parport: Remove register_sysctl_table from parport_proc_register

This is part of the general push to deprecate register_sysctl_paths and
register_sysctl_table. Register dev/parport/PORTNAME and
dev/parport/PORTNAME/devices. Temporary allocation for name is freed at
the end of the function. Remove all the struct elements that are no
longer used in the parport_device_sysctl_template struct. Add parport
specific defines that hide the base path sizes.

To make sure the resulting directory structure did not change we
made sure that `find /proc/sys/dev/ | sha1sum` was the same before and
after the change.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202305150948.pHgIh7Ql-lkp@intel.com/
Reported-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/drivers/parport/procfs.c b/drivers/parport/procfs.c
index d740eba..28a37e0 100644 (file)
--- a/drivers/parport/procfs.c
+++ b/drivers/parport/procfs.c
@@ -32,6 +32,13 @@
 #define PARPORT_MAX_TIMESLICE_VALUE ((unsigned long) HZ)
 #define PARPORT_MIN_SPINTIME_VALUE 1
 #define PARPORT_MAX_SPINTIME_VALUE 1000
+/*
+ * PARPORT_BASE_* is the size of the known parts of the sysctl path
+ * in dev/partport/%s/devices/%s. "dev/parport/"(12), "/devices/"(9
+ * and null char(1).
+ */
+#define PARPORT_BASE_PATH_SIZE 13
+#define PARPORT_BASE_DEVICES_PATH_SIZE 22
 
 static int do_active_device(struct ctl_table *table, int write,
                      void *result, size_t *lenp, loff_t *ppos)
@@ -260,9 +267,6 @@ struct parport_sysctl_table {
        struct ctl_table_header *sysctl_header;
        struct ctl_table vars[12];
        struct ctl_table device_dir[2];
-       struct ctl_table port_dir[2];
-       struct ctl_table parport_dir[2];
-       struct ctl_table dev_dir[2];
 };
 
 static const struct parport_sysctl_table parport_sysctl_template = {
@@ -305,7 +309,6 @@ static const struct parport_sysctl_table parport_sysctl_template = {
                        .mode           = 0444,
                        .proc_handler   = do_hardware_modes
                },
-               PARPORT_DEVICES_ROOT_DIR,
 #ifdef CONFIG_PARPORT_1284
                {
                        .procname       = "autoprobe",
@@ -355,18 +358,6 @@ static const struct parport_sysctl_table parport_sysctl_template = {
                },
                {}
        },
-       {
-               PARPORT_PORT_DIR(NULL),
-               {}
-       },
-       {
-               PARPORT_PARPORT_DIR(NULL),
-               {}
-       },
-       {
-               PARPORT_DEV_DIR(NULL),
-               {}
-       }
 };
 
 struct parport_device_sysctl_table
@@ -473,11 +464,13 @@ parport_default_sysctl_table = {
        }
 };
 
-
 int parport_proc_register(struct parport *port)
 {
        struct parport_sysctl_table *t;
-       int i;
+       struct ctl_table_header *devices_h;
+       char *tmp_dir_path;
+       size_t tmp_path_len, port_name_len;
+       int bytes_written, i, err = 0;
 
        t = kmemdup(&parport_sysctl_template, sizeof(*t), GFP_KERNEL);
        if (t == NULL)
@@ -485,28 +478,64 @@ int parport_proc_register(struct parport *port)
 
        t->device_dir[0].extra1 = port;
 
-       for (i = 0; i < 5; i++)
+       t->vars[0].data = &port->spintime;
+       for (i = 0; i < 5; i++) {
                t->vars[i].extra1 = port;
+               t->vars[5 + i].extra2 = &port->probe_info[i];
+       }
 
-       t->vars[0].data = &port->spintime;
-       t->vars[5].child = t->device_dir;
-       
-       for (i = 0; i < 5; i++)
-               t->vars[6 + i].extra2 = &port->probe_info[i];
+       port_name_len = strnlen(port->name, PARPORT_NAME_MAX_LEN);
+       /*
+        * Allocate a buffer for two paths: dev/parport/PORT and dev/parport/PORT/devices.
+        * We calculate for the second as that will give us enough for the first.
+        */
+       tmp_path_len = PARPORT_BASE_DEVICES_PATH_SIZE + port_name_len;
+       tmp_dir_path = kzalloc(tmp_path_len, GFP_KERNEL);
+       if (!tmp_dir_path) {
+               err = -ENOMEM;
+               goto exit_free_t;
+       }
 
-       t->port_dir[0].procname = port->name;
+       bytes_written = snprintf(tmp_dir_path, tmp_path_len,
+                                "dev/parport/%s/devices", port->name);
+       if (tmp_path_len <= bytes_written) {
+               err = -ENOENT;
+               goto exit_free_tmp_dir_path;
+       }
+       devices_h = register_sysctl(tmp_dir_path, t->device_dir);
+       if (devices_h == NULL) {
+               err = -ENOENT;
+               goto  exit_free_tmp_dir_path;
+       }
 
-       t->port_dir[0].child = t->vars;
-       t->parport_dir[0].child = t->port_dir;
-       t->dev_dir[0].child = t->parport_dir;
+       tmp_path_len = PARPORT_BASE_PATH_SIZE + port_name_len;
+       bytes_written = snprintf(tmp_dir_path, tmp_path_len,
+                                "dev/parport/%s", port->name);
+       if (tmp_path_len <= bytes_written) {
+               err = -ENOENT;
+               goto unregister_devices_h;
+       }
 
-       t->sysctl_header = register_sysctl_table(t->dev_dir);
+       t->sysctl_header = register_sysctl(tmp_dir_path, t->vars);
        if (t->sysctl_header == NULL) {
-               kfree(t);
-               t = NULL;
+               err = -ENOENT;
+               goto unregister_devices_h;
        }
+
        port->sysctl_table = t;
+
+       kfree(tmp_dir_path);
        return 0;
+
+unregister_devices_h:
+       unregister_sysctl_table(devices_h);
+
+exit_free_tmp_dir_path:
+       kfree(tmp_dir_path);
+
+exit_free_t:
+       kfree(t);
+       return err;
 }
 
 int parport_proc_unregister(struct parport *port)