linux-kernel - Re: proc_dointvec() and write

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Message-ID: <4BFB56F1.1080200@redhat.com>
Date:	Tue, 25 May 2010 12:49:53 +0800
From:	Cong Wang <amwang@...hat.com>
To:	"J. R. Okajima" <hooanon05@...oo.co.jp>
CC:	opurdila@...acom.com, davem@...emloft.net,
	linux-kernel@...r.kernel.org
Subject: Re: proc_dointvec() and write

On 05/24/10 22:32, J. R. Okajima wrote:
> The commit 00b7c3395aec3df43de5bd02a3c5a099ca51169f
> "sysctl: refactor integer handling proc code"
> modified the behaviour of writing to /proc.
>
> Before the commit, write("1\n") to /proc/sys/kernel/printk succeeded. But
> now it returns EINVAL. Is this intended change? If not, how about this
> patch?
>


Hmm, odd, I tested other proc files, I see no problem.
I am wondering why /proc/sys/kernel/printk is special here.

I will be back later.

>
> J. R. Okajima
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 4c93486..5058e12 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2262,6 +2272,8 @@ static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
>   		if (write) {
>   			left -= proc_skip_spaces(&kbuf);
>
> +			if (!left)
> +				break;
>   			err = proc_get_long(&kbuf,&left,&lval,&neg,
>   					     proc_wspace_sep,
>   					     sizeof(proc_wspace_sep), NULL);
> @@ -2288,7 +2306,7 @@ static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
>
>   	if (!write&&  !first&&  left&&  !err)
>   		err = proc_put_char(&buffer,&left, '\n');
> -	if (write&&  !err)
> +	if (write&&  !err&&  left)
>   		left -= proc_skip_spaces(&kbuf);
>   free:
>   	if (write) {
>

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