parport: Use kasprintf() instead of fixed buffer formatting

Improve readability and maintainability by replacing a hardcoded string
allocation and formatting by the use of the kasprintf() helper.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231016133135.1203643-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/parport/procfs.c

@@ -32,13 +32,6 @@
 #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)
@@ -431,8 +424,7 @@ int parport_proc_register(struct parport *port)
 {
 	struct parport_sysctl_table *t;
 	char *tmp_dir_path;
-	size_t tmp_path_len, port_name_len;
+	int i, err = 0;
-	int bytes_written, i, err = 0;
 
 	t = kmemdup(&parport_sysctl_template, sizeof(*t), GFP_KERNEL);
 	if (t == NULL)
@@ -446,35 +438,23 @@ int parport_proc_register(struct parport *port)
 		t->vars[5 + i].extra2 = &port->probe_info[i];
 	}
 
-	port_name_len = strnlen(port->name, PARPORT_NAME_MAX_LEN);
+	tmp_dir_path = kasprintf(GFP_KERNEL, "dev/parport/%s/devices", port->name);
-	/*
-	 * 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;
 	}
 
-	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;
-	}
 	t->devices_header = register_sysctl(tmp_dir_path, t->device_dir);
 	if (t->devices_header == NULL) {
 		err = -ENOENT;
 		goto  exit_free_tmp_dir_path;
 	}
 
-	tmp_path_len = PARPORT_BASE_PATH_SIZE + port_name_len;
+	kfree(tmp_dir_path);
-	bytes_written = snprintf(tmp_dir_path, tmp_path_len,
+
-				 "dev/parport/%s", port->name);
+	tmp_dir_path = kasprintf(GFP_KERNEL, "dev/parport/%s", port->name);
-	if (tmp_path_len <= bytes_written) {
+	if (!tmp_dir_path) {
-		err = -ENOENT;
+		err = -ENOMEM;
 		goto unregister_devices_h;
 	}
 
@@ -514,34 +494,22 @@ int parport_proc_unregister(struct parport *port)
 
 int parport_device_proc_register(struct pardevice *device)
 {
-	int bytes_written, err = 0;
 	struct parport_device_sysctl_table *t;
 	struct parport * port = device->port;
-	size_t port_name_len, device_name_len, tmp_dir_path_len;
 	char *tmp_dir_path;
+	int err = 0;
 	
 	t = kmemdup(&parport_device_sysctl_template, sizeof(*t), GFP_KERNEL);
 	if (t == NULL)
 		return -ENOMEM;
 
-	port_name_len = strnlen(port->name, PARPORT_NAME_MAX_LEN);
-	device_name_len = strnlen(device->name, PATH_MAX);
-
 	/* Allocate a buffer for two paths: dev/parport/PORT/devices/DEVICE. */
-	tmp_dir_path_len = PARPORT_BASE_DEVICES_PATH_SIZE + port_name_len + device_name_len;
+	tmp_dir_path = kasprintf(GFP_KERNEL, "dev/parport/%s/devices/%s", port->name, device->name);
-	tmp_dir_path = kzalloc(tmp_dir_path_len, GFP_KERNEL);
 	if (!tmp_dir_path) {
 		err = -ENOMEM;
 		goto exit_free_t;
 	}
 
-	bytes_written = snprintf(tmp_dir_path, tmp_dir_path_len, "dev/parport/%s/devices/%s",
-				 port->name, device->name);
-	if (tmp_dir_path_len <= bytes_written) {
-		err = -ENOENT;
-		goto exit_free_path;
-	}
-
 	t->vars[0].data = &device->timeslice;
 
 	t->sysctl_header = register_sysctl(tmp_dir_path, t->vars);
@@ -554,9 +522,6 @@ int parport_device_proc_register(struct pardevice *device)
 	kfree(tmp_dir_path);
 	return 0;
 
-exit_free_path:
-	kfree(tmp_dir_path);
-
 exit_free_t:
 	kfree(t);
 

drivers/parport/share.c

@@ -438,7 +438,6 @@ struct parport *parport_register_port(unsigned long base, int irq, int dma,
 	struct parport *tmp;
 	int num;
 	int device;
-	char *name;
 	int ret;
 
 	tmp = kzalloc(sizeof(struct parport), GFP_KERNEL);
@@ -467,11 +466,6 @@ struct parport *parport_register_port(unsigned long base, int irq, int dma,
 	atomic_set(&tmp->ref_count, 1);
 	INIT_LIST_HEAD(&tmp->full_list);
 
-	name = kmalloc(PARPORT_NAME_MAX_LEN, GFP_KERNEL);
-	if (!name) {
-		kfree(tmp);
-		return NULL;
-	}
 	/* Search for the lowest free parport number. */
 
 	spin_lock(&full_list_lock);
@@ -487,11 +481,14 @@ struct parport *parport_register_port(unsigned long base, int irq, int dma,
 	/*
 	 * Now that the portnum is known finish doing the Init.
 	 */
-	sprintf(name, "parport%d", tmp->portnum = tmp->number);
+	tmp->name = kasprintf(GFP_KERNEL, "parport%d", tmp->portnum);
-	tmp->name = name;
+	if (!tmp->name) {
+		kfree(tmp);
+		return NULL;
+	}
+	dev_set_name(&tmp->bus_dev, tmp->name);
 	tmp->bus_dev.bus = &parport_bus_type;
 	tmp->bus_dev.release = free_port;
-	dev_set_name(&tmp->bus_dev, name);
 	tmp->bus_dev.type = &parport_device_type;
 
 	for (device = 0; device < 5; device++)

include/linux/parport.h

@@ -180,8 +180,6 @@ struct ieee1284_info {
 	struct semaphore irq;
 };
 
-#define PARPORT_NAME_MAX_LEN 15
-
 /* A parallel port */
 struct parport {
 	unsigned long base;	/* base address */