Index: UPDATING
===================================================================
--- UPDATING
+++ UPDATING
@@ -26,6 +26,9 @@
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+2019xxxx:
+	Kernel-loadable random(4) modules are no longer unloadable.
+
 20191120:
 	The amd(8) automount daemon has been disabled by default, and will be
 	removed in the future.  As of FreeBSD 10.1 the autofs(5) is available
Index: sys/dev/random/random_harvestq.c
===================================================================
--- sys/dev/random/random_harvestq.c
+++ sys/dev/random/random_harvestq.c
@@ -49,11 +49,6 @@
 #include <sys/sysctl.h>
 #include <sys/unistd.h>
 
-#if defined(RANDOM_LOADABLE)
-#include <sys/lock.h>
-#include <sys/sx.h>
-#endif
-
 #include <machine/atomic.h>
 #include <machine/cpu.h>
 
@@ -164,13 +159,9 @@
 random_harvestq_fast_process_event(struct harvest_event *event)
 {
 #if defined(RANDOM_LOADABLE)
-	RANDOM_CONFIG_S_LOCK();
-	if (p_random_alg_context)
+	if (p_random_alg_context != NULL)
 #endif
 	p_random_alg_context->ra_event_processor(event);
-#if defined(RANDOM_LOADABLE)
-	RANDOM_CONFIG_S_UNLOCK();
-#endif
 	explicit_bzero(event, sizeof(*event));
 }
 
@@ -231,9 +222,8 @@
 	 * to the system-wide RNG.
 	 */
 #if defined(RANDOM_LOADABLE)
-	RANDOM_CONFIG_S_LOCK();
-	if (p_random_alg_context) {
-	/* It's an indenting error. Yeah, Yeah. */
+	if (p_random_alg_context == NULL)
+		return;
 #endif
 	local_read_rate = atomic_readandclear_32(&read_rate);
 	/* Perform at least one read per round */
@@ -261,10 +251,6 @@
 		}
 	}
 	explicit_bzero(entropy, sizeof(entropy));
-#if defined(RANDOM_LOADABLE)
-	}
-	RANDOM_CONFIG_S_UNLOCK();
-#endif
 }
 
 void
Index: sys/dev/random/random_infra.c
===================================================================
--- sys/dev/random/random_infra.c
+++ sys/dev/random/random_infra.c
@@ -35,11 +35,6 @@
 #include <sys/random.h>
 #include <sys/sysctl.h>
 
-#if defined(RANDOM_LOADABLE)
-#include <sys/lock.h>
-#include <sys/sx.h>
-#endif
-
 #include <dev/random/randomdev.h>
 
 /* Set up the sysctl root node for the entropy device */
@@ -121,87 +116,50 @@
 	return (false);
 }
 
-struct random_readers {
+static struct random_readers {
 	int	(*read_random_uio)(struct uio *, bool);
 	void	(*read_random)(void *, u_int);
 	bool	(*is_random_seeded)(void);
 } random_reader_context = {
-	(int (*)(struct uio *, bool))nullop,
+	(int (*)(struct uio *, bool))null_read_random,
 	null_read_random,
 	null_is_random_seeded,
 };
 
-struct sx randomdev_config_lock;
-
-static void
-random_infra_sysinit(void *dummy __unused)
-{
-
-	RANDOM_CONFIG_INIT_LOCK();
-}
-SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_FIRST, random_infra_sysinit, NULL);
-
 void
 random_infra_init(int (*p_random_read_uio)(struct uio *, bool),
     void (*p_random_read)(void *, u_int),
     bool (*p_is_random_seeded)(void))
 {
+#ifdef INVARIANTS
+	static bool loaded_once = false;
+
+	KASSERT(!loaded_once, ("%s: attempt to load a second randomdev module",
+	    __func__));
+	loaded_once  = true;
+#endif
 
-	RANDOM_CONFIG_X_LOCK();
 	random_reader_context.read_random_uio = p_random_read_uio;
 	random_reader_context.read_random = p_random_read;
 	random_reader_context.is_random_seeded = p_is_random_seeded;
-	RANDOM_CONFIG_X_UNLOCK();
-}
-
-void
-random_infra_uninit(void)
-{
-
-	RANDOM_CONFIG_X_LOCK();
-	random_reader_context.read_random_uio = (int (*)(struct uio *, bool))nullop;
-	random_reader_context.read_random = null_read_random;
-	random_reader_context.is_random_seeded = null_is_random_seeded;
-	RANDOM_CONFIG_X_UNLOCK();
-}
-
-static void
-random_infra_sysuninit(void *dummy __unused)
-{
-
-	RANDOM_CONFIG_DEINIT_LOCK();
 }
-SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_FIRST, random_infra_sysuninit, NULL);
 
 int
 read_random_uio(struct uio *uio, bool nonblock)
 {
-	int retval;
-
-	RANDOM_CONFIG_S_LOCK();
-	retval = random_reader_context.read_random_uio(uio, nonblock);
-	RANDOM_CONFIG_S_UNLOCK();
-	return (retval);
+	return (random_reader_context.read_random_uio(uio, nonblock));
 }
 
 void
 read_random(void *buf, u_int len)
 {
-
-	RANDOM_CONFIG_S_LOCK();
 	random_reader_context.read_random(buf, len);
-	RANDOM_CONFIG_S_UNLOCK();
 }
 
 bool
 is_random_seeded(void)
 {
-	bool result;
-
-	RANDOM_CONFIG_S_LOCK();
-	result = random_reader_context.is_random_seeded();
-	RANDOM_CONFIG_S_UNLOCK();
-	return (result);
+	return (random_reader_context.is_random_seeded());
 }
 
 
Index: sys/dev/random/randomdev.h
===================================================================
--- sys/dev/random/randomdev.h
+++ sys/dev/random/randomdev.h
@@ -106,16 +106,8 @@
 void random_source_deregister(struct random_source *);
 
 #if defined(RANDOM_LOADABLE)
-extern struct sx randomdev_config_lock;
-#define	RANDOM_CONFIG_INIT_LOCK(x)	sx_init(&randomdev_config_lock, "configuration change lock")
-#define	RANDOM_CONFIG_X_LOCK(x)		sx_xlock(&randomdev_config_lock)
-#define	RANDOM_CONFIG_X_UNLOCK(x)	sx_xunlock(&randomdev_config_lock)
-#define	RANDOM_CONFIG_S_LOCK(x)		sx_slock(&randomdev_config_lock)
-#define	RANDOM_CONFIG_S_UNLOCK(x)	sx_sunlock(&randomdev_config_lock)
-#define	RANDOM_CONFIG_DEINIT_LOCK(x)	sx_destroy(&randomdev_config_lock)
 void random_infra_init(int (*)(struct uio *, bool), void (*)(void *, u_int),
     bool (*)(void));
-void random_infra_uninit(void);
 #endif
 
 #endif /* _KERNEL */
Index: sys/dev/random/randomdev.c
===================================================================
--- sys/dev/random/randomdev.c
+++ sys/dev/random/randomdev.c
@@ -104,9 +104,6 @@
 random_alg_context_ra_deinit_alg(void *data)
 {
 
-#if defined(RANDOM_LOADABLE)
-	random_infra_uninit();
-#endif
 	p_random_alg_context->ra_deinit_alg(data);
 	p_random_alg_context = NULL;
 }
@@ -424,7 +421,7 @@
 		make_dev_alias(random_dev, "urandom"); /* compatibility */
 		break;
 	case MOD_UNLOAD:
-		destroy_dev(random_dev);
+		error = EBUSY;
 		break;
 	case MOD_SHUTDOWN:
 		break;