On (09/09/13 17:52), Dan Carpenter wrote:
> On Mon, Sep 09, 2013 at 05:42:59PM +0300, Sergey Senozhatsky wrote:
> > > 3) Explain why it is safe to test zram->slot_free_rq when we are not
> > > holding the lock. I think it is unsafe. I don't want to even think
> > > about it without the numbers.
> >
> > atomic pointer test, which is either NULL or !NULL.
> >
>
> That's not how concurency works. Atomic types are complicated than
> that. Anyway, the zram maintainers don't need me to explain that to
> them so I'll let them take over from here.
>
yes, I understand that. but can't we check slot_free_rq pointer
(32 or 64 bit read) w/o locking to just decide if we must:
-- call handle_pending_slot_free()
-- take the slot_free_lock
-- check slot_free_rq again (this time under the slot_free_lock) and perform
slot_free_rq operations while it is !NULL.
-ss
> regards,
> dan carpenter
>
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