netdev - Re: Compiler warning

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Message-ID: <ec477cd9-0bd2-25c5-70c3-c3b7187446b3@ncentric.com>
Date:   Thu, 7 Feb 2019 14:55:10 +0100
From:   Koen Vandeputte <koen.vandeputte@...ntric.com>
To:     David Ahern <dsahern@...il.com>, netdev@...r.kernel.org
Subject: Re: Compiler warning


On 05.02.19 03:55, David Ahern wrote:
> 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?

Thanks for confirming David. (for both of the warnings)
This is seen using GCC 7.4.0

I don't know the policy upstream regarding compiler warnings .. so 
thought I should report these. :)

Regards,

Koen