wip: usb sysctl init

drivers/usb/core/Makefile

@@ -11,6 +11,7 @@ usbcore-y += phy.o port.o
 usbcore-$(CONFIG_OF)		+= of.o
 usbcore-$(CONFIG_USB_PCI)		+= hcd-pci.o
 usbcore-$(CONFIG_ACPI)		+= usb-acpi.o
+usbcore-$(CONFIG_SYSCTL)		+= sysctl.o
 
 obj-$(CONFIG_USB)		+= usbcore.o
 

drivers/usb/core/hub.c

@@ -5054,9 +5054,6 @@ static int descriptors_changed(struct usb_device *udev,
 	return changed;
 }
 
-/* sysctl */
-int deny_new_usb __read_mostly = 0;
-
 static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
 		u16 portchange)
 {

drivers/usb/core/sysctl.c

@@ -0,0 +1,44 @@
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kmemleak.h>
+#include <linux/sysctl.h>
+#include <linux/usb.h>
+
+static struct ctl_table usb_table[] = {
+	{
+		.procname	= "deny_new_usb",
+		.data		= &deny_new_usb,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax_sysadmin,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{ }
+};
+
+static struct ctl_table usb_root_table[] = {
+	{ .procname	= "kernel",
+	  .mode		= 0555,
+	  .child	= usb_table },
+	{ }
+};
+
+static struct ctl_table_header *usb_table_header;
+
+int __init usb_init_sysctl(void)
+{
+	usb_table_header = register_sysctl_table(usb_root_table);
+	if (!usb_table_header) {
+		pr_warn("usb: sysctl registration failed\n");
+		return -ENOMEM;
+	}
+
+	kmemleak_not_leak(usb_table_header);
+	return 0;
+}
+
+void usb_exit_sysctl(void)
+{
+	unregister_sysctl_table(usb_table_header);
+}

drivers/usb/core/usb.c

@@ -72,6 +72,9 @@ MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
 #define usb_autosuspend_delay		0
 #endif
 
+int deny_new_usb __read_mostly = 0;
+EXPORT_SYMBOL(deny_new_usb);
+
 static bool match_endpoint(struct usb_endpoint_descriptor *epd,
 		struct usb_endpoint_descriptor **bulk_in,
 		struct usb_endpoint_descriptor **bulk_out,
@@ -978,6 +981,9 @@ static int __init usb_init(void)
 	usb_debugfs_init();
 
 	usb_acpi_register();
+	retval = usb_init_sysctl();
+	if (retval)
+		goto sysctl_init_failed;
 	retval = bus_register(&usb_bus_type);
 	if (retval)
 		goto bus_register_failed;
@@ -1012,6 +1018,8 @@ static int __init usb_init(void)
 bus_notifier_failed:
 	bus_unregister(&usb_bus_type);
 bus_register_failed:
+	usb_exit_sysctl();
+sysctl_init_failed:
 	usb_acpi_unregister();
 	usb_debugfs_cleanup();
 out:
@@ -1035,6 +1043,7 @@ static void __exit usb_exit(void)
 	usb_hub_cleanup();
 	bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
 	bus_unregister(&usb_bus_type);
+	usb_exit_sysctl();
 	usb_acpi_unregister();
 	usb_debugfs_cleanup();
 	idr_destroy(&usb_bus_idr);

include/linux/usb.h

@@ -2035,8 +2035,16 @@ extern void usb_led_activity(enum usb_led_event ev);
 static inline void usb_led_activity(enum usb_led_event ev) {}
 #endif
 
-/* sysctl */
+/* sysctl.c */
 extern int deny_new_usb;
+#ifdef CONFIG_SYSCTL
+extern int usb_init_sysctl(void);
+extern void usb_exit_sysctl(void);
+#else
+static inline int usb_init_sysctl(void) { return 0; }
+static inline void usb_exit_sysctl(void) { }
+#endif /* CONFIG_SYSCTL */
+
 
 #endif  /* __KERNEL__ */
 

kernel/sysctl.c

@@ -2322,17 +2322,6 @@ static struct ctl_table kern_table[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
-#if IS_ENABLED(CONFIG_USB)
-	{
-		.procname	= "deny_new_usb",
-		.data		= &deny_new_usb,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax_sysadmin,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif
 	{
 		.procname	= "ngroups_max",
 		.data		= &ngroups_max,