Re: [rfc] "fair" rw spinlocks

Nick Piggin
2009-11-25T08:56:06Z

On Wed, Nov 25, 2009 at 09:49:23AM +0100, Andi Kleen wrote:
> David Miller <davem@davemloft.net> writes:
> >
> > I think nobody would notice if you changed tasklist_lock into
> > a spinlock_t, and this would solve the DoS because at least on
> > x86 you'd end up with the ticket spinlocks.
>
> iirc tasklist_lock was one of them who could be potentially nested.
>
> So just turning it into a spinlock might deadlock.

It can be nested I think due to interrupt context. But if the read
side disables interrupts too, then I think it should be OK (though
I haven't audited this closely).