[lxc-devel] [PATCH 1/2] lxc-start: fix the container leak when daemonize

[Serge Hallyn]

Quoting Qiang Huang (h.huangqiang at huawei.com):
> When start container with daemon model, we'll have a new daemon
> process in lxcapi_start, whose c->numthreads is 2, inherited
> from his father. Even his father return to main(), the
> lxc_container_put won't affect son's numthreads.

The memlock is only between threads.  But the child is fork()ed, so the
lxc_container_put() of one won't affect the other task.

Now maybe wait_on_daemonized_start() should be doing an
lxc_container_put()?

> So when daemon stops, he should return to main and do
> lxc_container_put again, rather than exit and leave the
> container alone.

I disagree.  This means two separate processes will continue at the
point where lxcapi_start() was called.  That sounds like a recipe for
disaster.

> Signed-off-by: Qiang Huang <h.huangqiang at huawei.com>

I'm basically out this week and may not be thinking about it rightly,
but I'm going to say

Nacked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

in the hopes that someone with enough time will reconsider.

> ---
>  src/lxc/lxccontainer.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index 0bebdff..ddea0d7 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -632,12 +632,10 @@ reboot:
>  		goto reboot;
>  	}
> 
> -	if (daemonize) {
> +	if (daemonize)
>  		lxc_container_put(c);
> -		exit (ret == 0 ? true : false);
> -	} else {
> -		return (ret == 0 ? true : false);
> -	}
> +	
> +	return (ret == 0 ? true : false);
>  }
> 
>  /*
> -- 
> 1.8.3
>