static void write_sigio_workaround()

in os-Linux/sigio.c [274:355]

• 64 lines of code
• 8 McCabe index (conditional complexity)

static void write_sigio_workaround(void)
{
	struct pollfd *p;
	int err;
	int l_write_sigio_fds[2];
	int l_sigio_private[2];
	int l_write_sigio_pid;

	/* We call this *tons* of times - and most ones we must just fail. */
	sigio_lock();
	l_write_sigio_pid = write_sigio_pid;
	sigio_unlock();

	if (l_write_sigio_pid != -1)
		return;

	err = os_pipe(l_write_sigio_fds, 1, 1);
	if (err < 0) {
		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
		       "err = %d\n", -err);
		return;
	}
	err = os_pipe(l_sigio_private, 1, 1);
	if (err < 0) {
		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
		       "err = %d\n", -err);
		goto out_close1;
	}

	p = setup_initial_poll(l_sigio_private[1]);
	if (!p)
		goto out_close2;

	sigio_lock();

	/*
	 * Did we race? Don't try to optimize this, please, it's not so likely
	 * to happen, and no more than once at the boot.
	 */
	if (write_sigio_pid != -1)
		goto out_free;

	current_poll = ((struct pollfds) { .poll 	= p,
					   .used 	= 1,
					   .size 	= 1 });

	if (write_sigio_irq(l_write_sigio_fds[0]))
		goto out_clear_poll;

	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));

	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
					    CLONE_FILES | CLONE_VM,
					    &write_sigio_stack);

	if (write_sigio_pid < 0)
		goto out_clear;

	sigio_unlock();
	return;

out_clear:
	write_sigio_pid = -1;
	write_sigio_fds[0] = -1;
	write_sigio_fds[1] = -1;
	sigio_private[0] = -1;
	sigio_private[1] = -1;
out_clear_poll:
	current_poll = ((struct pollfds) { .poll	= NULL,
					   .size	= 0,
					   .used	= 0 });
out_free:
	sigio_unlock();
	kfree(p);
out_close2:
	close(l_sigio_private[0]);
	close(l_sigio_private[1]);
out_close1:
	close(l_write_sigio_fds[0]);
	close(l_write_sigio_fds[1]);
}