1 files changed, 189 insertions, 182 deletions

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index eddae4688862..bec2af11853a 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -10,9 +10,6 @@
 #include <linux/if_xdp.h>
 #include <net/xdp_sock.h>
 
-#define RX_BATCH_SIZE 16
-#define LAZY_UPDATE_THRESHOLD 128
-
 struct xdp_ring {
 	u32 producer ____cacheline_aligned_in_smp;
 	u32 consumer ____cacheline_aligned_in_smp;
@@ -36,10 +33,8 @@ struct xsk_queue {
 	u64 size;
 	u32 ring_mask;
 	u32 nentries;
-	u32 prod_head;
-	u32 prod_tail;
-	u32 cons_head;
-	u32 cons_tail;
+	u32 cached_prod;
+	u32 cached_cons;
 	struct xdp_ring *ring;
 	u64 invalid_descs;
 };
@@ -86,56 +81,31 @@ struct xsk_queue {
  * now and again after circling through the ring.
  */
 
-/* Common functions operating for both RXTX and umem queues */
-
-static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
-{
-	return q ? q->invalid_descs : 0;
-}
-
-static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
-{
-	u32 entries = q->prod_tail - q->cons_tail;
-
-	if (entries == 0) {
-		/* Refresh the local pointer */
-		q->prod_tail = READ_ONCE(q->ring->producer);
-		entries = q->prod_tail - q->cons_tail;
-	}
-
-	return (entries > dcnt) ? dcnt : entries;
-}
-
-static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
-{
-	u32 free_entries = q->nentries - (producer - q->cons_tail);
-
-	if (free_entries >= dcnt)
-		return free_entries;
-
-	/* Refresh the local tail pointer */
-	q->cons_tail = READ_ONCE(q->ring->consumer);
-	return q->nentries - (producer - q->cons_tail);
-}
-
-static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
-{
-	u32 entries = q->prod_tail - q->cons_tail;
-
-	if (entries >= cnt)
-		return true;
-
-	/* Refresh the local pointer. */
-	q->prod_tail = READ_ONCE(q->ring->producer);
-	entries = q->prod_tail - q->cons_tail;
-
-	return entries >= cnt;
-}
+/* The operations on the rings are the following:
+ *
+ * producer                           consumer
+ *
+ * RESERVE entries                    PEEK in the ring for entries
+ * WRITE data into the ring           READ data from the ring
+ * SUBMIT entries                     RELEASE entries
+ *
+ * The producer reserves one or more entries in the ring. It can then
+ * fill in these entries and finally submit them so that they can be
+ * seen and read by the consumer.
+ *
+ * The consumer peeks into the ring to see if the producer has written
+ * any new entries. If so, the producer can then read these entries
+ * and when it is done reading them release them back to the producer
+ * so that the producer can use these slots to fill in new entries.
+ *
+ * The function names below reflect these operations.
+ */
 
-/* UMEM queue */
+/* Functions that read and validate content from consumer rings. */
 
-static inline bool xskq_crosses_non_contig_pg(struct xdp_umem *umem, u64 addr,
-					      u64 length)
+static inline bool xskq_cons_crosses_non_contig_pg(struct xdp_umem *umem,
+						   u64 addr,
+						   u64 length)
 {
 	bool cross_pg = (addr & (PAGE_SIZE - 1)) + length > PAGE_SIZE;
 	bool next_pg_contig =
@@ -145,9 +115,16 @@ static inline bool xskq_crosses_non_contig_pg(struct xdp_umem *umem, u64 addr,
 	return cross_pg && !next_pg_contig;
 }
 
-static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
+static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
+						u64 addr,
+						u64 length,
+						struct xdp_umem *umem)
 {
-	if (addr >= q->size) {
+	u64 base_addr = xsk_umem_extract_addr(addr);
+
+	addr = xsk_umem_add_offset_to_addr(addr);
+	if (base_addr >= q->size || addr >= q->size ||
+	    xskq_cons_crosses_non_contig_pg(umem, addr, length)) {
 		q->invalid_descs++;
 		return false;
 	}
@@ -155,15 +132,9 @@ static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
 	return true;
 }
 
-static inline bool xskq_is_valid_addr_unaligned(struct xsk_queue *q, u64 addr,
-						u64 length,
-						struct xdp_umem *umem)
+static inline bool xskq_cons_is_valid_addr(struct xsk_queue *q, u64 addr)
 {
-	u64 base_addr = xsk_umem_extract_addr(addr);
-
-	addr = xsk_umem_add_offset_to_addr(addr);
-	if (base_addr >= q->size || addr >= q->size ||
-	    xskq_crosses_non_contig_pg(umem, addr, length)) {
+	if (addr >= q->size) {
 		q->invalid_descs++;
 		return false;
 	}
@@ -171,204 +142,240 @@ static inline bool xskq_is_valid_addr_unaligned(struct xsk_queue *q, u64 addr,
 	return true;
 }
 
-static inline u64 *xskq_validate_addr(struct xsk_queue *q, u64 *addr,
-				      struct xdp_umem *umem)
+static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
+				       struct xdp_umem *umem)
 {
-	while (q->cons_tail != q->cons_head) {
-		struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
-		unsigned int idx = q->cons_tail & q->ring_mask;
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-		*addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
+	while (q->cached_cons != q->cached_prod) {
+		u32 idx = q->cached_cons & q->ring_mask;
+
+		*addr = ring->desc[idx] & q->chunk_mask;
 
 		if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
-			if (xskq_is_valid_addr_unaligned(q, *addr,
+			if (xskq_cons_is_valid_unaligned(q, *addr,
 							 umem->chunk_size_nohr,
 							 umem))
-				return addr;
+				return true;
 			goto out;
 		}
 
-		if (xskq_is_valid_addr(q, *addr))
-			return addr;
+		if (xskq_cons_is_valid_addr(q, *addr))
+			return true;
 
 out:
-		q->cons_tail++;
+		q->cached_cons++;
 	}
 
-	return NULL;
+	return false;
 }
 
-static inline u64 *xskq_peek_addr(struct xsk_queue *q, u64 *addr,
-				  struct xdp_umem *umem)
+static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
+					   struct xdp_desc *d,
+					   struct xdp_umem *umem)
 {
-	if (q->cons_tail == q->cons_head) {
-		smp_mb(); /* D, matches A */
-		WRITE_ONCE(q->ring->consumer, q->cons_tail);
-		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
+	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
+		if (!xskq_cons_is_valid_unaligned(q, d->addr, d->len, umem))
+			return false;
+
+		if (d->len > umem->chunk_size_nohr || d->options) {
+			q->invalid_descs++;
+			return false;
+		}
 
-		/* Order consumer and data */
-		smp_rmb();
+		return true;
 	}
 
-	return xskq_validate_addr(q, addr, umem);
-}
+	if (!xskq_cons_is_valid_addr(q, d->addr))
+		return false;
 
-static inline void xskq_discard_addr(struct xsk_queue *q)
-{
-	q->cons_tail++;
+	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
+	    d->options) {
+		q->invalid_descs++;
+		return false;
+	}
+
+	return true;
 }
 
-static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
+static inline bool xskq_cons_read_desc(struct xsk_queue *q,
+				       struct xdp_desc *desc,
+				       struct xdp_umem *umem)
 {
-	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
-
-	if (xskq_nb_free(q, q->prod_tail, 1) == 0)
-		return -ENOSPC;
+	while (q->cached_cons != q->cached_prod) {
+		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
+		u32 idx = q->cached_cons & q->ring_mask;
 
-	/* A, matches D */
-	ring->desc[q->prod_tail++ & q->ring_mask] = addr;
+		*desc = ring->desc[idx];
+		if (xskq_cons_is_valid_desc(q, desc, umem))
+			return true;
 
-	/* Order producer and data */
-	smp_wmb(); /* B, matches C */
+		q->cached_cons++;
+	}
 
-	WRITE_ONCE(q->ring->producer, q->prod_tail);
-	return 0;
+	return false;
 }
 
-static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
+/* Functions for consumers */
+
+static inline void __xskq_cons_release(struct xsk_queue *q)
 {
-	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+	smp_mb(); /* D, matches A */
+	WRITE_ONCE(q->ring->consumer, q->cached_cons);
+}
 
-	if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
-		return -ENOSPC;
+static inline void __xskq_cons_peek(struct xsk_queue *q)
+{
+	/* Refresh the local pointer */
+	q->cached_prod = READ_ONCE(q->ring->producer);
+	smp_rmb(); /* C, matches B */
+}
 
-	/* A, matches D */
-	ring->desc[q->prod_head++ & q->ring_mask] = addr;
-	return 0;
+static inline void xskq_cons_get_entries(struct xsk_queue *q)
+{
+	__xskq_cons_release(q);
+	__xskq_cons_peek(q);
 }
 
-static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
-					     u32 nb_entries)
+static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
 {
-	/* Order producer and data */
-	smp_wmb(); /* B, matches C */
+	u32 entries = q->cached_prod - q->cached_cons;
 
-	q->prod_tail += nb_entries;
-	WRITE_ONCE(q->ring->producer, q->prod_tail);
+	if (entries >= cnt)
+		return true;
+
+	__xskq_cons_peek(q);
+	entries = q->cached_prod - q->cached_cons;
+
+	return entries >= cnt;
 }
 
-static inline int xskq_reserve_addr(struct xsk_queue *q)
+static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
+				       struct xdp_umem *umem)
 {
-	if (xskq_nb_free(q, q->prod_head, 1) == 0)
-		return -ENOSPC;
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
+	return xskq_cons_read_addr(q, addr, umem);
+}
 
-	/* A, matches D */
-	q->prod_head++;
-	return 0;
+static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
+				       struct xdp_desc *desc,
+				       struct xdp_umem *umem)
+{
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
+	return xskq_cons_read_desc(q, desc, umem);
 }
 
-/* Rx/Tx queue */
+static inline void xskq_cons_release(struct xsk_queue *q)
+{
+	/* To improve performance, only update local state here.
+	 * Reflect this to global state when we get new entries
+	 * from the ring in xskq_cons_get_entries().
+	 */
+	q->cached_cons++;
+}
 
-static inline bool xskq_is_valid_desc(struct xsk_queue *q, struct xdp_desc *d,
-				      struct xdp_umem *umem)
+static inline bool xskq_cons_is_full(struct xsk_queue *q)
 {
-	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
-		if (!xskq_is_valid_addr_unaligned(q, d->addr, d->len, umem))
-			return false;
+	/* No barriers needed since data is not accessed */
+	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
+		q->nentries;
+}
 
-		if (d->len > umem->chunk_size_nohr || d->options) {
-			q->invalid_descs++;
-			return false;
-		}
+/* Functions for producers */
 
-		return true;
-	}
+static inline bool xskq_prod_is_full(struct xsk_queue *q)
+{
+	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);
 
-	if (!xskq_is_valid_addr(q, d->addr))
+	if (free_entries)
 		return false;
 
-	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
-	    d->options) {
-		q->invalid_descs++;
-		return false;
-	}
+	/* Refresh the local tail pointer */
+	q->cached_cons = READ_ONCE(q->ring->consumer);
+	free_entries = q->nentries - (q->cached_prod - q->cached_cons);
 
-	return true;
+	return !free_entries;
 }
 
-static inline struct xdp_desc *xskq_validate_desc(struct xsk_queue *q,
-						  struct xdp_desc *desc,
-						  struct xdp_umem *umem)
+static inline int xskq_prod_reserve(struct xsk_queue *q)
 {
-	while (q->cons_tail != q->cons_head) {
-		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
-		unsigned int idx = q->cons_tail & q->ring_mask;
-
-		*desc = READ_ONCE(ring->desc[idx]);
-		if (xskq_is_valid_desc(q, desc, umem))
-			return desc;
-
-		q->cons_tail++;
-	}
+	if (xskq_prod_is_full(q))
+		return -ENOSPC;
 
-	return NULL;
+	/* A, matches D */
+	q->cached_prod++;
+	return 0;
 }
 
-static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
-					      struct xdp_desc *desc,
-					      struct xdp_umem *umem)
+static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
 {
-	if (q->cons_tail == q->cons_head) {
-		smp_mb(); /* D, matches A */
-		WRITE_ONCE(q->ring->consumer, q->cons_tail);
-		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
-
-		/* Order consumer and data */
-		smp_rmb(); /* C, matches B */
-	}
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-	return xskq_validate_desc(q, desc, umem);
-}
+	if (xskq_prod_is_full(q))
+		return -ENOSPC;
 
-static inline void xskq_discard_desc(struct xsk_queue *q)
-{
-	q->cons_tail++;
+	/* A, matches D */
+	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
+	return 0;
 }
 
-static inline int xskq_produce_batch_desc(struct xsk_queue *q,
-					  u64 addr, u32 len)
+static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
+					 u64 addr, u32 len)
 {
 	struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
-	unsigned int idx;
+	u32 idx;
 
-	if (xskq_nb_free(q, q->prod_head, 1) == 0)
+	if (xskq_prod_is_full(q))
 		return -ENOSPC;
 
 	/* A, matches D */
-	idx = (q->prod_head++) & q->ring_mask;
+	idx = q->cached_prod++ & q->ring_mask;
 	ring->desc[idx].addr = addr;
 	ring->desc[idx].len = len;
 
 	return 0;
 }
 
-static inline void xskq_produce_flush_desc(struct xsk_queue *q)
+static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
 {
-	/* Order producer and data */
 	smp_wmb(); /* B, matches C */
 
-	q->prod_tail = q->prod_head;
-	WRITE_ONCE(q->ring->producer, q->prod_tail);
+	WRITE_ONCE(q->ring->producer, idx);
+}
+
+static inline void xskq_prod_submit(struct xsk_queue *q)
+{
+	__xskq_prod_submit(q, q->cached_prod);
+}
+
+static inline void xskq_prod_submit_addr(struct xsk_queue *q, u64 addr)
+{
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+	u32 idx = q->ring->producer;
+
+	ring->desc[idx++ & q->ring_mask] = addr;
+
+	__xskq_prod_submit(q, idx);
 }
 
-static inline bool xskq_full_desc(struct xsk_queue *q)
+static inline void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
 {
-	return xskq_nb_avail(q, q->nentries) == q->nentries;
+	__xskq_prod_submit(q, q->ring->producer + nb_entries);
 }
 
-static inline bool xskq_empty_desc(struct xsk_queue *q)
+static inline bool xskq_prod_is_empty(struct xsk_queue *q)
 {
-	return xskq_nb_free(q, q->prod_tail, q->nentries) == q->nentries;
+	/* No barriers needed since data is not accessed */
+	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);
+}
+
+/* For both producers and consumers */
+
+static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
+{
+	return q ? q->invalid_descs : 0;
 }
 
 void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);