cgroup: restructure the failure path in cgroup_write_event_control()

static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,

				      const char *buffer)

{

	struct cgroup_event *event = NULL;

	struct cgroup_event *event;

	struct cgroup *cgrp_cfile;

	unsigned int efd, cfd;

	struct file *efile = NULL;

	struct file *cfile = NULL;

	struct file *efile;

	struct file *cfile;

	char *endp;

	int ret;

	efile = eventfd_fget(efd);

	if (IS_ERR(efile)) {

		ret = PTR_ERR(efile);

		goto fail;

		goto out_kfree;

	}

	event->eventfd = eventfd_ctx_fileget(efile);

	if (IS_ERR(event->eventfd)) {

		ret = PTR_ERR(event->eventfd);

		goto fail;

		goto out_put_efile;

	}

	cfile = fget(cfd);

	if (!cfile) {

		ret = -EBADF;

		goto fail;

		goto out_put_eventfd;

	}

	/* the process need read permission on control file */

	/* AV: shouldn't we check that it's been opened for read instead? */

	ret = inode_permission(file_inode(cfile), MAY_READ);

	if (ret < 0)

		goto fail;

		goto out_put_cfile;

	event->cft = __file_cft(cfile);

	if (IS_ERR(event->cft)) {

		ret = PTR_ERR(event->cft);

		goto fail;

		goto out_put_cfile;

	}

	/*

	cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);

	if (cgrp_cfile != cgrp) {

		ret = -EINVAL;

		goto fail;

		goto out_put_cfile;

	}

	if (!event->cft->register_event || !event->cft->unregister_event) {

		ret = -EINVAL;

		goto fail;

		goto out_put_cfile;

	}

	ret = event->cft->register_event(cgrp, event->cft,

			event->eventfd, buffer);

	if (ret)

		goto fail;

		goto out_put_cfile;

	efile->f_op->poll(efile, &event->pt);

	return 0;

fail:

	if (cfile)

out_put_cfile:

	fput(cfile);

	if (event && event->eventfd && !IS_ERR(event->eventfd))

out_put_eventfd:

	eventfd_ctx_put(event->eventfd);

	if (!IS_ERR_OR_NULL(efile))

out_put_efile:

	fput(efile);

out_kfree:

	kfree(event);

	return ret;