[CRIU] [PATCH] restore: add action scripts setup-namespaces (v2)

[Pavel Emelyanov]

On 05/31/2013 02:29 PM, Andrey Vagin wrote:
> After creating namespaces we may need to apply some configuration.
> For example uid and gid maps should be applied in this moment.
> 
> This script should be executed from crtools, but namespaces are created
> in a root process, so we need to add a new stage for synchronizing.
> 
> v2: use a separate stage instead of socketpair.
> 
> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  cr-restore.c       | 46 ++++++++++++++++++++++++++++++++++++++++++----
>  include/restorer.h |  1 +
>  2 files changed, 43 insertions(+), 4 deletions(-)
> 
> diff --git a/cr-restore.c b/cr-restore.c
> index 70c5e68..8983f4c 100644
> --- a/cr-restore.c
> +++ b/cr-restore.c
> @@ -931,6 +931,14 @@ static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
>  
>  	exit = (siginfo->si_code == CLD_EXITED);
>  	status = siginfo->si_status;
> +
> +	/* skip scripts */
> +	if (!current && root_item->pid.real != pid) {
> +		pid = waitpid(root_item->pid.real, &status, WNOHANG);

Shouldn't while () loop be here?

> +		if (pid <= 0)
> +			return;
> +	}
> +
>  	if (!current || status)
>  		goto err;
>  
> @@ -1091,6 +1099,8 @@ static int restore_task_with_children(void *_arg)
>  		if (mount_proc())
>  			exit(1);
>  
> +		restore_finish_stage(CR_STATE_RESTORE_NS);
> +
>  		if (root_prepare_shared())
>  			exit(1);
>  	}
> @@ -1158,6 +1168,8 @@ static int restore_task_with_children(void *_arg)
>  static inline int stage_participants(int next_stage)
>  {
>  	switch (next_stage) {
> +	case CR_STATE_RESTORE_NS:
> +		return 1;
>  	case CR_STATE_FORKING:
>  		return task_entries->nr_tasks + task_entries->nr_helpers;
>  	case CR_STATE_RESTORE_PGID:
> @@ -1173,7 +1185,7 @@ static inline int stage_participants(int next_stage)
>  	return -1;
>  }
>  
> -static int restore_switch_stage(int next_stage)
> +static int restore_wait_inprogress_tasks()
>  {
>  	int ret;
>  	futex_t *np = &task_entries->nr_in_progress;
> @@ -1183,7 +1195,19 @@ static int restore_switch_stage(int next_stage)
>  	if (ret < 0)
>  		return ret;
>  
> -	futex_set(np, stage_participants(next_stage));
> +	return 0;
> +}
> +
> +static int restore_switch_stage(int next_stage)
> +{
> +	int ret;
> +
> +	ret = restore_wait_inprogress_tasks();
> +	if (ret)
> +		return ret;
> +
> +	futex_set(&task_entries->nr_in_progress,
> +			stage_participants(next_stage));
>  	futex_set_and_wake(&task_entries->start, next_stage);
>  	return 0;
>  }
> @@ -1230,12 +1254,26 @@ static int restore_root_task(struct pstree_item *init)
>  		return -1;
>  	}
>  
> -	futex_set(&task_entries->nr_in_progress, stage_participants(CR_STATE_FORKING));
> +	futex_set(&task_entries->nr_in_progress,
> +			stage_participants(CR_STATE_RESTORE_NS));
>  
>  	ret = fork_with_pid(init);
>  	if (ret < 0)
>  		return -1;
>  
> +	pr_info("Wait until namespaces are created\n");
> +	ret = restore_wait_inprogress_tasks();
> +	if (ret)
> +		goto out;
> +
> +	ret = run_scripts("setup-namespaces");
> +	if (ret)
> +		goto out;
> +
> +	ret = restore_switch_stage(CR_STATE_FORKING);

This will call "wait-inprogress" again. Can we tune this thing out?

> +	if (ret < 0)
> +		goto out;
> +
>  	pr_info("Wait until all tasks are forked\n");
>  	ret = restore_switch_stage(CR_STATE_RESTORE_PGID);
>  	if (ret < 0)
> @@ -1303,7 +1341,7 @@ static int prepare_task_entries()
>  	task_entries->nr_threads = 0;
>  	task_entries->nr_tasks = 0;
>  	task_entries->nr_helpers = 0;
> -	futex_set(&task_entries->start, CR_STATE_FORKING);
> +	futex_set(&task_entries->start, CR_STATE_RESTORE_NS);
>  	mutex_init(&task_entries->zombie_lock);
>  
>  	return 0;
> diff --git a/include/restorer.h b/include/restorer.h
> index caee41d..a5c0667 100644
> --- a/include/restorer.h
> +++ b/include/restorer.h
> @@ -162,6 +162,7 @@ struct shmems {
>  #define TASK_ENTRIES_SIZE 4096
>  
>  enum {
> +	CR_STATE_RESTORE_NS, /* is used for executing "setup-namespace" scripts */
>  	CR_STATE_FORKING,
>  	CR_STATE_RESTORE_PGID,
>  	CR_STATE_RESTORE,
>