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 > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
