Date: Tue, 20 Nov 2012 10:09:58 -0800
From: Stephen Hemminger <shemminger@vyatta.com>
To: David Miller <davem@davemloft.net>
Cc: paolo.valente@unimore.it, jhs@mojatatu.com, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, rizzo@iet.unipi.it, fchecconi@gmail.com
Subject: Re: [PATCH] pkt_sched: QFQ Plus: fair-queueing service at DRR cost
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On Tue, 20 Nov 2012 13:02:02 -0500 (EST)
David Miller <davem@davemloft.net> wrote:

> From: Stephen Hemminger <shemminger@vyatta.com>
> Date: Tue, 20 Nov 2012 09:53:04 -0800
> 
> > There are actually lots of bogus warnings than seem to only occur
> > because gcc 4.4 does a bad job of checking. Later versions are fixed
> > and don't generate warnings.
> > 
> > My preference is to not add the unnecessary initialization because
> > if you get in the habit of doing it. The whole purpose of the uninitialized
> > check is lost. 
> 
> Try again, this was with gcc-4.7.2-2 on Fedora.
> 
> There are too many preconditions, across multiple basic block, which
> together ensure the skb is in fact initialized at the point in
> question and the compiler simply isn't sophisticated enough to see
> that.

Weird, it compiles  clean on x86-84 on Debian.
gcc-4.7.real (Debian 4.7.2-4) 4.7.2
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