D5416.id54425.diff
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	Index: head/sys/net/ifq.h
	===================================================================
	--- head/sys/net/ifq.h
	+++ head/sys/net/ifq.h
	@@ -369,7 +369,7 @@
	return (m);
	}
	#endif
	- return(buf_ring_peek(br));
	+ return(buf_ring_peek_clear_sc(br));
	}

	static __inline void
	Index: head/sys/sys/buf_ring.h
	===================================================================
	--- head/sys/sys/buf_ring.h
	+++ head/sys/sys/buf_ring.h
	@@ -268,6 +268,37 @@
	return (br->br_ring[br->br_cons_head]);
	}

	+static __inline void *
	+buf_ring_peek_clear_sc(struct buf_ring *br)
	+{
	+#ifdef DEBUG_BUFRING
	+ void *ret;
	+
	+ if (!mtx_owned(br->br_lock))
	+ panic("lock not held on single consumer dequeue");
	+#endif
	+ /*
	+ * I believe it is safe to not have a memory barrier
	+ * here because we control cons and tail is worst case
	+ * a lagging indicator so we worst case we might
	+ * return NULL immediately after a buffer has been enqueued
	+ */
	+ if (br->br_cons_head == br->br_prod_tail)
	+ return (NULL);
	+
	+#ifdef DEBUG_BUFRING
	+ /*
	+ * Single consumer, i.e. cons_head will not move while we are
	+ * running, so atomic_swap_ptr() is not necessary here.
	+ */
	+ ret = br->br_ring[br->br_cons_head];
	+ br->br_ring[br->br_cons_head] = NULL;
	+ return (ret);
	+#else
	+ return (br->br_ring[br->br_cons_head]);
	+#endif
	+}
	+
	static __inline int
	buf_ring_full(struct buf_ring *br)
	{