Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 16 Dec 2013 17:20:51 -0500 | From | Richard Guy Briggs <> | Subject | Re: [PATCH 11/12] pid: rewrite task helper functions avoiding task->pid and task->tgid |
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On 13/12/16, Oleg Nesterov wrote: > Hi Richard, > > Sorry, I already forgot the context, not sure I understand your email > correctly. > > On 12/16, Richard Guy Briggs wrote: > > On 13/08/26, Richard Guy Briggs wrote: > > > On Thu, Aug 22, 2013 at 09:08:48PM +0200, Oleg Nesterov wrote: > > > > On 08/20, Richard Guy Briggs wrote: > > > > > > > > > > static inline int is_global_init(struct task_struct *tsk) > > > > > { > > > > > - return tsk->pid == 1; > > > > > + return task_pid_nr(tsk) == 1; > > > > > } > > > > > > > > Probably it would be better to simply kill it. Almost every usage is > > > > wrong. > > > > > > Can you be more clear? I don't follow. It should instead return a > > > boolean. Usage of is_global_init() or task_pid_nr()? > > > > > > If is_global_init(), is that because they could be unaware of pid > > > namespaces? > > > > > > If task_pid_nr(), is that for the same reason? > > > > Oleg, I still don't understand your comment above. Kill what, > > "is_global_init()"? If so, how is almost every usage of it wrong? > > Because is_global_init() is only true for the main thread of /sbin/init. > > Just look at oom_unkillable_task(). It tries to not kill init. But, say, > select_bad_process() can happily find a sub-thread of is_global_init() > and still kill it.
Ah! So it should be task_tgid_nr(tsk) == 1.
> > There are a number of functions that call is_global_init(). Might any > > of them be called from inside the namespace context of a container and > > hence should return true? > > Not sure I understand, but certainly some callers should check ->child_reaper > or SIGNAL_UNKILLABLE instead. Say, unhandled_signal().
So in some situations it should allow it to kill init of a container and in others, refuse it.
> > > > > static inline bool is_idle_task(const struct task_struct *p) > > > > > { > > > > > - return p->pid == 0; > > > > > + return task_pid(p) == &init_struct_pid; > > > > > } > > > > > > > > hmm. there should be a simpler check for this... > > > > > > Other than the original, this one is pretty simple. What did you have > > > in mind? > > > > I vaguely remember a clarification to this, but don't remember and can't > > find it. What sort of simplification did you have in mind? > > I do not remember ;) Most probably, I meant "it would be nice to find a > simpler check".
I'll stick with task_pid_nr(p) == 0.
> Oleg.
- RGB
-- Richard Guy Briggs <rbriggs@redhat.com> Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat Remote, Ottawa, Canada Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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