Re: [rfc] "fair" rw spinlocks

[Paul E. McKenney]

On Mon, Nov 30, 2009 at 06:13:33PM +0100, Nick Piggin wrote:
> On Mon, Nov 30, 2009 at 09:05:57AM -0800, Linus Torvalds wrote:
> Secondly:
> 
> > 	static void tasklist_read_lock(void)
> > 	{
> > 		preempt_disable();
> > 		if (!current->tasklist_count++)
> 
> What happens if an interrupt and nested tasklist_read_lock() happens
> here?

Ouch!!!  This race affects the reader-writer-lock version as well.
Ah well, looks like interrupt disabling is required either way.

							Thanx, Paul
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