Re: [PATCH 4/7] [PATCH] Add target_pids parameter to alloc_pid()

["Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

Quoting Sukadev Bhattiprolu (sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org):
> 
> From: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> Date: Mon, 4 May 2009 01:17:42 -0700
> Subject: [PATCH 4/7] [PATCH] Add target_pids parameter to alloc_pid()
> 
> This parameter is currently NULL, but will be used in a follow-on patch.
> 
> Signed-off-by: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>

Acked-by: Serge Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

> ---
>  include/linux/pid.h |    2 +-
>  kernel/fork.c       |    3 ++-
>  kernel/pid.c        |    9 +++++++--
>  3 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/pid.h b/include/linux/pid.h
> index 49f1c2f..914185d 100644
> --- a/include/linux/pid.h
> +++ b/include/linux/pid.h
> @@ -119,7 +119,7 @@ extern struct pid *find_get_pid(int nr);
>  extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
>  int next_pidmap(struct pid_namespace *pid_ns, int last);
> 
> -extern struct pid *alloc_pid(struct pid_namespace *ns);
> +extern struct pid *alloc_pid(struct pid_namespace *ns, pid_t *target_pids);
>  extern void free_pid(struct pid *pid);
> 
>  /*
> diff --git a/kernel/fork.c b/kernel/fork.c
> index f8411a8..d2d69d3 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -954,6 +954,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
>  	int retval;
>  	struct task_struct *p;
>  	int cgroup_callbacks_done = 0;
> +	pid_t *target_pids = NULL;
> 
>  	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
>  		return ERR_PTR(-EINVAL);
> @@ -1119,7 +1120,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
>  		goto bad_fork_cleanup_io;
> 
>  	if (pid != &init_struct_pid) {
> -		pid = alloc_pid(p->nsproxy->pid_ns);
> +		pid = alloc_pid(p->nsproxy->pid_ns, target_pids);
>  		if (IS_ERR(pid)) {
>  			retval = PTR_ERR(pid);
>  			goto bad_fork_cleanup_io;
> diff --git a/kernel/pid.c b/kernel/pid.c
> index 93406c6..4b2373a 100644
> --- a/kernel/pid.c
> +++ b/kernel/pid.c
> @@ -279,13 +279,14 @@ void free_pid(struct pid *pid)
>  	call_rcu(&pid->rcu, delayed_put_pid);
>  }
> 
> -struct pid *alloc_pid(struct pid_namespace *ns)
> +struct pid *alloc_pid(struct pid_namespace *ns, pid_t *target_pids)
>  {
>  	struct pid *pid;
>  	enum pid_type type;
>  	int i, nr;
>  	struct pid_namespace *tmp;
>  	struct upid *upid;
> +	int tpid;
> 
>  	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
>  	if (!pid)
> @@ -293,7 +294,11 @@ struct pid *alloc_pid(struct pid_namespace *ns)
> 
>  	tmp = ns;
>  	for (i = ns->level; i >= 0; i--) {
> -		nr = alloc_pidmap(tmp, 0);
> +		tpid = 0;
> +		if (target_pids)
> +			tpid = target_pids[i];
> +
> +		nr = alloc_pidmap(tmp, tpid);
>  		if (nr < 0)
>  			goto out_free;
> 
> -- 
> 1.5.2.5