D6986.id17924.diff
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	Index: sys/sys/buf_ring.h
	===================================================================
	--- sys/sys/buf_ring.h
	+++ sys/sys/buf_ring.h
	@@ -162,8 +162,34 @@
	uint32_t prod_tail;
	void *buf;

	+ /*
	+ * This is a workaround to allow using buf_ring on ARM and ARM64.
	+ * ARM64TODO: Fix buf_ring in a generic way.
	+ *
	+ * Preventing following situation:
	+
	+ * Core(0) - buf_ring_enqueue() Core(1) - buf_ring_dequeue_sc()
	+ * ----------------------------------------- ----------------------------------------------
	+ *
	+ * cons_head = br->br_cons_head;
	+ * atomic_cmpset_acq_32(&br->br_prod_head, ...));
	+ * buf = br->br_ring[cons_head]; <see <1>>
	+ * br->br_ring[prod_head] = buf;
	+ * atomic_store_rel_32(&br->br_prod_tail, ...);
	+ * prod_tail = br->br_prod_tail;
	+ * if (cons_head == prod_tail)
	+ * return (NULL);
	+ * <condition is false and code uses invalid(old) buf>`
	+ *
	+ * <1> Load (on core 1) from br->br_ring[cons_head] can be reordered (speculative readed) by CPU.
	+ */
	+#if defined(__arm__) \|\| defined(__aarch64__)
	+ cons_head = atomic_load_acq_32(&br->br_cons_head);
	+ prod_tail = atomic_load_acq_32(&br->br_prod_tail);
	+#else
	cons_head = br->br_cons_head;
	prod_tail = br->br_prod_tail;
	+#endif

	cons_next = (cons_head + 1) & br->br_cons_mask;
	#ifdef PREFETCH_DEFINED