linux-kernel - Re: [PATCH v2 02/36] kernel: use kernel_wait4() instead of sys

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Date:   Fri, 16 Mar 2018 16:58:31 +0000
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Dominik Brodowski <linux@...inikbrodowski.net>
Cc:     linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        viro@...iv.linux.org.uk, luto@...nel.org, mingo@...nel.org,
        akpm@...ux-foundation.org, arnd@...db.de,
        "Luis R . Rodriguez" <mcgrof@...nel.org>
Subject: Re: [PATCH v2 02/36] kernel: use kernel_wait4() instead of
 sys_wait4()

On Thu, Mar 15, 2018 at 08:04:55PM +0100, Dominik Brodowski wrote:
> diff --git a/kernel/umh.c b/kernel/umh.c
> index 18e5fa4b0e71..f4b557cadf08 100644
> --- a/kernel/umh.c
> +++ b/kernel/umh.c
> @@ -135,7 +135,7 @@ static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
>  		 *
>  		 * Thus the __user pointer cast is valid here.
>  		 */
> -		sys_wait4(pid, (int __user *)&ret, 0, NULL);
> +		kernel_wait4(pid, (int __user *)&ret, 0, NULL);
>  
>  		/*
>  		 * If ret is 0, either call_usermodehelper_exec_async failed and

There is also a reference to sys_wait4() usage on umh.c:

        /* If SIGCLD is ignored sys_wait4 won't populate the status. */         
        kernel_sigaction(SIGCHLD, SIG_DFL);     

Does that remain true for kernel_wait4()? If so that comment should be updated
as well.

I don't see any kdoc for kernel_wait4(), can you update it and also clarify to
recommend it so that other users do the same? In fact not a kernel helper
which just takes no last argument, and passes NULL to kernel_wait4() as well?

  Luis