lkml.org 
[lkml]   [2011]   [Dec]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [rfc 2/3] fs, proc: Introduce the Children: line in /proc/<pid>/status
On Thu, 1 Dec 2011 13:54:34 +0400
Cyrill Gorcunov <gorcunov@gmail.com> wrote:

> +int proc_pid_children(struct seq_file *m, struct pid_namespace *ns,
> + struct pid *pid, struct task_struct *task)
> +{
> + struct task_struct *c;
> +
> + read_lock(&tasklist_lock);
> + list_for_each_entry(c, &task->children, sibling)
> + seq_printf(m, " %d", pid_nr_ns(task_pid(c), ns));
> + read_unlock(&tasklist_lock);
> + seq_putc(m, '\n');
> +
> + return 0;
> +}

That's a potentially very long hold time for tasklist_lock, and
userspace can invoke this at a high frequency. Not good.

I think this can all be done under rcu_read_lock() with
list_for_each_entry_rcu().



\
 
 \ /
  Last update: 2011-12-01 22:31    [W:0.111 / U:0.776 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site