[PATCH 2/2] cgroup: switch to proc_create()

[PATCH 2/2] cgroup: switch to proc_create()

[Li Zefan]

There is a race between create_proc_entry() and the assignment
of file ops. proc_create() is invented to fix it.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/cgroup.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8d833b6..8d45126 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2489,7 +2489,6 @@ int __init cgroup_init(void)
 {
 	int err;
 	int i;
-	struct proc_dir_entry *entry;
 
 	err = bdi_init(&cgroup_backing_dev_info);
 	if (err)
@@ -2505,9 +2504,7 @@ int __init cgroup_init(void)
 	if (err < 0)
 		goto out;
 
-	entry = create_proc_entry("cgroups", 0, NULL);
-	if (entry)
-		entry->proc_fops = &proc_cgroupstats_operations;
+	proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
 
 out:
 	if (err)
-- 
1.5.4.rc3

Re: [PATCH 2/2] cgroup: switch to proc_create()

[Paul Menage]

On Mon, Mar 10, 2008 at 12:30 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
> There is a race between create_proc_entry() and the assignment
>  of file ops. proc_create() is invented to fix it.
>
>  Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

Acked-by: Paul Menage <menage@google.com>

Doesn't seem to be a serious race since there's nothing in userspace
at this point to read the file. But replacing four lines with one is
generally a good thing.

Paul

>  ---
>   kernel/cgroup.c |    5 +----
>   1 files changed, 1 insertions(+), 4 deletions(-)
>
>  diff --git a/kernel/cgroup.c b/kernel/cgroup.c
>  index 8d833b6..8d45126 100644
>  --- a/kernel/cgroup.c
>  +++ b/kernel/cgroup.c
>  @@ -2489,7 +2489,6 @@ int __init cgroup_init(void)
>   {
>         int err;
>         int i;
>  -       struct proc_dir_entry *entry;
>
>         err = bdi_init(&cgroup_backing_dev_info);
>         if (err)
>  @@ -2505,9 +2504,7 @@ int __init cgroup_init(void)
>         if (err < 0)
>                 goto out;
>
>  -       entry = create_proc_entry("cgroups", 0, NULL);
>  -       if (entry)
>  -               entry->proc_fops = &proc_cgroupstats_operations;
>  +       proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
>
>   out:
>         if (err)
>  --
>  1.5.4.rc3
>

Re: [PATCH 2/2] cgroup: switch to proc_create()

[Li Zefan]

Paul Menage wrote:
> On Mon, Mar 10, 2008 at 12:30 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
>> There is a race between create_proc_entry() and the assignment
>>  of file ops. proc_create() is invented to fix it.
>>
>>  Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> 
> Acked-by: Paul Menage <menage@google.com>
> 
> Doesn't seem to be a serious race since there's nothing in userspace
> at this point to read the file. But replacing four lines with one is
> generally a good thing.
> 

Yes I know, it's a slight race in case of modular code, but the aim is 
to replace all the use of create_proc_entry() with proc_create(). :) 

> Paul
>