netdev - Re: [bpf-next 3/3] samples/bpf: fix uninitialized warning with test_current_task_under

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Date:   Sat, 17 Dec 2022 09:49:31 -0800
From:   Yonghong Song <yhs@...a.com>
To:     "Daniel T. Lee" <danieltimlee@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Yonghong Song <yhs@...com>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [bpf-next 3/3] samples/bpf: fix uninitialized warning with
 test_current_task_under_cgroup



On 12/17/22 7:38 AM, Daniel T. Lee wrote:
> Currently, compiling samples/bpf with LLVM warns about the uninitialized
> use of variable with test_current_task_under_cgroup.
> 
>      ./samples/bpf/test_current_task_under_cgroup_user.c:57:6:
>      warning: variable 'cg2' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
> 	    if (setup_cgroup_environment())
> 		^~~~~~~~~~~~~~~~~~~~~~~~~~
>      ./samples/bpf/test_current_task_under_cgroup_user.c:106:8:
>      note: uninitialized use occurs here
> 	    close(cg2);
> 		  ^~~
>      ./samples/bpf/test_current_task_under_cgroup_user.c:57:2:
>      note: remove the 'if' if its condition is always false
> 	    if (setup_cgroup_environment())
> 	    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>      ./samples/bpf/test_current_task_under_cgroup_user.c:19:9:
>      note: initialize the variable 'cg2' to silence this warning
> 	    int cg2, idx = 0, rc = 1;
> 		   ^
> 		    = 0
>      1 warning generated.
> 
> This commit resolve this compiler warning by pre-initialize the variable
> with error for safeguard.
> 
> Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>

Acked-by: Yonghong Song <yhs@...com>