Compiler warning

Compiler warning

[Koen Vandeputte]

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

Re: Compiler warning

[David Ahern]

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?

Re: Compiler warning

[Koen Vandeputte]

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

compiler warning

[Matthias Fuchs]

Hi,

I do not understand this compiler warning:

/tmp/ccu149sf.s: Assembler messages:
/tmp/ccu149sf.s:5: Warning: Ignoring changed section attributes for
.modinfo

It appears everytime, when I use the ppc_4xx-gcc from MontaVista.
What does it mean ? Do I have to take care aboutit ?

Matthias

--
-------------------------------------------------
\ Matthias Fuchs                                 \
 \ esd electronic system design Gmbh              \
  \ Vahrenwalder Straße 205                        \
   \ D-30165 Hannover                               \
    \ email: matthias.fuchs@esd-electronics.com      \
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Re: compiler warning

[Cal Erickson]

Matthias,
This is a warning that the attributes for a section which
the linker creates when the link is done has had its
initial attributes changed. We at MontaVista have seen
this and we will be posting a fix with our HHL 2.0 release.
It is only a warning and will not affect the executable code.

Cal
Matthias Fuchs wrote:

> Hi,
>
> I do not understand this compiler warning:
>
> /tmp/ccu149sf.s: Assembler messages:
> /tmp/ccu149sf.s:5: Warning: Ignoring changed section attributes for
> .modinfo
>
> It appears everytime, when I use the ppc_4xx-gcc from MontaVista.
> What does it mean ? Do I have to take care aboutit ?
>
> Matthias
>
> --
> -------------------------------------------------
> \ Matthias Fuchs                                 \
>  \ esd electronic system design Gmbh              \
>   \ Vahrenwalder Straße 205                        \
>    \ D-30165 Hannover                               \
>     \ email: matthias.fuchs@esd-electronics.com      \
>      \ phone: +49-511-37298-0                         \
>       \ fax:   +49-511-37298-68                        \
>        --------------------------------------------------
>

--
===========================================================================
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Phone (408) 328-0304         Sunnyvale CA 94085
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