[CRIU] Re: [PATCH 06/14] pstree: Allow to dump and restore session non-leaders if --shell-job passed

[Pavel Emelyanov]

On 10/15/2012 06:54 PM, Cyrill Gorcunov wrote:
> 
> If --shell-job passed we allow to dump and restpre session non-leaders.
> 
> This slightly changes the behaviour or the tool. If previously
> we allowed to dump non-leaders after this commit we refuse to
> do that if not explicitly requested.
> 
> Note that in sake of tty restore (which will be addressed in
> further patches) we do inherit process group for root task.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>  include/pstree.h |    8 +++++
>  pstree.c         |   92 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 98 insertions(+), 2 deletions(-)
> 


> @@ -61,4 +68,5 @@ extern int dump_pstree(struct pstree_item *root_item);
>  
>  struct task_entries;
>  extern struct task_entries *task_entries;
> +
>  #endif

Trash

> +	if (root_item->pid.virt != root_item->sid) {
> +		if (!opts.shell_job) {
> +			pr_err("The root process %d is not a session leader, "
> +			       "miss to specify %s option?\n",
> +			       item->pid.virt, "--shell-job");

%s for hard-coded string is strange. Declare a macro for it and use it here and
in the --help message.

> +			return -1;
> +		}
> +

> +		 *   PID  GID  SID
> +		 *    4    3    2    root-task
> +		 *    5    3    2    `- task-1
> +		 *    6    6    2    `- task-2
> +		 *
> +		 * So when we migrate a shell job we need the task-1 to inherit
> +		 * GID from root task, thus we put INHERIT_PGID in the image.
> +		 */
> +		if (item->pgid == origin_sid)
> +			e.pgid = INHERIT_SID;

His case is not described in the comment above.

> +		else if (item->pgid == origin_pgid)
> +			e.pgid = INHERIT_PGID;
> +		else
> +			e.pgid = item->pgid;

> @@ -102,6 +158,16 @@ int dump_pstree(struct pstree_item *root_item)
>  	ret = 0;
>  
>  err:
> +
> +	/*
> +	 * Don't forget to restore changed values, we keep
> +	 * process tree solid in memory.

Where did we change them?

> +	 */
> +	if (origin_sid != INHERIT_SID) {
> +		root_item->sid = origin_sid;
> +		root_item->pgid = origin_pgid;
> +	}
> +
>  	pr_info("----------------------------------------\n");
>  	close(pstree_fd);
>  	return ret;

> struct pstree_item *root_item;
>  
> +static pid_t current_sid = INHERIT_SID;
> +static pid_t current_pgid = INHERIT_PGID;
> +

These two are not used outside of the prepare_pstree() and _ids() and the
latter can be directly called from the former. Thus no need in two more
global variables.