidfd is reserved but not installed yet.
2056  * call fd_install() passing the returned pidfd and pidfd file as arguments in
2057  * order to install the pidfd into its file descriptor table or they must use
2058  * put_unused_fd() and fput() on the returned pidfd and pidfd file
2061  * This function is useful when a pidfd must already be reserved but there
2063  * that no pidfd is leaked into its file descriptor table.
2065  * Return: On success, a reserved pidfd is returned from the function and a new
2066  *         pidfd file is returned in the last argument to the function. On
2140 	int pidfd = -1, retval;
2416 	 * descriptor table (so that the pidfd doesn't leak into the child
2426 		pidfd = retval;
2428 		retval = put_user(pidfd, args->pidfd);
2610 		fd_install(pidfd, pidfile);
2633 		put_unused_fd(pidfd);
2767 	 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2776 	    (args->pidfd == args->parent_tid))
2932 		.pidfd		= parent_tidptr,
2994 		.pidfd		= u64_to_user_ptr(args.pidfd),