[CRIU] [PATCH 2/4] restore: TASK_HELPERs live until RESTORE stage

[Andrew Vagin]

On Fri, Sep 12, 2014 at 01:13:00PM -0500, Tycho Andersen wrote:
> In order to use TASK_HELPERS to open files from dead processes, they should
> persist until the end of the restore stage, so that the /proc files exist when
> setting up the fds.
> 
> This commit is in preparation for the remap_dead_pid commits.
> 
> v2: wait() on helpers after restore stage is over

[root at avagin-fc19-cr criu]#  bash test/zdtm.sh  ns/static/session00
================================= CRIU CHECK =================================
Error (timerfd.c:56): timerfd: No timerfd support for c/r: Inappropriate ioctl for device
============================= WARNING =============================
Not all features needed for CRIU are merged to upstream kernel yet,
so for now we maintain our own branch which can be cloned from:
git://git.kernel.org/pub/scm/linux/kernel/git/gorcunov/linux-cr.git
===================================================================
Execute zdtm/live/static/session00
./session00 --pidfile=session00.pid --outfile=session00.out
/root/git/criu/test
Dump 11182
Restore
test/zdtm.sh: line 564: 11220 Segmentation fault      setsid $CRIU restore -D $ddump -o restore.log -v4 -d $gen_args
Test: zdtm/live/static/session00, Result: FAIL
==================================== ERROR ====================================
Test: zdtm/live/static/session00, Namespace: 1
Dump log   : /root/git/criu/test/dump/static/session00/11182/1/dump.log
--------------------------------- grep Error ---------------------------------
------------------------------------- END -------------------------------------
Restore log: /root/git/criu/test/dump/static/session00/11182/1/restore.log
--------------------------------- grep Error ---------------------------------
(00.162581) Error (cr-restore.c:1738): BUG at cr-restore.c:1738
------------------------------------- END -------------------------------------
================================= ERROR OVER =================================

> 
> Signed-off-by: Tycho Andersen <tycho.andersen at canonical.com>
> ---
>  cr-restore.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/cr-restore.c b/cr-restore.c
> index 4d5ccd5..75d3afa 100644
> --- a/cr-restore.c
> +++ b/cr-restore.c
> @@ -702,7 +702,7 @@ static int pstree_wait_helpers()
>  {
>  	struct pstree_item *pi;
>  
> -	list_for_each_entry(pi, &current->children, sibling) {
> +	for_each_pstree_item(pi) {
>  		int status, ret;
>  
>  		if (pi->state != TASK_HELPER)
> @@ -770,9 +770,6 @@ static int restore_one_alive_task(int pid, CoreEntry *core)
>  
>  	rst_mem_switch_to_private();
>  
> -	if (pstree_wait_helpers())
> -		return -1;
> -
>  	if (prepare_fds(current))
>  		return -1;
>  
> @@ -931,9 +928,10 @@ static int restore_one_task(int pid, CoreEntry *core)
>  		ret = restore_one_alive_task(pid, core);
>  	else if (current->state == TASK_DEAD)
>  		ret = restore_one_zombie(pid, core);
> -	else if (current->state == TASK_HELPER)
> +	else if (current->state == TASK_HELPER) {
> +		restore_finish_stage(CR_STATE_RESTORE);
>  		ret = 0;
> -	else {
> +	} else {
>  		pr_err("Unknown state in code %d\n", (int)core->tc->task_state);
>  		ret = -1;
>  	}
> @@ -1711,6 +1709,9 @@ static int restore_root_task(struct pstree_item *init)
>  	if (ret < 0)
>  		goto out_kill;
>  
> +	if (pstree_wait_helpers() < 0)
> +		goto out_kill;
> +
>  	ret = run_scripts(ACT_POST_RESTORE);
>  	if (ret != 0) {
>  		pr_err("Aborting restore due to script ret code %d\n", ret);
> -- 
> 1.9.1
> 
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