Index: sys/dev/random/random_harvestq.h
===================================================================
--- sys/dev/random/random_harvestq.h
+++ sys/dev/random/random_harvestq.h
@@ -47,6 +47,7 @@
 
 #define	RANDOM_HARVEST_INIT_LOCK(x)	mtx_init(&harvest_context.hc_mtx, "entropy harvest mutex", NULL, MTX_SPIN)
 #define	RANDOM_HARVEST_LOCK(x)		mtx_lock_spin(&harvest_context.hc_mtx)
+#define	RANDOM_HARVEST_TRYLOCK(x)	mtx_trylock_spin(&harvest_context.hc_mtx)
 #define	RANDOM_HARVEST_UNLOCK(x)	mtx_unlock_spin(&harvest_context.hc_mtx)
 
 #endif /* SYS_DEV_RANDOM_RANDOM_HARVESTQ_H_INCLUDED */
Index: sys/dev/random/random_harvestq.c
===================================================================
--- sys/dev/random/random_harvestq.c
+++ sys/dev/random/random_harvestq.c
@@ -425,7 +425,10 @@
 	KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin));
 	if (!(harvest_context.hc_source_mask & (1 << origin)))
 		return;
-	RANDOM_HARVEST_LOCK();
+	if (!RANDOM_HARVEST_TRYLOCK()) {
+		random_harvest_fast(entropy, size, bits, origin);
+		return;
+	}
 	ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX;
 	if (ring_in != harvest_context.hc_entropy_ring.out) {
 		/* The ring is not full */