kernel/exit.c

Source file repositories/reference/linux-study-clean/kernel/exit.c

File Facts

System
Linux kernel
Corpus path
kernel/exit.c
Extension
.c
Size
51651 bytes
Lines
2034
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_DEFINE1(exit, int, error_code)
{
	do_exit((error_code&0xff)<<8);
}

/*
 * Take down every thread in the group.  This is called by fatal signals
 * as well as by sys_exit_group (below).
 */
void __noreturn
do_group_exit(int exit_code)
{
	struct signal_struct *sig = current->signal;

	if (sig->flags & SIGNAL_GROUP_EXIT)
		exit_code = sig->group_exit_code;
	else if (sig->group_exec_task)
		exit_code = 0;
	else {
		struct sighand_struct *const sighand = current->sighand;

		spin_lock_irq(&sighand->siglock);
		if (sig->flags & SIGNAL_GROUP_EXIT)
			/* Another thread got here before we took the lock.  */
			exit_code = sig->group_exit_code;
		else if (sig->group_exec_task)
			exit_code = 0;
		else {
			sig->group_exit_code = exit_code;
			sig->flags = SIGNAL_GROUP_EXIT;
			zap_other_threads(current);
		}
		spin_unlock_irq(&sighand->siglock);
	}

	do_exit(exit_code);
	/* NOTREACHED */
}

/*
 * this kills every thread in the thread group. Note that any externally
 * wait4()-ing process will get the correct exit code - even if this
 * thread is not the thread group leader.
 */
SYSCALL_DEFINE1(exit_group, int, error_code)
{
	do_group_exit((error_code & 0xff) << 8);
	/* NOTREACHED */
	return 0;
}

static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
{
	return	wo->wo_type == PIDTYPE_MAX ||
		task_pid_type(p, wo->wo_type) == wo->wo_pid;
}

static int
eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
{
	if (!eligible_pid(wo, p))
		return 0;

	/*
	 * Wait for all children (clone and not) if __WALL is set or
	 * if it is traced by us.
	 */
	if (ptrace || (wo->wo_flags & __WALL))
		return 1;

	/*
	 * Otherwise, wait for clone children *only* if __WCLONE is set;
	 * otherwise, wait for non-clone children *only*.
	 *
	 * Note: a "clone" child here is one that reports to its parent
	 * using a signal other than SIGCHLD, or a non-leader thread which
	 * we can only see if it is traced by us.
	 */
	if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
		return 0;

	return 1;
}

/*
 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
 * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
 * the lock and this task is uninteresting.  If we return nonzero, we have
 * released the lock and the system call should return.
 */

Annotation

Implementation Notes