netdev - Re: [NET]: gen_estimator deadlock fix

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Date:	Mon, 16 Jul 2007 20:45:05 +0300
From:	Ranko Zivojnovic <ranko@...dernet.net>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	Jarek Poplawski <jarkao2@...pl>, netdev@...r.kernel.org
Subject: Re: [NET]: gen_estimator deadlock fix

Patrick McHardy wrote:
> Jarek Poplawski wrote:
> > There is probably quite easy way to get rid of this one race only
> > by e.g. replacing *bstats field with NULL in gen_kill_estimator,
> > and check for this in est_timer just after taking a lock.
> > 
You are absolutely right - I definitely overcomplicated the solution to
the actual problem in hand - the deadlock... Attached is the patch that
does exactly as above and should put a final resolution to the current
gen_estimator issues ... I've also given it a spin and so far it looks
ok. I will re-post it tomorrow evening for inclusion in the tree if no
objections come in the mean time.

> Jarek Poplawski wrote:
> > The gain from an api change would be mainly faster gen_kill_
> > and gen_replace_estimator. But, on the other hand, you have it
> > almost done. Ranko, I think these changes need opinion of more
> > maintainers as soon as possible - after all they could have some
> > objections; IMHO at least: Jamal Hadi Salim, Thomas Graf (authors
> > plus act_), Stephen Hemminger (sch_netem) and Jiri Benc
> > (net/mac80211).

>>From my point of view the api change would help in untying the knot
entirely... It would become an independent piece of code with a sole
focus on the rate estimation. I am even thinking of making it even more
independent than the previous patch I posted... A pure small library
that can be configured to track rates with configurable algo's etc... It
may prove to be useful for the other things as well. 

But now that gen_estimator issues are hopefully resolved through this
simpler patch - the api change can take its own pace.

Patrick McHardy wrote:
> Frankly, all we need is a final patch.

The patch that resolves the ABBA deadlock is attached. WRT api patch -
although I did not face any problems so far, I still need to do more
comprehensive testing...

Best regards and thanks for the patience,

R.



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