From: Xiaoming Ni <nixiaoming@huawei.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
<keescook@chromium.org>
Cc: <mcgrof@kernel.org>, <yzaikin@google.com>, <adobriyan@gmail.com>,
<mingo@kernel.org>, <gpiccoli@canonical.com>, <rdna@fb.com>,
<patrick.bellasi@arm.com>, <sfr@canb.auug.org.au>,
<akpm@linux-foundation.org>, <mhocko@suse.com>, <vbabka@suse.cz>,
<tglx@linutronix.de>, <peterz@infradead.org>,
<Jisheng.Zhang@synaptics.com>, <khlebnikov@yandex-team.ru>,
<bigeasy@linutronix.de>, <pmladek@suse.com>,
<linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
<wangle6@huawei.com>, <alex.huangjianhui@huawei.com>
Subject: Re: [PATCH v4 2/4] sysctl: Move some boundary constants form sysctl.c to sysctl_vals
Date: Wed, 20 May 2020 09:14:08 +0800 [thread overview]
Message-ID: <550a55b8-d2a8-0de3-0bed-8f93a4513efe@huawei.com> (raw)
In-Reply-To: <1bf1aefb-adfd-4f43-35c7-5b320d43faf8@i-love.sakura.ne.jp>
On 2020/5/19 12:44, Tetsuo Handa wrote:
> On 2020/05/19 12:31, Xiaoming Ni wrote:
>> Some boundary (.extra1 .extra2) constants (E.g: neg_one two) in
>> sysctl.c are used in multiple features. Move these variables to
>> sysctl_vals to avoid adding duplicate variables when cleaning up
>> sysctls table.
>>
>> Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> I feel that it is use of
>
> void *extra1;
> void *extra2;
>
> in "struct ctl_table" that requires constant values indirection.
> Can't we get rid of sysctl_vals using some "union" like below?
>
> struct ctl_table {
> const char *procname; /* Text ID for /proc/sys, or zero */
> void *data;
> int maxlen;
> umode_t mode;
> struct ctl_table *child; /* Deprecated */
> proc_handler *proc_handler; /* Callback for text formatting */
> struct ctl_table_poll *poll;
> union {
> void *min_max_ptr[2];
> int min_max_int[2];
> long min_max_long[2];
> };
> } __randomize_layout;
>
> .
>
net/decnet/dn_dev.c:
static void dn_dev_sysctl_register(struct net_device *dev, struct
dn_dev_parms *parms)
{
struct dn_dev_sysctl_table *t;
int i;
char path[sizeof("net/decnet/conf/") + IFNAMSIZ];
t = kmemdup(&dn_dev_sysctl, sizeof(*t), GFP_KERNEL);
if (t == NULL)
return;
for(i = 0; i < ARRAY_SIZE(t->dn_dev_vars) - 1; i++) {
long offset = (long)t->dn_dev_vars[i].data;
t->dn_dev_vars[i].data = ((char *)parms) + offset;
}
snprintf(path, sizeof(path), "net/decnet/conf/%s",
dev? dev->name : parms->name);
t->dn_dev_vars[0].extra1 = (void *)dev;
t->sysctl_header = register_net_sysctl(&init_net, path, t->dn_dev_vars);
if (t->sysctl_header == NULL)
kfree(t);
else
parms->sysctl = t;
}
A small amount of code is not used as a boundary value when using
extra1. This scenario may not be suitable for renaming to min_max_ptr.
Should we add const to extra1 extra2 ?
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -124,8 +124,8 @@ struct ctl_table {
struct ctl_table *child; /* Deprecated */
proc_handler *proc_handler; /* Callback for text formatting */
struct ctl_table_poll *poll;
- void *extra1;
- void *extra2;
+ const void *extra1;
+ const void *extra2;
} __randomize_layout;
Thanks
Xiaoming Ni
next prev parent reply other threads:[~2020-05-20 1:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 3:31 [PATCH v4 0/4] cleaning up the sysctls table (hung_task watchdog) Xiaoming Ni
2020-05-19 3:31 ` [PATCH v4 1/4] sysctl: Add register_sysctl_init() interface Xiaoming Ni
2020-05-29 7:09 ` Luis Chamberlain
2020-05-29 7:27 ` Xiaoming Ni
2020-05-29 7:36 ` Luis Chamberlain
2020-05-29 8:33 ` Xiaoming Ni
2020-05-29 11:31 ` Luis Chamberlain
2020-05-19 3:31 ` [PATCH v4 2/4] sysctl: Move some boundary constants form sysctl.c to sysctl_vals Xiaoming Ni
2020-05-19 4:44 ` Tetsuo Handa
2020-05-20 1:14 ` Xiaoming Ni [this message]
2020-05-20 1:39 ` Luis Chamberlain
2020-05-19 3:31 ` [PATCH v4 3/4] hung_task: Move hung_task sysctl interface to hung_task.c Xiaoming Ni
2020-05-19 3:31 ` [PATCH v4 4/4] watchdog: move watchdog sysctl interface to watchdog.c Xiaoming Ni
2020-05-20 3:31 ` [PATCH v4 0/4] cleaning up the sysctls table (hung_task watchdog) Andrew Morton
2020-05-20 4:02 ` Xiaoming Ni
2020-05-20 13:08 ` Luis Chamberlain
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