netdev - Re: [PATCH] ip: Exit exec in child process if setup fails

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Message-ID: <ZiF/rppvSxED2W8m@abode>
Date: Thu, 18 Apr 2024 23:16:46 +0300
From: Yedaya <yedaya.ka@...il.com>
To: netdev@...r.kernel.org
Cc: Stephen Hemminger <stephen@...workplumber.org>
Subject: Re: [PATCH] ip: Exit exec in child process if setup fails

Ping - in case you missed this

On Sun, Mar 24, 2024 at 06:34:36PM +0200, Yedaya Katsman wrote:
> If we forked, returning from the function will make the calling code to
> continue in both the child and parent process. Make cmd_exec exit if
> setup failed and it forked already.
> 
> An example of issues this causes, where a failure in setup causes
> multiple unnecessary tries:
> 
> ```
> $ ip netns
> ef
> ab
> $ ip -all netns exec ls
> 
> netns: ef
> setting the network namespace "ef" failed: Operation not permitted
> 
> netns: ab
> setting the network namespace "ab" failed: Operation not permitted
> 
> netns: ab
> setting the network namespace "ab" failed: Operation not permitted
> ```
> 
> Signed-off-by: Yedaya Katsman <yedaya.ka@...il.com>
> ---
>  lib/exec.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/exec.c b/lib/exec.c
> index 9b1c8f4a1396..893937550079 100644
> --- a/lib/exec.c
> +++ b/lib/exec.c
> @@ -36,8 +36,13 @@ int cmd_exec(const char *cmd, char **argv, bool do_fork,
>  		}
>  	}
>  
> -	if (setup && setup(arg))
> +	if (setup && setup(arg)) {
> +		if (do_fork) {
> +			/* In child, nothing to do */
> +			_exit(1);
> +		}
>  		return -1;
> +	}
>  
>  	if (execvp(cmd, argv)  < 0)
>  		fprintf(stderr, "exec of \"%s\" failed: %s\n",
> -- 
> 2.34.1
>