[CRIU] [PATCH 2/2] files: Fix breaking of fds list ordering by splice

[Pavel Begunkov]

Kirill, could you pls take a look?

The basic idea is to preserve the order of the final list. The
'completed' list is split into 2 separate lists by #1a945c9, but the
final splicing may break the order. As a simplest solution, I just
returned it to the single list version.
Should they really be explicitly separated? Then there should be some
actual merge. Or maybe it's already sorted?

On Fri, Jun 30, 2017 at 10:29 PM, Pavel Begunkov <asml.silence at gmail.com> wrote:
> fds lists should be sorted in ascending order, splicing of 2 (ordered)
> lists violates this invariant.
>
> Signed-off-by: Pavel Begunkov <asml.silence at gmail.com>
> ---
>  criu/files.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/criu/files.c b/criu/files.c
> index 4a263c438..a0df8f531 100644
> --- a/criu/files.c
> +++ b/criu/files.c
> @@ -1161,12 +1161,13 @@ static int receive_fd(struct fdinfo_list_entry *fle)
>         return 0;
>  }
>
> -static void close_fdinfos(struct list_head *list)
> +static void close_fake_fdinfos(struct list_head *list)
>  {
>         struct fdinfo_list_entry *fle;
>
>         list_for_each_entry(fle, list, ps_list)
> -               close(fle->fe->fd);
> +               if (fle->fake)
> +                       close(fle->fe->fd);
>  }
>
>  static int open_fdinfos(struct pstree_item *me)
> @@ -1174,7 +1175,6 @@ static int open_fdinfos(struct pstree_item *me)
>         struct list_head *list = &rsti(me)->fds;
>         struct fdinfo_list_entry *fle, *tmp;
>         LIST_HEAD(completed);
> -       LIST_HEAD(fake);
>         bool progress, again;
>         int st, ret = 0;
>
> @@ -1197,10 +1197,7 @@ static int open_fdinfos(struct pstree_item *me)
>                                  * and reduce number of fles in their checks.
>                                  */
>                                 list_del(&fle->ps_list);
> -                               if (!fle->fake)
> -                                       list_add_tail(&fle->ps_list, &completed);
> -                               else
> -                                       list_add_tail(&fle->ps_list, &fake);
> +                               list_add_tail(&fle->ps_list, &completed);
>                         }
>                         if (ret == 1)
>                                again = true;
> @@ -1214,9 +1211,8 @@ static int open_fdinfos(struct pstree_item *me)
>          * Fake fles may be used for restore other
>          * file types, so their closing is delayed.
>          */
> -       close_fdinfos(&fake);
> +       close_fake_fdinfos(&completed);
>  splice:
> -       list_splice(&fake, list);
>         list_splice(&completed, list);
>
>         return ret;
> --
> 2.11.1
>