[Devel] Re: [PATCH 2/13] Small preparations for namespaces

[Pavel Emelianov]

Serge E. Hallyn wrote:
> Quoting Pavel Emelianov (xemul at openvz.org):
>> This includes #ifdefs in get/put_pid_ns and rewriting
>> the child_reaper() function to the more logical view.
>>
>> This doesn't fit logically into any other patch so
>> I decided to make it separate.
>>
>> Signed-off-by: Pavel Emelianov <xemul at openvz.org>
>>
>> ---
>>
>> diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
>> index 169c6c2..7af7191 100644
>> --- a/include/linux/pid_namespace.h
>> +++ b/include/linux/pid_namespace.h
>> @@ -26,7 +26,9 @@ extern struct pid_namespace init_pid_ns;
>>
>>  static inline void get_pid_ns(struct pid_namespace *ns)
>>  {
>> +#ifdef CONFIG_PID_NS
>>  	kref_get(&ns->kref);
>> +#endif
>>  }
>>
>>  extern struct pid_namespace *copy_pid_ns(int flags, struct pid_namespace *ns);
>> @@ -34,12 +36,15 @@ extern void free_pid_ns(struct kref *kre
>>
>>  static inline void put_pid_ns(struct pid_namespace *ns)
>>  {
>> +#ifdef CONFIG_PID_NS
>>  	kref_put(&ns->kref, free_pid_ns);
>> +#endif
>>  }
>>
>>  static inline struct task_struct *child_reaper(struct task_struct *tsk)
>>  {
>> -	return init_pid_ns.child_reaper;
>> +	BUG_ON(tsk != current);
>> +	return tsk->nsproxy->pid_ns->child_reaper;
>>  }
>>
>>  #endif /* _LINUX_PID_NS_H */
> 
> This can't be bisect-safe, right?  You can't just use
> tsk->nsproxy->pid_ns, as you've pointed out yourself.

I can :) See - I have a proving BUG_ON() here.

> 
> -serge
>