[Devel] Re: [PATCH 16/28] [FLAT 1/6] Changes in data structures for flat model

[Pavel Emelianov]

Eric W. Biederman wrote:
> Pavel Emelianov <xemul at openvz.org> writes:
> 

[snip]

>>> | --- ./include/linux/sched.h.flatdatast 2007-06-15 15:14:33.000000000 +0400
>>> | +++ ./include/linux/sched.h	2007-06-15 15:19:14.000000000 +0400
>>> | @@ -482,7 +482,10 @@ struct signal_struct {
>>> |  		pid_t session __deprecated;
>>> |  		pid_t __session;
>>> |  	};
>>> | -
>>> | +#ifdef CONFIG_PID_NS_FLAT
>>> | +	pid_t vpgrp;
>>> | +	pid_t vsession;
>>> | +#endif
>>> |  	/* boolean value for session group leader */
>>> |  	int leader;
>>> | 
>>> | @@ -944,6 +947,11 @@ struct task_struct {
>>> |  	unsigned did_exec:1;
>>> |  	pid_t pid;
>>> |  	pid_t tgid;
>>> | +#ifdef CONFIG_PID_NS_FLAT
>>> | +	/* hash the virtual ids as well */
>>> | +	pid_t vpid;
>>> | +	pid_t vtgid;
>>> | +#endif
> 
> Adding vpgrp, vsession, vpid, and vtgid is wrong.
> 
> A case can probably be made for caching the common case (users view),
> but we already have fields for that.
> 
> For a global view we must use struct pid *, otherwise we are just asking
> for trouble.

Nope. If we have global unique numerical pid we're not asking for
trouble. We're just making kernel work like it always did. Virtual
pid makes sense *only* when interacting with user level.

Making task->pid virtual is asking for trouble.

> Eric

Pavel
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