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Re: [PATCH] (2/4) packet scheduler bad TDIFF_SAFE in csz

To: "David S. Miller" <davem@xxxxxxxxxx>
Subject: Re: [PATCH] (2/4) packet scheduler bad TDIFF_SAFE in csz
From: jamal <hadi@xxxxxxxxxx>
Date: 29 Jun 2004 18:22:37 -0400
Cc: Stephen Hemminger <shemminger@xxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <20040629144506.0649d217.davem@xxxxxxxxxx>
Organization: jamalopolis
References: <20040629140016.4afeb36b@xxxxxxxxxxxxxxxxxxxxx> <20040629144506.0649d217.davem@xxxxxxxxxx>
Reply-to: hadi@xxxxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
That scheduler is only a relic.
Nobody uses it ;-> Check the cofig help.
Pretty sure if you study it youll find a lot more bugs.

cheers,
jamal

On Tue, 2004-06-29 at 17:45, David S. Miller wrote:
> On Tue, 29 Jun 2004 14:00:16 -0700
> Stephen Hemminger <shemminger@xxxxxxxx> wrote:
> 
> > This code in the csz scheduler, is just plain broken.  The TDIFF_SAFE 
> > effectively expands to:
> >     unsigned long delay = now - q->t_c;
> >     if (delay > 0) {
> >             delay = 0;
> >             goto do_reset;
> >     }
> >     if (delay >> q->delta_log)
> > 
> > So delay is always 0!  I assume that what was originally intended
> > is the to keep delay bounded to 1<<q->delta_log. 
> 
> This bug has been there since day one, wow.
> 
> Good spotting, applied.
> 
> 


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