netconsole: Create a allocation helper

De-duplicate the initialization and allocation code for struct
netconsole_target.

The same allocation and initialization code is duplicated in two
different places in the netconsole subsystem, when the netconsole target
is initialized by command line parameters (alloc_param_target()), and
dynamically by sysfs (make_netconsole_target()).

Create a helper function, and call it from the two different functions.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230811093158.1678322-2-leitao@debian.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/netconsole.c

@@ -167,19 +167,16 @@ static void netconsole_target_put(struct netconsole_target *nt)
 
 #endif	/* CONFIG_NETCONSOLE_DYNAMIC */
 
-/* Allocate new target (from boot/module param) and setup netpoll for it */
-static struct netconsole_target *alloc_param_target(char *target_config)
+/* Allocate and initialize with defaults.
+ * Note that these targets get their config_item fields zeroed-out.
+ */
+static struct netconsole_target *alloc_and_init(void)
 {
-	int err = -ENOMEM;
 	struct netconsole_target *nt;
 
-	/*
-	 * Allocate and initialize with defaults.
-	 * Note that these targets get their config_item fields zeroed-out.
-	 */
 	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 	if (!nt)
-		goto fail;
+		return nt;
 
 	nt->np.name = "netconsole";
 	strscpy(nt->np.dev_name, "eth0", IFNAMSIZ);
@@ -187,6 +184,21 @@ static struct netconsole_target *alloc_param_target(char *target_config)
 	nt->np.remote_port = 6666;
 	eth_broadcast_addr(nt->np.remote_mac);
 
+	return nt;
+}
+
+/* Allocate new target (from boot/module param) and setup netpoll for it */
+static struct netconsole_target *alloc_param_target(char *target_config)
+{
+	struct netconsole_target *nt;
+	int err;
+
+	nt = alloc_and_init();
+	if (!nt) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
 	if (*target_config == '+') {
 		nt->extended = true;
 		target_config++;
@@ -195,6 +207,7 @@ static struct netconsole_target *alloc_param_target(char *target_config)
 	if (*target_config == 'r') {
 		if (!nt->extended) {
 			pr_err("Netconsole configuration error. Release feature requires extended log message");
+			err = -EINVAL;
 			goto fail;
 		}
 		nt->release = true;
@@ -664,23 +677,13 @@ static const struct config_item_type netconsole_target_type = {
 static struct config_item *make_netconsole_target(struct config_group *group,
 						  const char *name)
 {
-	unsigned long flags;
 	struct netconsole_target *nt;
+	unsigned long flags;
 
-	/*
-	 * Allocate and initialize with defaults.
-	 * Target is disabled at creation (!enabled).
-	 */
-	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
+	nt = alloc_and_init();
 	if (!nt)
 		return ERR_PTR(-ENOMEM);
 
-	nt->np.name = "netconsole";
-	strscpy(nt->np.dev_name, "eth0", IFNAMSIZ);
-	nt->np.local_port = 6665;
-	nt->np.remote_port = 6666;
-	eth_broadcast_addr(nt->np.remote_mac);
-
 	/* Initialize the config_item member */
 	config_item_init_type_name(&nt->item, name, &netconsole_target_type);