Re: [PATCH 4/4] pidns: Use task_active_pid_ns where appropriate

[Daniel Lezcano]

On 01/31/2011 12:26 PM, Alexey Dobriyan wrote:
> On Mon, Jan 31, 2011 at 12:25 PM, Daniel Lezcano<daniel.lezcano@xxxxxxx>  wrote:
> > The expressions tsk->nsproxy->pid_ns and task_active_pid_ns
> > aka ns_of_pid(task_pid(tsk)) should have the same number of
> > cache line misses with the practical difference that
> > ns_of_pid(task_pid(tsk)) is released later in a processes life.
> >
> > Furthermore by using task_active_pid_ns it becomes trivial
> > to write an unshare implementation for the the pid namespace.
> >
> > So I have used task_active_pid_ns everywhere I can.
> Yet current->nsproxy->pid_ns is way clearer.
> Because live current always has pid_ns.
>
> This task_active_pid_ns() is misnamed(?) because it does matter only
> for dead tasks?

Actually this function is later used, for the unshare, to get the pid_ns 
of a specific task, not the current one.

http://kerneltrap.org/mailarchive/linux-kernel/2010/6/20/4585095

Do you suggest task_pid_ns(struct task_struct *tsk) would be a better name ?

> > -               current->nsproxy->pid_ns->last_pid);
> > +               task_active_pid_ns(current)->last_pid);
> I thought of doing exactly opposite patch :-)

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