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SubjectRe: [PATCH 09/23] ns: Introduce ns_idr to be able to iterate all allocated namespaces in the system
On Thu, Jul 30, 2020 at 05:12:09PM +0300, Kirill Tkhai wrote:
> On 30.07.2020 16:56, Matthew Wilcox wrote:
> > On Thu, Jul 30, 2020 at 04:32:22PM +0300, Kirill Tkhai wrote:
> >> On 30.07.2020 15:23, Matthew Wilcox wrote:
> >>> xa_erase_irqsave();
> >>
> >> static inline void *xa_erase_irqsave(struct xarray *xa, unsigned long index)
> >> {
> >> unsigned long flags;
> >> void *entry;
> >>
> >> xa_lock_irqsave(xa, flags);
> >> entry = __xa_erase(xa, index);
> >> xa_unlock_irqrestore(xa, flags);
> >>
> >> return entry;
> >> }
> >
> > was there a question here?
>
> No, I just I will add this in separate patch.

Ah, yes. Thanks!

> >>>> +struct ns_common *ns_get_next(unsigned int *id)
> >>>> +{
> >>>> + struct ns_common *ns;
> >>>> +
> >>>> + if (*id < PROC_NS_MIN_INO - 1)
> >>>> + *id = PROC_NS_MIN_INO - 1;
> >>>> +
> >>>> + *id += 1;
> >>>> + *id -= PROC_NS_MIN_INO;
> >>>> +
> >>>> + rcu_read_lock();
> >>>> + do {
> >>>> + ns = idr_get_next(&ns_idr, id);
> >>>> + if (!ns)
> >>>> + break;
> >>>
> >>> xa_find_after();
> >>>
> >>> You'll want a temporary unsigned long to work with ...
> >>>
> >>>> + if (!refcount_inc_not_zero(&ns->count)) {
> >>>> + ns = NULL;
> >>>> + *id += 1;
> >>>
> >>> you won't need this increment.
> >>
> >> Why? I don't see a way xarray allows to avoid this.
> >
> > It's embedded in xa_find_after().
>
> How is it embedded to check ns->count that it knows nothing?

I meant you won't need to increment '*id'. The refcount is, of course,
your business.

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