linux-kernel - Re: [PATCH 1/5] Split wait_noreap

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Message-ID: <873aa9wib2.wl%vmayatsk@redhat.com>
Date:	Tue, 09 Jun 2009 17:14:25 +0200
From:	Vitaly Mayatskikh <v.mayatskih@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] Split wait_noreap_copyout()

Hi, Andrew!

Can you, please, update description of
wait_task_-cleanups-split-wait_noreap_copyout.patch?

New description:
----------------------------------------------------------------------
Move getrusage() and put_user() code from wait_noreap_copyout()
to copy_wait_opts_to_user(). The same code is spreaded across all
wait_task_*() routines, it's better to reuse one copy.

User visible change: previously, waitid() was doing unconditional
put_user() in wait_noreap_copyout(), and was returning EFAULT
if infop pointer, provided by user, was NULL *and* WCONTINUED was not
set in options. Now all variants of wait() function use the same generic
copy_wait_opts_to_user(), and, thus, have the same behaviour regarding
to filling of siginfo structure. Starting from this commit waitid()
returns NULL if infop argument is NULL.
----------------------------------------------------------------------

Thanks!

> 
> Move getrusage() and put_user() code from wait_noreap_copyout()
> to copy_wait_opts_to_user(). The same code is spreaded across all
> wait_task_*() routines, it's better to reuse one copy.
> 
> Signed-off-by: Vitaly Mayatskikh <v.mayatskih@...il.com>
> ---
>  kernel/exit.c |   39 +++++++++++++++++++++++----------------
>  1 files changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/kernel/exit.c b/kernel/exit.c
> index 25782da..9546362 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -1123,27 +1123,34 @@ static int eligible_child(struct wait_opts *wo, struct task_struct *p)
>  	return 1;
>  }
>  
> -static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
> -				pid_t pid, uid_t uid, int why, int status)
> +static int copy_wait_opts_to_user(struct wait_opts *wo, struct task_struct *p,
> +				  pid_t pid, uid_t uid, int why, int status, int signal)
>  {
> -	struct siginfo __user *infop;
> +	struct siginfo __user *infop = wo->wo_info;
>  	int retval = wo->wo_rusage
>  		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
>  
> +	if (!retval && infop) {
> +		retval = put_user(signal, &infop->si_signo);
> +		if (!retval)
> +			retval = put_user(0, &infop->si_errno);
> +		if (!retval)
> +			retval = put_user((short)why, &infop->si_code);
> +		if (!retval)
> +			retval = put_user(pid, &infop->si_pid);
> +		if (!retval)
> +			retval = put_user(uid, &infop->si_uid);
> +		if (!retval)
> +			retval = put_user(status, &infop->si_status);
> +	}
> +	return retval;
> +}
> +
> +static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
> +				pid_t pid, uid_t uid, int why, int status)
> +{
> +	int retval = copy_wait_opts_to_user(wo, p, pid, uid, why, status, SIGCHLD);
>  	put_task_struct(p);
> -	infop = wo->wo_info;
> -	if (!retval)
> -		retval = put_user(SIGCHLD, &infop->si_signo);
> -	if (!retval)
> -		retval = put_user(0, &infop->si_errno);
> -	if (!retval)
> -		retval = put_user((short)why, &infop->si_code);
> -	if (!retval)
> -		retval = put_user(pid, &infop->si_pid);
> -	if (!retval)
> -		retval = put_user(uid, &infop->si_uid);
> -	if (!retval)
> -		retval = put_user(status, &infop->si_status);
>  	if (!retval)
>  		retval = pid;
>  	return retval;
> -- 
> 1.6.2.2
> 
> 

-- 
wbr, Vitaly
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