On Wed, Apr 23, 2008 at 03:36:19PM +0200, Andrea Arcangeli wrote: > On Tue, Apr 22, 2008 at 06:07:27PM -0500, Robin Holt wrote: > > > The only other change I did has been to move mmu_notifier_unregister > > > at the end of the patchset after getting more questions about its > > > reliability and I documented a bit the rmmod requirements for > > > ->release. we'll think later if it makes sense to add it, nobody's > > > using it anyway. > > > > XPMEM is using it. GRU will be as well (probably already does). > > XPMEM requires more patches anyway. Note that in previous email you > told me you weren't using it. I think GRU can work fine on 2.6.26
I said I could test without it. It is needed for the final version. It also makes the API consistent. What you are proposing is equivalent to having a file you can open but never close. This whole discussion seems ludicrous. You could refactor the code to get the sorted list of locks, pass that list into mm_lock to do the locking, do the register/unregister, then pass the same list into mm_unlock. If the allocation fails, you could fall back to the older slower method of repeatedly scanning the lists and acquiring locks in ascending order. > without mmu_notifier_unregister, like KVM too. You've simply to unpin > the module count in ->release. The most important bit is that you've > to do that anyway in case mmu_notifier_unregister fails (and it can If you are not going to provide the _unregister callout you need to change the API so I can scan the list of notifiers to see if my structures are already registered. We register our notifier structure at device open time. If we receive a _release callout, we mark our structure as unregistered. At device close time, if we have not been unregistered, we call _unregister. If you take away _unregister, I have an xpmem kernel structure in use _AFTER_ the device is closed with no indication that the process is using it. In that case, I need to get an extra reference to the module in my device open method and hold that reference until the _release callout. Additionally, if the users program reopens the device, I need to scan the mmu_notifiers list to see if this tasks notifier is already registered. I view _unregister as essential. Did I miss something? Thanks, Robin ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
