Function pipeclose

freebsd/kern/sys_pipe.c:1621–1692

* shutdown the pipe */

 * shutdown the pipe
 */
static void
pipeclose(struct pipe *cpipe)
{
	struct pipepair *pp;
	struct pipe *ppipe;

	KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));

	PIPE_LOCK(cpipe);
	pipelock(cpipe, 0);
	pp = cpipe->pipe_pair;

	/*
	 * If the other side is blocked, wake it up saying that
	 * we want to close it down.
	 */
	cpipe->pipe_state |= PIPE_EOF;
	while (cpipe->pipe_busy) {
		wakeup(cpipe);
		cpipe->pipe_state |= PIPE_WANT;
		pipeunlock(cpipe);
		msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
		pipelock(cpipe, 0);
	}

	pipeselwakeup(cpipe);

	/*
	 * Disconnect from peer, if any.
	 */
	ppipe = cpipe->pipe_peer;
	if (ppipe->pipe_present == PIPE_ACTIVE) {
		ppipe->pipe_state |= PIPE_EOF;
		wakeup(ppipe);
		pipeselwakeup(ppipe);
	}

	/*
	 * Mark this endpoint as free.  Release kmem resources.  We
	 * don't mark this endpoint as unused until we've finished
	 * doing that, or the pipe might disappear out from under
	 * us.
	 */
	PIPE_UNLOCK(cpipe);
	pipe_free_kmem(cpipe);
	PIPE_LOCK(cpipe);
	cpipe->pipe_present = PIPE_CLOSING;
	pipeunlock(cpipe);

	/*
	 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
	 * PIPE_FINALIZED, that allows other end to free the
	 * pipe_pair, only after the knotes are completely dismantled.
	 */
	knlist_clear(&cpipe->pipe_sel.si_note, 1);
	cpipe->pipe_present = PIPE_FINALIZED;
	seldrain(&cpipe->pipe_sel);
	knlist_destroy(&cpipe->pipe_sel.si_note);