[CRIU] [PATCH] tty: restore sid on master points only

[Cyrill Gorcunov]

On Tue, Mar 19, 2013 at 07:13:35PM +0400, Andrey Vagin wrote:
> If a master point has sid, it doesn't mean, that all slave points
> will have sid. Look at tty03 for example:
> 
>   PID   SID TT       COMMAND
> 26748 26748 ?        tty03
> 26749 26749 pts/2     \_ tty03
> 26750 26750 ?             \_ tty03
> 
> The second process has not a file descriptor for the ctl tty,
> but this tty is opened in tty03.
> 
> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  test/zdtm.sh | 1 +
>  tty.c        | 6 ++----
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/test/zdtm.sh b/test/zdtm.sh
> index 3ecba36..4163282 100755
> --- a/test/zdtm.sh
> +++ b/test/zdtm.sh
> @@ -73,6 +73,7 @@ static/pty00
>  static/pty01
>  static/pty04
>  static/tty02
> +static/tty03
>  static/child_opened_proc
>  static/cow01
>  static/fpu00
> diff --git a/tty.c b/tty.c
> index 251930b..a9cc11a 100644
> --- a/tty.c
> +++ b/tty.c
> @@ -731,10 +731,8 @@ static int tty_find_restoring_task(struct tty_info *info)
>  	}
>  
>  	if (info->tie->sid) {
> -		if (pty_is_master(info)) {
> -			if (tty_has_active_pair(info))
> -				return 0;
> -		}
> +		if (!pty_is_master(info))
> +			return 0;

Lets imagine another situation -- we have 2 tasks, where second is forked

task1			task2
-----			-----
ptm = open ptmx
pts = open pts

setsid()
			fork()
			close(ptm)
close(pts)

--- c/r session for task2 only ---

task2 has only one tty-info with some sid,
in the code about we see it's not master anymore
and simply return 0, would it work? There should be a message
but I guess it won't appear with this patch applied.

	pr_err("No task found with sid %d\n", info->tie->sid);

Did I miss something?