Messages in this thread | | | Date | Mon, 30 Nov 2009 08:20:58 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [rfc] "fair" rw spinlocks |
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On Mon, Nov 30, 2009 at 08:55:57AM +0100, Nick Piggin wrote: > On Sat, Nov 28, 2009 at 09:30:18AM -0800, Linus Torvalds wrote: > > So as far as I can tell, we have only one real user of rwlocks where > > livelocks might be relevant, but that one real user absolutely _requires_ > > the unfair behavior. > > Yes, although the behaviour required is that it can be recursively > acquired. So we could still have a lock that disallows new non recursive > read acquires when there is a pending write locker. > > RCU seems nicer, but tasklist lock locking scares me so I wanted to fix > it the easy way :)
Having a livelock-free tasklist lock would certainly make it easier to apply things like RCU on a code-path-by-code-path basis as needed. Much less scary than a big-bang rip-and-replace.
Thanx, Paul
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