[PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[Wang Chen]

Use proc_create() to make sure that ->proc_fops be setup before gluing
PDE to main tree.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
---
 net/sunrpc/cache.c |   14 ++++++--------
 net/sunrpc/stats.c |    3 +--
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 636c8e0..b5f2786 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -316,31 +316,29 @@ static int create_cache_proc_entries(struct cache_detail *cd)
 	cd->proc_ent->owner = cd->owner;
 	cd->channel_ent = cd->content_ent = NULL;
 
-	p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR, cd->proc_ent);
+	p = proc_create("flush", S_IFREG|S_IRUSR|S_IWUSR,
+			cd->proc_ent, &cache_flush_operations);
 	cd->flush_ent = p;
 	if (p == NULL)
 		goto out_nomem;
-	p->proc_fops = &cache_flush_operations;
 	p->owner = cd->owner;
 	p->data = cd;
 
 	if (cd->cache_request || cd->cache_parse) {
-		p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
-				      cd->proc_ent);
+		p = proc_create("channel", S_IFREG|S_IRUSR|S_IWUSR,
+				cd->proc_ent, &cache_file_operations);
 		cd->channel_ent = p;
 		if (p == NULL)
 			goto out_nomem;
-		p->proc_fops = &cache_file_operations;
 		p->owner = cd->owner;
 		p->data = cd;
 	}
 	if (cd->cache_show) {
-		p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
-				      cd->proc_ent);
+		p = proc_create("content", S_IFREG|S_IRUSR|S_IWUSR,
+				cd->proc_ent, &content_file_operations);
 		cd->content_ent = p;
 		if (p == NULL)
 			goto out_nomem;
-		p->proc_fops = &content_file_operations;
 		p->owner = cd->owner;
 		p->data = cd;
 	}
diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c
index 5a16875..c6061a4 100644
--- a/net/sunrpc/stats.c
+++ b/net/sunrpc/stats.c
@@ -229,9 +229,8 @@ do_register(const char *name, void *data, const struct file_operations *fops)
 	rpc_proc_init();
 	dprintk("RPC:       registering /proc/net/rpc/%s\n", name);
 
-	ent = create_proc_entry(name, 0, proc_net_rpc);
+	ent = proc_create(name, 0, proc_net_rpc, fops);
 	if (ent) {
-		ent->proc_fops = fops;
 		ent->data = data;
 	}
 	return ent;
-- 
WCN

Re: [PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[David Miller]

From: Wang Chen <wangchen@cn.fujitsu.com>
Date: Thu, 28 Feb 2008 18:55:40 +0800

> Use proc_create() to make sure that ->proc_fops be setup before gluing
> PDE to main tree.
> 
> Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>

Applied.

> @@ -229,9 +229,8 @@ do_register(const char *name, void *data, const struct file_operations *fops)
>  	rpc_proc_init();
>  	dprintk("RPC:       registering /proc/net/rpc/%s\n", name);
>  
> -	ent = create_proc_entry(name, 0, proc_net_rpc);
> +	ent = proc_create(name, 0, proc_net_rpc, fops);
>  	if (ent) {
> -		ent->proc_fops = fops;
>  		ent->data = data;
>  	}
>  	return ent;

For this case it appears that ent->data has the same kind of
visibility problem that ent->proc_fops does.

Re: [PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[Wang Chen]

David Miller said the following on 2008-2-29 6:02:
> From: Wang Chen <wangchen@cn.fujitsu.com>
> Date: Thu, 28 Feb 2008 18:55:40 +0800
> 
>> Use proc_create() to make sure that ->proc_fops be setup before gluing
>> PDE to main tree.
>>
>> Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
> 
> Applied.
> 
>> @@ -229,9 +229,8 @@ do_register(const char *name, void *data, const struct file_operations *fops)
>>  	rpc_proc_init();
>>  	dprintk("RPC:       registering /proc/net/rpc/%s\n", name);
>>  
>> -	ent = create_proc_entry(name, 0, proc_net_rpc);
>> +	ent = proc_create(name, 0, proc_net_rpc, fops);
>>  	if (ent) {
>> -		ent->proc_fops = fops;
>>  		ent->data = data;
>>  	}
>>  	return ent;
> 
> For this case it appears that ent->data has the same kind of
> visibility problem that ent->proc_fops does.
> 

Thanks Dave, I will check whether ->data also has the visibility problem.

Re: [PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[Wang Chen]

Wang Chen said the following on 2008-2-29 13:26:
> David Miller said the following on 2008-2-29 6:02:
>> From: Wang Chen <wangchen@cn.fujitsu.com>
>> Date: Thu, 28 Feb 2008 18:55:40 +0800
>>
>>> Use proc_create() to make sure that ->proc_fops be setup before gluing
>>> PDE to main tree.
>>>
>>> Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
>> Applied.
>>
>>> @@ -229,9 +229,8 @@ do_register(const char *name, void *data, const struct file_operations *fops)
>>>  	rpc_proc_init();
>>>  	dprintk("RPC:       registering /proc/net/rpc/%s\n", name);
>>>  
>>> -	ent = create_proc_entry(name, 0, proc_net_rpc);
>>> +	ent = proc_create(name, 0, proc_net_rpc, fops);
>>>  	if (ent) {
>>> -		ent->proc_fops = fops;
>>>  		ent->data = data;
>>>  	}
>>>  	return ent;
>> For this case it appears that ent->data has the same kind of
>> visibility problem that ent->proc_fops does.
>>
> 
> Thanks Dave, I will check whether ->data also has the visibility problem.
> 

I have looked at the proc_create().
The reason for why we need to setup pde->proc_fops in proc_create() before
the pde be visible, is that proc_fops will be setuped in proc_register() and
and NULL of proc_fops will make proc_register() give pde an improper fops.

But, ->data and ->owner will not be affected by this instance.
So, it's safe to setup ->data and ->owner after visibility of pde.

Re: [PATCH 03/15] [SUNRPC]: Use proc_create() to setup ->proc_fops first

[Alexey Dobriyan]

On Fri, Feb 29, 2008 at 04:35:17PM +0800, Wang Chen wrote:
> Wang Chen said the following on 2008-2-29 13:26:
> > David Miller said the following on 2008-2-29 6:02:
> >> From: Wang Chen <wangchen@cn.fujitsu.com>
> >> Date: Thu, 28 Feb 2008 18:55:40 +0800
> >>
> >>> Use proc_create() to make sure that ->proc_fops be setup before gluing
> >>> PDE to main tree.
> >>>
> >>> Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
> >> Applied.
> >>
> >>> @@ -229,9 +229,8 @@ do_register(const char *name, void *data, const struct file_operations *fops)
> >>>  	rpc_proc_init();
> >>>  	dprintk("RPC:       registering /proc/net/rpc/%s\n", name);
> >>>  
> >>> -	ent = create_proc_entry(name, 0, proc_net_rpc);
> >>> +	ent = proc_create(name, 0, proc_net_rpc, fops);
> >>>  	if (ent) {
> >>> -		ent->proc_fops = fops;
> >>>  		ent->data = data;
> >>>  	}
> >>>  	return ent;
> >> For this case it appears that ent->data has the same kind of
> >> visibility problem that ent->proc_fops does.
> >>
> > 
> > Thanks Dave, I will check whether ->data also has the visibility problem.
> > 
> 
> I have looked at the proc_create().
> The reason for why we need to setup pde->proc_fops in proc_create() before
> the pde be visible, is that proc_fops will be setuped in proc_register() and
> and NULL of proc_fops will make proc_register() give pde an improper fops.
> 
> But, ->data and ->owner will not be affected by this instance.
> So, it's safe to setup ->data and ->owner after visibility of pde.

->owner is buggy, believed to be unnecessary and will thus die so don't
bother with it. ;-)

->data looks safe to setup separately while module is loading:
before ->data will be used by code which is unprepared to it being NULL,
VFS will pin module, which can't be done during module load.

I think the existence of proc_create_data() depends entirely on
cases which do all the above from code that is not module_init hook.
Does anyone know some?