On Tue, Jul 23, 2002 at 04:56:32PM +0200, Trond Myklebust wrote:
> I disagree. As it stands, NLM_NEVER == (~(unsigned long)0), and "when"
> is unsigned long, so the only thing we need to protect against is if
> we hit the 'magic value' NLM_NEVER. Note that the time_before_eq()
> comparison ensures that we cope well with jiffy wraparound etc, so the
> entry should *not* in fact get put at the end of the list as you
> claimed.
>
> With the above change (plus your change to set NLM_NEVER=0x7fffffff),
> we end up never retrying locks that just happen to have been put on
> the list at a time when the value of 'jiffies' happens to be > 0x7fffffff.
But as it is today, all blocked locks get inserted at the end of the
list because time_before_eq does a signed comparison! With the unpatched
code, when you have a blocked lock, and the conflicting lock is removed,
lockd will never send out a GRANTED_MSG. Because the blocked lock is at the
end of the list, and never picked up.
That's the real reason for changing NLM_NEVER to the largest _signed_
quantity. And if you do that, you need to deal with jiffy wraparound.
Maybe the way I did it is not optiomal, I concede. But you can't leave
it at ~0UL.
> Patrice Dumas recently did some work on implementing this both for
> NLMv1,2,3 and NLM4, so I was planning on integrating his changes into
> 2.4.20.
As you can see from the patch, it's not really much you need to add.
The functionality is all there, one only needs to decode the GRANTED_RES
call rather than dropping it.
Olaf
-- Olaf Kirch | Anyone who has had to work with X.509 has probably okir@suse.de | experienced what can best be described as ---------------+ ISO water torture. -- Peter Gutmann - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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