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Date: Mon, 16 Jan 2012 20:20:21 +0400 From: Cyrill Gorcunov <gorcunov@...il.com> To: Oleg Nesterov <oleg@...hat.com> Cc: LKML <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Pavel Emelyanov <xemul@...allels.com>, Serge Hallyn <serge.hallyn@...onical.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Tejun Heo <tj@...nel.org>, Andrew Vagin <avagin@...nvz.org>, Vasiliy Kulikov <segoon@...nwall.com> Subject: Re: [RFC] fs, proc: Introduce /proc/<pid>/task/<tid>/children entry v6 On Mon, Jan 16, 2012 at 05:11:14PM +0100, Oleg Nesterov wrote: > On 01/16, Cyrill Gorcunov wrote: > > > > +get_children_pid(struct proc_pid_children_iter *iter, struct pid *pid_prev, loff_t pos) > > +{ > > + struct task_struct *start, *task; > > + struct pid *pid = NULL; > > + > > + read_lock(&tasklist_lock); > > + > > + start = pid_task(iter->pid_start, PIDTYPE_PID); > > + if (!start) > > + goto out; > > + > > + /* > > + * Lets try to continue searching first, this gives > > + * us significant speedup on children-rich processes. > > + */ > > + if (pid_prev) { > > + task = pid_task(pid_prev, PIDTYPE_PID); > > + if (task && task->real_parent == start && > > + !(list_empty(&task->sibling))) { > > Damn. No, this is wrong. > > Damn! Yes, it was we who told you to check list_empty(sibling) ;) > > But this is not enough. exit_ptrace() can do list_move() without > changing ->real_parent. > > I'll try to think. At first glance we can rely on EXIT_DEAD, but > I'd like to avoid this, I think EXIT_DEAD should die. > Ouch! Thanks for catching this Oleg. I'll try to come with something to show as well. Cyrill -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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