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From: J. R. Okajima on 24 May 2010 10:40

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?


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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From: Cong Wang on 25 May 2010 00:50
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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From: J. R. Okajima on 25 May 2010 01:00

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

The condition is,
- the entry has multiple values, .maxlen = N * sizeof(foo)
- the entry is writable, .mode = 0644 (or something)

In sysctl.c, only "printk" and "acct" match.


J. R. Okajima
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From: Cong Wang on 25 May 2010 01:40
On 05/25/10 12:57, J. R. Okajima wrote:
> Cong Wang:
>> Hmm, odd, I tested other proc files, I see no problem.
>> I am wondering why /proc/sys/kernel/printk is special here.
>
> The condition is,
> - the entry has multiple values, .maxlen = N * sizeof(foo)
> - the entry is writable, .mode = 0644 (or something)
>
> In sysctl.c, only "printk" and "acct" match.

Hmm, right, I missed this case during testing.

Your patch looks correct for me. Would you mind to send your
patch again with your Signed-off-by?

Thank you!
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