sysctl: fix duplicate path separator in printed entries

sysctl_print_dir() always terminates the printed path name with a slash,
so printing a slash before the file part causes a duplicate like in

    sysctl duplicate entry: /kernel//perf_user_access

Fix this by dropping the extra slash.

Link: https://lkml.kernel.org/r/e3054d605dc56f83971e4b6d2f5fa63a978720ad.1641551872.git.geert+renesas@glider.beSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/proc_sysctl.c

@@ -163,7 +163,7 @@ static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
 		else {
 			pr_err("sysctl duplicate entry: ");
 			sysctl_print_dir(head->parent);
-			pr_cont("/%s\n", entry->procname);
+			pr_cont("%s\n", entry->procname);
 			return -EEXIST;
 		}
 	}
@@ -1020,8 +1020,8 @@ static struct ctl_dir *get_subdir(struct ctl_dir *dir,
 	if (IS_ERR(subdir)) {
 		pr_err("sysctl could not get directory: ");
 		sysctl_print_dir(dir);
-		pr_cont("/%*.*s %ld\n",
-			namelen, namelen, name, PTR_ERR(subdir));
+		pr_cont("%*.*s %ld\n", namelen, namelen, name,
+			PTR_ERR(subdir));
 	}
 	drop_sysctl_table(&dir->header);
 	if (new)
@@ -1626,7 +1626,7 @@ static void put_links(struct ctl_table_header *header)
 		else {
 			pr_err("sysctl link missing during unregister: ");
 			sysctl_print_dir(parent);
-			pr_cont("/%s\n", name);
+			pr_cont("%s\n", name);
 		}
 	}
 }