netdev - Re: -Wsometimes-uninitialized Clang warning in net/tipc/node.c

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Date:   Wed, 20 Mar 2019 12:07:52 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Jon Maloy <jon.maloy@...csson.com>,
        Ying Xue <ying.xue@...driver.com>,
        "David S. Miller" <davem@...emloft.net>,
        tipc-discussion@...ts.sourceforge.net
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com
Subject: Re: -Wsometimes-uninitialized Clang warning in net/tipc/node.c

On Thu, Mar 07, 2019 at 05:17:23PM -0700, Nathan Chancellor wrote:
> Hi all,
> 
> We are trying to get Clang's -Wsometimes-uninitialized turned on for the
> kernel as it can catch some bugs that GCC can't. This warning came up:
> 
> net/tipc/node.c:831:6: warning: variable 'maddr' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>         if (!tipc_link_is_establishing(l)) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> net/tipc/node.c:847:46: note: uninitialized use occurs here
>         tipc_bearer_xmit(n->net, bearer_id, &xmitq, maddr);
>                                                     ^~~~~
> net/tipc/node.c:831:2: note: remove the 'if' if its condition is always true
>         if (!tipc_link_is_establishing(l)) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> net/tipc/node.c:821:31: note: initialize the variable 'maddr' to silence this warning
>         struct tipc_media_addr *maddr;
>                                      ^
>                                       = NULL
> 1 warning generated.
> 
> This definitely appears to be a legitimate warning but I'm not sure of
> the proper solution (should maddr be initialized to NULL or should it be
> set to something different in the else branch). Your input would be
> greatly appreciated.
> 
> Cheers,
> Nathan

Gentle ping (if there was a response to this, I didn't receive it). I
know I sent it in the middle of a merge window so I get if it slipped
through the cracks.

Thanks,
Nathan