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SubjectRe: [PATCH -mm 3/5][AIO] - export good_sigevent()
On Wed, 29 Nov 2006 14:54:25 +0000, Christoph Hellwig <hch@infradead.org> wrote:

> > +/***
> > + * good_sigevent - check and get target task from a sigevent.
> > + * @event: the sigevent to be checked
> > + *
> > + * This function must be called with tasklist_lock held for reading.
> > + */
> > +struct task_struct * good_sigevent(sigevent_t * event)
> > +{
> > + struct task_struct *rtn = current->group_leader;
> > +
> > + if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
> > + (!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
> > + rtn->tgid != current->tgid ||
> > + (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
> > + return NULL;
> > +
> > + if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
> > + ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
> > + return NULL;
> > +
> > + return rtn;
> > +}
>
> And while we're at it we should badly beat up the person that wrote this
> mess in the first time.

Agreed.

> To be somewhat readable it should look like:
>
> static struct task_struct *good_sigevent(sigevent_t *event)
> {
> struct task_struct *task = current->group_leader;
>
> if ((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
> if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
> return NULL;
> }
>
> if (event->sigev_notify & SIGEV_THREAD_ID) {
> if ((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL)
> return NULL;
> task = find_task_by_pid(event->sigev_notify_thread_id);
> if (!task || task->tgid != current->tgid)
> return NULL;
> }
>
> return task;
> }

Yes, will incorporate this.

>
> And btw, looking at its currentl caller I see why we need the PF_EXITING
> flag I recommended to remove easiler on, it even has a big comment that
> we should copy & paste to aio.c aswell.

Well, I do not take the siglock anymore, so I don't think the comment
really applies here.

> Still no idea why it's doing
> the selectiv reference grabbing, though.
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