Messages in this thread |  | | Date | Fri, 3 Jul 2015 09:02:51 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH 6/6] Fix unsafe fw_event_list usage |
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On Mon, Jun 08, 2015 at 08:50:56PM -0700, Calvin Owens wrote: > Since the fw_event deletes itself from the list, cleanup_queue() can > walk onto garbage pointers or walk off into freed memory. > > This refactors the code in _scsih_fw_event_cleanup_queue() to not > iterate over the fw_event_list without a lock.
I think this really should be folded into the previous one, with the fixes in this one the other refcounting change don't make a whole lot sense.
> +static struct fw_event_work *dequeue_next_fw_event(struct MPT2SAS_ADAPTER *ioc) > +{ > + unsigned long flags; > + struct fw_event_work *fw_event = NULL; > + > + spin_lock_irqsave(&ioc->fw_event_lock, flags); > + if (!list_empty(&ioc->fw_event_list)) { > + fw_event = list_first_entry(&ioc->fw_event_list, > + struct fw_event_work, list); > + list_del_init(&fw_event->list); > + fw_event_work_get(fw_event); > + } > + spin_unlock_irqrestore(&ioc->fw_event_lock, flags); > + > + return fw_event;
Shouldn't we have a reference for each item on the list that gets transfer to whomever removes it from the list?
Additionally _firmware_event_work should call dequeue_next_fw_event first in the function so that item is off the list before we process it, and can then just drop the reference once it's done.
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