On Wed, 03 Oct 2007 18:19:01 +0400 Pavel Emelyanov wrote:

> This is a pid which is attached to tasks when they detach
> their pids. This is done in detach_pid() and transfer_pid().
> The pid_alive() check is changed to reflect this fact.
> 
> Signed-off-by: Pavel Emelyanov <[EMAIL PROTECTED]>
> 
> ---
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 4f21af1..e17b8f8 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1286,9 +1286,11 @@ static inline pid_t task_ppid_nr_ns(stru
>   * If pid_alive fails, then pointers within the task structure
>   * can be stale and must not be dereferenced.
>   */
> +extern struct pid dummy_pid;
> +
>  static inline int pid_alive(struct task_struct *p)
>  {
> -     return p->pids[PIDTYPE_PID].pid != NULL;
> +     return p->pids[PIDTYPE_PID].pid != &dummy_pid;
>  }
>  
>  /**
> diff --git a/kernel/pid.c b/kernel/pid.c
> index d7388d7..b7a11cf 100644
> --- a/kernel/pid.c
> +++ b/kernel/pid.c
> @@ -81,6 +81,17 @@ struct pid_namespace init_pid_ns = {
>  };
>  EXPORT_SYMBOL_GPL(init_pid_ns);
>  
> +struct pid dummy_pid = {
> +     .count          = ATOMIC_INIT(1),
> +     .numbers        = { {
> +             .nr             = 0,            /* this is what pid_nr will 
> return
> +                                              * for tasks with no pids
> +                                              */
> +             .ns             = &init_pid_ns,
> +     }, }
> +};
> +EXPORT_SYMBOL(dummy_pid);

Why is the EXPORT_SYMBOL() needed?
IOW, is some loadable module going to use this?

---
~Randy
-
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