>>> On 04.12.12 at 19:21, Olaf Hering <o...@aepfle.de> wrote: > On Tue, Dec 04, Jan Beulich wrote: > >> This looks necessary but insufficient - there's nothing really >> preventing backend_changed() from being called more than once >> for a given device (is simply the handler of xenbus watch). Hence >> I think either that function needs to be guarded against multiple >> execution (e.g. by removing the watch from that function itself, >> if that's permitted by xenbus), or to properly deal with the >> effects this has (including but probably not limited to the leaking >> of be->mode). > > If another watch does really trigger after the kfree(be) in > xen_blkbk_remove(), wouldnt backend_changed access stale memory? > So if that can really happen in practice, shouldnt the backend_watch be > a separate allocation instead being contained within backend_info? > > Looking at unregister_xenbus_watch, it clears removes the watch from the > list, so that process_msg will not see it anymore.
That's not the scenario I was talking about: I'm concerned about multiple calls to backend_changed() to similarly leak "mode" (and possibly cause other bad stuff to happen) while the device is still alive - after all it overwrites "mode" without checking what's in there. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
