Re: [PATCH 11/12] pid: rewrite task helper functions avoiding task->pid and task->tgid

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.

> 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().

> > > > 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".

Oleg.