linux-kernel - [PATCH 02/11] proc_sysctl: move helper which creates required subdirectories

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Date:   Thu,  2 Mar 2023 12:28:17 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     ebiederm@...ssion.com, keescook@...omium.org, yzaikin@...gle.com,
        john.johansen@...onical.com, paul@...l-moore.com,
        jmorris@...ei.org, serge@...lyn.com, luto@...capital.net,
        wad@...omium.org, dverkamp@...omium.org, paulmck@...nel.org,
        baihaowen@...zu.com, frederic@...nel.org, jeffxu@...gle.com,
        ebiggers@...nel.org, tytso@....edu, guoren@...nel.org
Cc:     j.granados@...sung.com, zhangpeng362@...wei.com,
        tangmeng@...ontech.com, willy@...radead.org, nixiaoming@...wei.com,
        sujiaxun@...ontech.com, patches@...ts.linux.dev,
        linux-fsdevel@...r.kernel.org, apparmor@...ts.ubuntu.com,
        linux-security-module@...r.kernel.org, linux-csky@...r.kernel.org,
        linux-kernel@...r.kernel.org, Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH 02/11] proc_sysctl: move helper which creates required subdirectories

Move the code which creates the subdirectories for a ctl table
into a helper routine so to make it easier to review. Document
the goal.

This creates no functional changes.

Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 fs/proc/proc_sysctl.c | 56 ++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 24 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 1df0beb50dbe..6b9b2694d430 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1283,6 +1283,35 @@ static int insert_links(struct ctl_table_header *head)
 	return err;
 }
 
+/* Find the directory for the ctl_table. If one is not found create it. */
+static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
+{
+	const char *name, *nextname;
+
+	for (name = path; name; name = nextname) {
+		int namelen;
+		nextname = strchr(name, '/');
+		if (nextname) {
+			namelen = nextname - name;
+			nextname++;
+		} else {
+			namelen = strlen(name);
+		}
+		if (namelen == 0)
+			continue;
+
+		/*
+		 * namelen ensures if name is "foo/bar/yay" only foo is
+		 * registered first. We traverse as if using mkdir -p and
+		 * return a ctl_dir for the last directory entry.
+		 */
+		dir = get_subdir(dir, name, namelen);
+		if (IS_ERR(dir))
+			break;
+	}
+	return dir;
+}
+
 /**
  * __register_sysctl_table - register a leaf sysctl table
  * @set: Sysctl tree to register on
@@ -1334,7 +1363,6 @@ struct ctl_table_header *__register_sysctl_table(
 {
 	struct ctl_table_root *root = set->dir.header.root;
 	struct ctl_table_header *header;
-	const char *name, *nextname;
 	struct ctl_dir *dir;
 	struct ctl_table *entry;
 	struct ctl_node *node;
@@ -1359,29 +1387,9 @@ struct ctl_table_header *__register_sysctl_table(
 	dir->header.nreg++;
 	spin_unlock(&sysctl_lock);
 
-	/* Find the directory for the ctl_table */
-	for (name = path; name; name = nextname) {
-		int namelen;
-		nextname = strchr(name, '/');
-		if (nextname) {
-			namelen = nextname - name;
-			nextname++;
-		} else {
-			namelen = strlen(name);
-		}
-		if (namelen == 0)
-			continue;
-
-		/*
-		 * namelen ensures if name is "foo/bar/yay" only foo is
-		 * registered first. We traverse as if using mkdir -p and
-		 * return a ctl_dir for the last directory entry.
-		 */
-		dir = get_subdir(dir, name, namelen);
-		if (IS_ERR(dir))
-			goto fail;
-	}
-
+	dir = sysctl_mkdir_p(dir, path);
+	if (IS_ERR(dir))
+		goto fail;
 	spin_lock(&sysctl_lock);
 	if (insert_header(dir, header))
 		goto fail_put_dir_locked;
-- 
2.39.1