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SubjectRe: SCO: "thread creation is about a thousand times faster than on
On 27 Aug 2000, Linus Torvalds wrote:


>
> Btw, here's a simple thread-group patch. It doesn't actually _do_
> anything with the thread group part, but this is the kind of frame-work
> I've envisioned. Completely untested, of course, but with these kinds
> of security issues taken into account.
>
> Comments? At least it's small and simple..
>
> Linus



And what will be done, when thread-group leader (tgig==pid) will exec() ?
If I read your core correctly, it will be de_threaded by seting tgid=pid,
but it was before! So the process will _not_ be removed from thread group.
and it will remain in thread group _after_ exec.
Am I mistaken?


Martin





>
> ----
> diff -u --recursive --new-file penguin/linux/fs/exec.c linux/fs/exec.c
> --- penguin/linux/fs/exec.c Mon Aug 14 10:19:55 2000
> +++ linux/fs/exec.c Sun Aug 27 17:29:52 2000
> @@ -496,6 +496,25 @@
> write_unlock(&files->file_lock);
> }
>
> +/*
> + * An execve() will automatically "de-thread" the process.
> + * Note: we don't have to hold the tasklist_lock to test
> + * whether we migth need to do this. If we're not part of
> + * a thread group, there is no way we can become one
> + * dynamically. And if we are, we only need to protect the
> + * unlink - even if we race with the last other thread exit,
> + * at worst the list_del_init() might end up being a no-op.
> + */
> +static inline void de_thread(struct task_struct *tsk)
> +{
> + if (!list_empty(&tsk->thread_group)) {
> + write_lock_irq(&tasklist_lock);
> + list_del_init(&tsk->thread_group);
> + write_unlock_irq(&tasklist_lock);
> + }
> + tsk->tgid = tsk->pid;
> +}
> +
> int flush_old_exec(struct linux_binprm * bprm)
> {
> char * name;
> @@ -533,6 +552,8 @@
> current->comm[i] = '\0';
>
> flush_thread();
> +
> + de_thread(current);
>
> if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||


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Martin "MaD" Douda
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