netdev - Re: Compiler warning

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Date:   Mon, 4 Feb 2019 18:55:19 -0800
From:   David Ahern <dsahern@...il.com>
To:     Koen Vandeputte <koen.vandeputte@...ntric.com>,
        netdev@...r.kernel.org
Subject: Re: Compiler warning

On 2/4/19 3:43 AM, Koen Vandeputte wrote:
> Hi All,
> 
> I'm seeing following compiler warning during kernel compilation
> (5.0-rc5  and  4.14.96):
> 
> 
> net/core/dev.c: In function 'validate_xmit_skb_list':
> net/core/dev.c:3405:15: warning: 'tail' may be used uninitialized in
> this function [-Wmaybe-uninitialized]
>     tail->next = skb;
>     ~~~~~~~~~~~^~~~~
> 
> 
> Source shows this:
> 
> https://elixir.bootlin.com/linux/v5.0-rc5/source/net/core/dev.c#L3387
> 
> Looks like "tail" can get deferenced while it indeed doesn't get
> initialized? Kind regards, Koen
> 

same with this one - false positive. head is initialized to NULL. tail
is set on the first pass through the loop.

What compiler / version is this?