From: Pan Xinhui <xinhui@linux.vnet.ibm.com>
To: Jia He <hejianet@gmail.com>, linux-nfs@vger.kernel.org
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@poochiereds.net>,
Trond Myklebust <trond.myklebust@primarydata.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/1] lockd: Change nsm_use_hostnames from bool to u32
Date: Mon, 12 Dec 2016 01:56:46 +0800 [thread overview]
Message-ID: <4757a896-6eb8-9d9a-fde0-bb9caa6e541e@linux.vnet.ibm.com> (raw)
In-Reply-To: <1481470609-31488-1-git-send-email-hejianet@gmail.com>
在 2016/12/11 23:36, Jia He 写道:
> nsm_use_hostnames is a module parameter and it will be exported to sysctl
> procfs. This is to let user sometimes change it from userspace. But the
> minimal unit for sysctl procfs read/write it sizeof(int).
> In big endian system, the converting from/to bool to/from int will cause
> error for proc items.
hi, Jia
not only in BE system. :)
Current code is just touching a wrong pointer.
some tests based on yours
u8 __read_mostly nsm_use_hostnames[4]={1,2,3,4}; // an arrary of u8, and [0] passed to ctl_table as data
static struct ctl_table my_sysctl[] = {
{
.procname = "nsm_use_hostnames",
.data = &nsm_use_hostnames[0],//u8,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{}
};
then run your tests and result will be
root@ltcalpine2-lp13:~/linux/bench# cat /proc/sys/mysysctl/nsm_use_hostnames
67305985( This is 0x4030201, expected be 0x1)
So your fix patch work around it. But I suggest we can support u8/u16, not only int/double int.
thanks
xinhui
>
> This patch changes the type definition of nsm_use_hostnames.
>
> The test case I used:
> /***************************************************************/
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/sysctl.h>
>
> bool __read_mostly nsm_use_hostnames;
> module_param(nsm_use_hostnames, bool, 0644);
>
> static struct ctl_table my_sysctl[] = {
> {
> .procname = "nsm_use_hostnames",
> .data = &nsm_use_hostnames,
> .maxlen = sizeof(int),
> .mode = 0644,
> .proc_handler = &proc_dointvec,
> },
> {}
> };
>
> static struct ctl_table my_root[] = {
> {
> .procname = "mysysctl",
> .mode = 0555,
> .child = my_sysctl,
> },
> {}
> };
>
> static struct ctl_table_header * my_ctl_header;
>
> static int __init sysctl_exam_init(void)
> {
> my_ctl_header = register_sysctl_table(&my_root);
> if (my_ctl_header == NULL)
> printk("error regiester sysctl");
>
> return 0;
> }
>
> static void __exit sysctl_exam_exit(void)
> {
> unregister_sysctl_table(my_ctl_header);
> }
>
> module_init(sysctl_exam_init);
> module_exit(sysctl_exam_exit);
> MODULE_LICENSE("GPL");
> /****************************************************************/
>
> [root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1
> [root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames
> 16777216
>
> After I change the bool to int:
> [root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1
> [root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames
> 1
>
> In little endian system, there is no such issue.
>
> Jia He (1):
> lockd: Change nsm_use_hostnames from bool to u32
>
> fs/lockd/mon.c | 2 +-
> fs/lockd/svc.c | 2 +-
> include/linux/lockd/lockd.h | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
prev parent reply other threads:[~2016-12-11 17:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-11 15:36 [PATCH v2 0/1] lockd: Change nsm_use_hostnames from bool to u32 Jia He
2016-12-11 15:36 ` [PATCH v2 1/1] " Jia He
2016-12-11 17:43 ` Pan Xinhui
2016-12-11 18:03 ` Pan Xinhui
2016-12-12 2:48 ` hejianet
2016-12-12 12:54 ` kbuild test robot
2016-12-11 17:56 ` Pan Xinhui [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4757a896-6eb8-9d9a-fde0-bb9caa6e541e@linux.vnet.ibm.com \
--to=xinhui@linux.vnet.ibm.com \
--cc=anna.schumaker@netapp.com \
--cc=bfields@fieldses.org \
--cc=hejianet@gmail.com \
--cc=jlayton@poochiereds.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nfs@vger.kernel.org \
--cc=trond.myklebust@primarydata.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).