Re: [patch 1/4] fs, proc: Introduce /proc/<pid>/task/<tid>/childrenentry v8

[Kees Cook]

On Mon, Jan 23, 2012 at 11:33 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:
> On Mon, Jan 23, 2012 at 10:54:53AM -0800, Kees Cook wrote:
>> On Mon, Jan 23, 2012 at 6:20 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxxx> wrote:
>> > When we do checkpoint of a task we need to know the list of children
>> > the task, has but there is no easy and fast way to generate reverse
>> > parent->children chain from arbitrary <pid> (while a parent pid is
>> > provided in "PPid" field of /proc/<pid>/status).
>> > [...]
>> > Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
>> > Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
>> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> > Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
>> > Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
>> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>>
>> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
>>
>> > +static int children_seq_show(struct seq_file *seq, void *v)
>> > +{
>> > +       struct inode *inode = seq->private;
>> > +       pid_t pid;
>> > +
>> > +       pid = pid_nr_ns(v, inode->i_sb->s_fs_info);
>> > +       return seq_printf(seq, " %d", pid);
>> > +}
>>
>> Does this mean the file contents always starts with a space? I think
>> I'd prefer a trailing space than a leading one. Better yet, neither.
>> :)
>>
>
> Yeah, it there children, they will be in say " 1 2 3 4\n" format.
> To drop this space completely i'll have to add more code, which I
> actually trying to escape. Can we live with it? ;)

How about just:

return seq_printf(seq, "%d ", pid);

instead?

-Kees

-- 
Kees Cook
ChromeOS Security
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