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SubjectRe: [PATCH -mm 3/4][AIO] - AIO completion signal notification
On Tue, 21 Nov 2006 17:02:28 -0800
Andrew Morton <akpm@osdl.org> wrote:

> On Mon, 20 Nov 2006 15:22:52 +0100
> S__bastien Dugu__ <sebastien.dugue@bull.net> wrote:
>
> > +static long aio_setup_sigevent(struct aio_notify *notify,
> > + struct sigevent __user *user_event)
> > +{
> > + sigevent_t event;
> > + struct task_struct *target;
> > +
> > + if (copy_from_user(&event, user_event, sizeof (event)))
> > + return -EFAULT;
> > +
> > + if (event.sigev_notify == SIGEV_NONE)
> > + return 0;
> > +
> > + notify->notify = event.sigev_notify;
> > + notify->signo = event.sigev_signo;
> > + notify->value = event.sigev_value;
> > +
> > + read_lock(&tasklist_lock);
> > + target = good_sigevent(&event);
> > +
> > + if (unlikely(!target || (target->flags & PF_EXITING)))
> > + goto out_unlock;
> > +
> > +
> > +
> > + if (notify->notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) {
> > + /*
> > + * This reference will be dropped in really_put_req() when
> > + * we're done with the request.
> > + */
> > + get_task_struct(target);
> > + }
>
> It worries me that this function can save away a task_struct* without
> having taken a reference against it.
>

OK. Does moving 'notify->target = target;' after the get_task_struct() will
do, or am I missing something more subtle?

Thanks,

Sébastien.
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