[CRIU] [RFC PATCH v2 20/23] lazy-pages: handle UFFD_EVENT_EXIT

[Pavel Emelyanov]

On 02/06/2017 02:44 PM, Mike Rapoport wrote:
> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
> ---
>  criu/uffd.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/criu/uffd.c b/criu/uffd.c
> index 6ac34f7..f2a6bfa 100644
> --- a/criu/uffd.c
> +++ b/criu/uffd.c
> @@ -87,6 +87,8 @@ struct lazy_pages_info {
>  };
>  
>  static LIST_HEAD(lpis);
> +static LIST_HEAD(exiting_lpis);
> +
>  static int handle_uffd_event(struct epoll_rfd *lpfd);
>  
>  static struct lazy_pages_info *lpi_init(void)
> @@ -106,15 +108,23 @@ static struct lazy_pages_info *lpi_init(void)
>  	return lpi;
>  }
>  
> -static void lpi_fini(struct lazy_pages_info *lpi)
> +static void free_lazy_iovs(struct lazy_pages_info *lpi)
>  {
>  	struct lazy_iov *p, *n;
>  
> +	list_for_each_entry_safe(p, n, &lpi->iovs, l) {
> +		list_del(&p->l);
> +		xfree(p);
> +	}
> +}
> +
> +static void lpi_fini(struct lazy_pages_info *lpi)
> +{
> +
>  	if (!lpi)
>  		return;
>  	free(lpi->buf);
> -	list_for_each_entry_safe(p, n, &lpi->iovs, l)
> -		xfree(p);
> +	free_lazy_iovs(lpi);
>  	if (lpi->lpfd.fd > 0)
>  		close(lpi->lpfd.fd);
>  	if (lpi->pr.close)
> @@ -797,6 +807,29 @@ static int handle_remap(struct lazy_pages_info *lpi, struct uffd_msg *msg)
>  	return remap_lazy_iovs(lpi, from, to, len);
>  }
>  
> +static int handle_exit(struct lazy_pages_info *lpi, struct uffd_msg *msg)
> +{
> +	lp_debug(lpi, "EXIT\n");
> +	list_move(&lpi->l, &exiting_lpis);

Why not kill it right here? What do we wait for epoll event on this
guy to call complete_exits()?

> +	return 1;
> +}
> +
> +static int complete_exits(int epollfd)
> +{
> +	struct lazy_pages_info *lpi, *n;
> +
> +	list_for_each_entry_safe(lpi, n, &exiting_lpis, l) {
> +		if (epoll_del_rfd(epollfd, &lpi->lpfd))
> +			return -1;
> +		free_lazy_iovs(lpi);
> +		close(lpi->lpfd.fd);
> +		/* keep it for summary */
> +		list_move_tail(&lpi->l, &lpis);
> +	}
> +
> +	return 0;
> +}
> +
>  static int handle_page_fault(struct lazy_pages_info *lpi, struct uffd_msg *msg)
>  {
>  	struct lp_req *req;
> @@ -863,6 +896,8 @@ static int handle_uffd_event(struct epoll_rfd *lpfd)
>  		return handle_remove(lpi, &msg);
>  	case UFFD_EVENT_REMAP:
>  		return handle_remap(lpi, &msg);
> +	case UFFD_EVENT_EXIT:
> +		return handle_exit(lpi, &msg);
>  	default:
>  		lp_err(lpi, "unexpected uffd event %u\n", msg.event);
>  		return -1;
> @@ -902,6 +937,11 @@ static int handle_requests(int epollfd, struct epoll_event *events, int nr_fds)
>  		ret = epoll_run_rfds(epollfd, events, nr_fds, poll_timeout);
>  		if (ret < 0)
>  			goto out;
> +		if (ret > 0) {
> +			if (complete_exits(epollfd))
> +				return -1;
> +			continue;
> +		}
>  
>  		if (poll_timeout)
>  			pr_debug("Start handling remaining pages\n");
>