Re: [PATCH mptcp-next] selftests: mptcp: diag: use mptcp_lib_get_info_value

[Gang Yan <yangang@kylinos.cn>]

On Thu, Apr 03, 2025 at 03:46:37PM +0800, Geliang Tang wrote:
Hi, Geliang:

Thanks for the patch, this patch also works well in my enviroment.
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> When running diag.sh in a loop, chk_dump_one will report the following
> "grep: write error":
> 
>  13 ....chk 2 cestab                                  [ OK ]
>  grep: write error
>  14 ....chk dump_one                                  [ OK ]
>  15 ....chk 2->0 msk in use after flush               [ OK ]
>  16 ....chk 2->0 cestab after flush                   [ OK ]
> 
> This error is caused by a broken pipe. When the output of 'ss' is processed
> by grep, 'head -n 1' will exit immediately after getting the first line,
> causing the subsequent pipe to close. At this time, if 'grep' is still
> trying to write data to the closed pipe, it will trigger a SIGPIPE signal,
> causing a write error.
> 
> One solution is not to use this problematic "head -n 1" command, but to use
> mptcp_lib_get_info_value() helper defined in mptcp_lib.sh to get the value
> of 'token'.
> 
> Fixes: ba2400166570 ("selftests: mptcp: add a test for mptcp_diag_dump_one")
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Tested-by: Gang Yan <yangang@kylinos.cn>
> ---
>  tools/testing/selftests/net/mptcp/diag.sh | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
> index 4f55477ffe08..e7a75341f0f3 100755
> --- a/tools/testing/selftests/net/mptcp/diag.sh
> +++ b/tools/testing/selftests/net/mptcp/diag.sh
> @@ -206,9 +206,8 @@ chk_dump_one()
>  	local token
>  	local msg
>  
> -	ss_token="$(ss -inmHMN $ns | grep 'token:' |\
> -		    head -n 1 |\
> -		    sed 's/.*token:\([0-9a-f]*\).*/\1/')"
> +	ss_token="$(ss -inmHMN $ns |
> +		    mptcp_lib_get_info_value "token" "token")"
>  
>  	token="$(ip netns exec $ns ./mptcp_diag -t $ss_token |\
>  		 awk -F':[ \t]+' '/^token/ {print $2}')"
> -- 
> 2.43.0
> 
> 
Best wishes!
Gang