[Devel] [RFC][PATCH 06/16] Define is_global_init()

[Pavel Emelianov]

sukadev at us.ibm.com wrote:
> Pavel Emelianov [xemul at sw.ru] wrote:
> | > Index: lx26-21-mm2/kernel/pid.c
> | > ===================================================================
> | > --- lx26-21-mm2.orig/kernel/pid.c	2007-05-22 16:59:34.000000000 -0700
> | > +++ lx26-21-mm2/kernel/pid.c	2007-05-22 16:59:46.000000000 -0700
> | > @@ -71,6 +71,27 @@ struct pid_namespace init_pid_ns = {
> | >  	.child_reaper = &init_task
> | >  };
> | >  
> | > +
> | > +/**
> | > + * is_global_init - check if a task structure is init
> | > + * @tsk: Task structure to be checked.
> | > + *
> | > + * Check if a task structure is the first user space task the kernel created.
> | > + */
> | > +int is_global_init(struct task_struct *tsk)
> | > +{
> | > +	return (task_active_pid_ns(tsk) == &init_pid_ns && tsk->pid == 1);
> | 
> | This can OOPS if you pass arbitrary task to this call...
> | tsk->nsproxy can already be NULL.
> 
> Hmm. You are right. btw, this could be a bisect issue. Patch 9 of uses
> pid_ns from pid->upid_list and removes nsproxy->pid_ns.

Yes, but that patch is not good either.
task_pid(tsk) may become NULL as well and this will oops.

> | 
> | > +}
> | > +
> | > +/*
> | > + * is_container_init:
> | > + * check whether in the task is init in it's own pid namespace.
> | > + */
> | > +int is_container_init(struct task_struct *tsk)
> | > +{
> | > +	return tsk->pid == 1;
> | > +}
> | > +
> | >  /*
> | >   * Note: disable interrupts while the pidmap_lock is held as an
> | >   * interrupt might come in and do read_lock(&tasklist_lock).
> | > _______________________________________________
> | > Containers mailing list
> | > Containers at lists.linux-foundation.org
> | > https://lists.linux-foundation.org/mailman/listinfo/containers
> | > 
> | > _______________________________________________
> | > Devel mailing list
> | > Devel at openvz.org
> | > https://openvz.org/mailman/listinfo/devel
> | > 
> 

_______________________________________________
Containers mailing list
Containers at lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers