Re: [PATCH 1/9] exec: add a global execve counter

From: Oleg Nesterov
Date: Mon Mar 12 2012 - 11:19:22 EST


On 03/12, Djalal Harouni wrote:
>
> On Sun, Mar 11, 2012 at 06:25:12PM +0100, Oleg Nesterov wrote:
> >
> > Well, I don't think it is right to add this counter into task_struct.
> >
> > It should be per-process, signal_struct makes more sense. Or may be
> > mm_struct.
> Some /proc/<pid>/{syscall,stack,...} do not operate on mm_struct so why we
> should add the: "acquire a reference to mm, get exec_id and mmput".

This could be simpler, just read the counter under task_lock(). And
unless I misread the next patches syscall/stack can use current->mm
lockless.

OK, nevermind.

> For the signal_struct currently I don't know, from a comment it seems that
> signal_struct can be shared!

Yes, it is shared, and that is why it makes sense for the per-process
data. All threads in the thread group (process) have the same ->signal.
And unlike ->mm, ->signal survives after exec.

Oleg.

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