linux-kernel - Re: [PATCH next 0/3] debugfs: introduce debugfs_create_single/seq[,

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Date:   Fri, 29 Nov 2019 23:16:38 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH next 0/3] debugfs: introduce
 debugfs_create_single/seq[,_data]



On 2019/11/29 22:21, Greg KH wrote:
> On Fri, Nov 29, 2019 at 05:27:49PM +0800, Kefeng Wang wrote:
>> Like proc_create_single/seq[,_data] in procfs, we could provide similar debugfs
>> helper to reduce losts of boilerplate code.
>>
>> debugfs_create_single[,_data]
>>   creates a file in debugfs with the extra data and a seq_file show callback.
>> debugfs_create_seq[,_data]
>>   creates a file in debugfs with the extra data and a seq_operations.
>>
>> There is a object dynamically allocated in the helper, which is used to store
>> extra data, we need free it when remove the debugfs file.
>>
>> If the change is acceptable, we could change the caller one by one.
> 
> I would like to see a user of this and how you would convert it, in
> order to see if this is worth it or not.

I have some diff patches, the conversion is in progress. current statistics
are as follows,

1) debugfs: switch to debugfs_create_seq[,_data]
19 files changed, 85 insertions(+), 620 deletions(-)
2) debugfs: switch to debugfs_create_single[,_data]
70 files changed, 249 insertions(+), 1482 deletions(-)

Here are some examples,
1) debugfs_create_seq
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 78d53378db99..62c26772f24c 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -2057,18 +2057,6 @@ static const struct seq_operations unusable_op = {
 	.show	= unusable_show,
 };

-static int unusable_open(struct inode *inode, struct file *file)
-{
-	return seq_open(file, &unusable_op);
-}
-
-static const struct file_operations unusable_file_ops = {
-	.open		= unusable_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};
-
 static void extfrag_show_print(struct seq_file *m,
 					pg_data_t *pgdat, struct zone *zone)
 {
@@ -2109,29 +2097,17 @@ static const struct seq_operations extfrag_op = {
 	.show	= extfrag_show,
 };

-static int extfrag_open(struct inode *inode, struct file *file)
-{
-	return seq_open(file, &extfrag_op);
-}
-
-static const struct file_operations extfrag_file_ops = {
-	.open		= extfrag_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};
-
 static int __init extfrag_debug_init(void)
 {
 	struct dentry *extfrag_debug_root;

 	extfrag_debug_root = debugfs_create_dir("extfrag", NULL);

-	debugfs_create_file("unusable_index", 0444, extfrag_debug_root, NULL,
-			    &unusable_file_ops);
+	debugfs_create_seq("unusable_index", 0444, extfrag_debug_root,
+			   &unusable_op);

-	debugfs_create_file("extfrag_index", 0444, extfrag_debug_root, NULL,
-			    &extfrag_file_ops);
+	debugfs_create_seq("extfrag_index", 0444, extfrag_debug_root,
+			   &extfrag_op);

 	return 0;
 }

2) debugfs_create_single_data()
diff --git a/net/hsr/hsr_debugfs.c b/net/hsr/hsr_debugfs.c
index 94447974a3c0..8bdd70af02c9 100644
--- a/net/hsr/hsr_debugfs.c
+++ b/net/hsr/hsr_debugfs.c
@@ -52,25 +52,6 @@ hsr_node_table_show(struct seq_file *sfp, void *data)
 	return 0;
 }

-/* hsr_node_table_open - Open the node_table file
- *
- * Description:
- * This routine opens a debugfs file node_table of specific hsr device
- */
-static int
-hsr_node_table_open(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, hsr_node_table_show, inode->i_private);
-}
-
-static const struct file_operations hsr_fops = {
-	.owner	= THIS_MODULE,
-	.open	= hsr_node_table_open,
-	.read	= seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
-
 /* hsr_debugfs_init - create hsr node_table file for dumping
  * the node table
  *
@@ -91,9 +72,9 @@ int hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)

 	priv->node_tbl_root = de;

-	de = debugfs_create_file("node_table", S_IFREG | 0444,
-				 priv->node_tbl_root, priv,
-				 &hsr_fops);
+	de = debugfs_create_single_data("node_table", S_IFREG | 0444,
+					priv->node_tbl_root, priv,
+					hsr_node_table_show);
 	if (!de) {
 		pr_err("Cannot create hsr node_table directory\n");
 		return rc;
-- 
2.20.1


> 
> When you redo this series, can you add that to the end of it?
> 
> thanks,
> 
> greg k-h
> 
> .
>