From 484b165306e18fd9a0d960e6ed2d6eff31665522 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:20 +0100
Subject: xsk: Eliminate the lazy update threshold

The lazy update threshold was introduced to keep the producer and
consumer some distance apart in the completion ring. This was
important in the beginning of the development of AF_XDP as the ring
format as that point in time was very sensitive to the producer and
consumer being on the same cache line. This is not the case
anymore as the current ring format does not degrade in any noticeable
way when this happens. Moreover, this threshold makes it impossible
to run the system with rings that have less than 128 entries.

So let us remove this threshold and just get one entry from the ring
as in all other functions. This will enable us to remove this function
in a later commit. Note that xskq_produce_addr_lazy followed by
xskq_produce_flush_addr_n are still not the same function as
xskq_produce_addr() as it operates on another cached pointer.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-2-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index eddae4688862..a2f0ba65559f 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -11,7 +11,6 @@
 #include <net/xdp_sock.h>
 
 #define RX_BATCH_SIZE 16
-#define LAZY_UPDATE_THRESHOLD 128
 
 struct xdp_ring {
 	u32 producer ____cacheline_aligned_in_smp;
@@ -239,7 +238,7 @@ static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-	if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
+	if (xskq_nb_free(q, q->prod_head, 1) == 0)
 		return -ENOSPC;
 
 	/* A, matches D */
-- 
cgit v1.2.3-59-g8ed1b


From 11cc2d21499cabe7e7964389634ed1de3ee91d33 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:21 +0100
Subject: xsk: Simplify detection of empty and full rings

In order to set the correct return flags for poll, the xsk code has to
check if the Rx queue is empty and if the Tx queue is full. This code
was unnecessarily large and complex as it used the functions that are
used to update the local state from the global state (xskq_nb_free and
xskq_nb_avail). Since we are not doing this nor updating any data
dependent on this state, we can simplify the functions. Another
benefit from this is that we can also simplify the xskq_nb_free and
xskq_nb_avail functions in a later commit.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-3-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index a2f0ba65559f..b28f9da7b317 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -362,12 +362,15 @@ static inline void xskq_produce_flush_desc(struct xsk_queue *q)
 
 static inline bool xskq_full_desc(struct xsk_queue *q)
 {
-	return xskq_nb_avail(q, q->nentries) == q->nentries;
+	/* No barriers needed since data is not accessed */
+	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
+		q->nentries;
 }
 
 static inline bool xskq_empty_desc(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);
 }
 
 void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask);
-- 
cgit v1.2.3-59-g8ed1b


From d7012f05e3ca5aba92770c370895092d4882e8c2 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:22 +0100
Subject: xsk: Consolidate to one single cached producer pointer

Currently, the xsk ring code has two cached producer pointers:
prod_head and prod_tail. This patch consolidates these two into a
single one called cached_prod to make the code simpler and easier to
maintain. This will be in line with the user space part of the the
code found in libbpf, that only uses a single cached pointer.

The Rx path only uses the two top level functions
xskq_produce_batch_desc and xskq_produce_flush_desc and they both use
prod_head and never prod_tail. So just move them over to
cached_prod.

The Tx XDP_DRV path uses xskq_produce_addr_lazy and
xskq_produce_flush_addr_n and unnecessarily operates on both prod_tail
and prod_head, so move them over to just use cached_prod by skipping
the intermediate step of updating prod_tail.

The Tx path in XDP_SKB mode uses xskq_reserve_addr and
xskq_produce_addr. They currently use both cached pointers, but we can
operate on the global producer pointer in xskq_produce_addr since it
has to be updated anyway, thus eliminating the use of both cached
pointers. We can also remove the xskq_nb_free in xskq_produce_addr
since it is already called in xskq_reserve_addr. No need to do it
twice.

When there is only one cached producer pointer, we can also simplify
xskq_nb_free by removing one argument.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-4-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 47 +++++++++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 26 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index b28f9da7b317..7ad80748f209 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -35,8 +35,7 @@ struct xsk_queue {
 	u64 size;
 	u32 ring_mask;
 	u32 nentries;
-	u32 prod_head;
-	u32 prod_tail;
+	u32 cached_prod;
 	u32 cons_head;
 	u32 cons_tail;
 	struct xdp_ring *ring;
@@ -94,39 +93,39 @@ static inline u64 xskq_nb_invalid_descs(struct xsk_queue *q)
 
 static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
 {
-	u32 entries = q->prod_tail - q->cons_tail;
+	u32 entries = q->cached_prod - 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;
+		q->cached_prod = READ_ONCE(q->ring->producer);
+		entries = q->cached_prod - q->cons_tail;
 	}
 
 	return (entries > dcnt) ? dcnt : entries;
 }
 
-static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
+static inline u32 xskq_nb_free(struct xsk_queue *q, u32 dcnt)
 {
-	u32 free_entries = q->nentries - (producer - q->cons_tail);
+	u32 free_entries = q->nentries - (q->cached_prod - 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);
+	return q->nentries - (q->cached_prod - q->cons_tail);
 }
 
 static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
 {
-	u32 entries = q->prod_tail - q->cons_tail;
+	u32 entries = q->cached_prod - 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;
+	q->cached_prod = READ_ONCE(q->ring->producer);
+	entries = q->cached_prod - q->cons_tail;
 
 	return entries >= cnt;
 }
@@ -220,17 +219,15 @@ static inline void xskq_discard_addr(struct xsk_queue *q)
 static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
-
-	if (xskq_nb_free(q, q->prod_tail, 1) == 0)
-		return -ENOSPC;
+	unsigned int idx = q->ring->producer;
 
 	/* A, matches D */
-	ring->desc[q->prod_tail++ & q->ring_mask] = addr;
+	ring->desc[idx++ & q->ring_mask] = addr;
 
 	/* Order producer and data */
 	smp_wmb(); /* B, matches C */
 
-	WRITE_ONCE(q->ring->producer, q->prod_tail);
+	WRITE_ONCE(q->ring->producer, idx);
 	return 0;
 }
 
@@ -238,11 +235,11 @@ static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-	if (xskq_nb_free(q, q->prod_head, 1) == 0)
+	if (xskq_nb_free(q, 1) == 0)
 		return -ENOSPC;
 
 	/* A, matches D */
-	ring->desc[q->prod_head++ & q->ring_mask] = addr;
+	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
 	return 0;
 }
 
@@ -252,17 +249,16 @@ static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
 	/* Order producer and data */
 	smp_wmb(); /* B, matches C */
 
-	q->prod_tail += nb_entries;
-	WRITE_ONCE(q->ring->producer, q->prod_tail);
+	WRITE_ONCE(q->ring->producer, q->ring->producer + nb_entries);
 }
 
 static inline int xskq_reserve_addr(struct xsk_queue *q)
 {
-	if (xskq_nb_free(q, q->prod_head, 1) == 0)
+	if (xskq_nb_free(q, 1) == 0)
 		return -ENOSPC;
 
 	/* A, matches D */
-	q->prod_head++;
+	q->cached_prod++;
 	return 0;
 }
 
@@ -340,11 +336,11 @@ static inline int xskq_produce_batch_desc(struct xsk_queue *q,
 	struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
 	unsigned int idx;
 
-	if (xskq_nb_free(q, q->prod_head, 1) == 0)
+	if (xskq_nb_free(q, 1) == 0)
 		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;
 
@@ -356,8 +352,7 @@ static inline void xskq_produce_flush_desc(struct xsk_queue *q)
 	/* 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, q->cached_prod);
 }
 
 static inline bool xskq_full_desc(struct xsk_queue *q)
-- 
cgit v1.2.3-59-g8ed1b


From 59e35e552529b858f35b30bc5a803ea532ca17f1 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:23 +0100
Subject: xsk: Standardize naming of producer ring access functions

Adopt the naming of the producer ring access functions to have a
similar naming convention as the functions in libbpf, but adapted to
the kernel. You first reserve a number of entries that you later
submit to the global state of the ring. This is much clearer, IMO,
than the one that was in the kernel part. Once renamed, we also
discover that two functions are actually the same, so remove one of
them. Some of the primitive ring submission operations are also the
same so break these out into __xskq_prod_submit that the upper level
ring access functions can use.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-5-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk.c       | 20 +++++++++---------
 net/xdp/xsk_queue.h | 58 +++++++++++++++++++++++++----------------------------
 2 files changed, 37 insertions(+), 41 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index e45c27f5cfca..5f2123fe630c 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -167,7 +167,7 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 
 	offset += metalen;
 	addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
-	err = xskq_produce_batch_desc(xs->rx, addr, len);
+	err = xskq_prod_reserve_desc(xs->rx, addr, len);
 	if (!err) {
 		xskq_discard_addr(xs->umem->fq);
 		xdp_return_buff(xdp);
@@ -180,7 +180,7 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 
 static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 {
-	int err = xskq_produce_batch_desc(xs->rx, (u64)xdp->handle, len);
+	int err = xskq_prod_reserve_desc(xs->rx, xdp->handle, len);
 
 	if (err)
 		xs->rx_dropped++;
@@ -216,7 +216,7 @@ static int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 
 static void xsk_flush(struct xdp_sock *xs)
 {
-	xskq_produce_flush_desc(xs->rx);
+	xskq_prod_submit(xs->rx);
 	xs->sk.sk_data_ready(&xs->sk);
 }
 
@@ -247,12 +247,12 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 	memcpy(buffer, xdp->data_meta, len + metalen);
 
 	addr = xsk_umem_adjust_offset(xs->umem, addr, metalen);
-	err = xskq_produce_batch_desc(xs->rx, addr, len);
+	err = xskq_prod_reserve_desc(xs->rx, addr, len);
 	if (err)
 		goto out_drop;
 
 	xskq_discard_addr(xs->umem->fq);
-	xskq_produce_flush_desc(xs->rx);
+	xskq_prod_submit(xs->rx);
 
 	spin_unlock_bh(&xs->rx_lock);
 
@@ -294,7 +294,7 @@ void __xsk_map_flush(void)
 
 void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries)
 {
-	xskq_produce_flush_addr_n(umem->cq, nb_entries);
+	xskq_prod_submit_n(umem->cq, nb_entries);
 }
 EXPORT_SYMBOL(xsk_umem_complete_tx);
 
@@ -319,7 +319,7 @@ bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc)
 		if (!xskq_peek_desc(xs->tx, desc, umem))
 			continue;
 
-		if (xskq_produce_addr_lazy(umem->cq, desc->addr))
+		if (xskq_prod_reserve_addr(umem->cq, desc->addr))
 			goto out;
 
 		xskq_discard_desc(xs->tx);
@@ -348,7 +348,7 @@ static void xsk_destruct_skb(struct sk_buff *skb)
 	unsigned long flags;
 
 	spin_lock_irqsave(&xs->tx_completion_lock, flags);
-	WARN_ON_ONCE(xskq_produce_addr(xs->umem->cq, addr));
+	xskq_prod_submit_addr(xs->umem->cq, addr);
 	spin_unlock_irqrestore(&xs->tx_completion_lock, flags);
 
 	sock_wfree(skb);
@@ -389,7 +389,7 @@ static int xsk_generic_xmit(struct sock *sk)
 		addr = desc.addr;
 		buffer = xdp_umem_get_data(xs->umem, addr);
 		err = skb_store_bits(skb, 0, buffer, len);
-		if (unlikely(err) || xskq_reserve_addr(xs->umem->cq)) {
+		if (unlikely(err) || xskq_prod_reserve(xs->umem->cq)) {
 			kfree_skb(skb);
 			goto out;
 		}
@@ -470,7 +470,7 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
 			__xsk_sendmsg(sk);
 	}
 
-	if (xs->rx && !xskq_empty_desc(xs->rx))
+	if (xs->rx && !xskq_prod_is_empty(xs->rx))
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (xs->tx && !xskq_full_desc(xs->tx))
 		mask |= EPOLLOUT | EPOLLWRNORM;
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 7ad80748f209..1b9a350f2e66 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -216,22 +216,17 @@ static inline void xskq_discard_addr(struct xsk_queue *q)
 	q->cons_tail++;
 }
 
-static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
+static inline int xskq_prod_reserve(struct xsk_queue *q)
 {
-	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
-	unsigned int idx = q->ring->producer;
+	if (xskq_nb_free(q, 1) == 0)
+		return -ENOSPC;
 
 	/* A, matches D */
-	ring->desc[idx++ & q->ring_mask] = addr;
-
-	/* Order producer and data */
-	smp_wmb(); /* B, matches C */
-
-	WRITE_ONCE(q->ring->producer, idx);
+	q->cached_prod++;
 	return 0;
 }
 
-static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
+static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
@@ -243,23 +238,32 @@ static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
 	return 0;
 }
 
-static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
-					     u32 nb_entries)
+static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
 {
 	/* Order producer and data */
 	smp_wmb(); /* B, matches C */
 
-	WRITE_ONCE(q->ring->producer, q->ring->producer + nb_entries);
+	WRITE_ONCE(q->ring->producer, idx);
 }
 
-static inline int xskq_reserve_addr(struct xsk_queue *q)
+static inline void xskq_prod_submit(struct xsk_queue *q)
 {
-	if (xskq_nb_free(q, 1) == 0)
-		return -ENOSPC;
+	__xskq_prod_submit(q, q->cached_prod);
+}
 
-	/* A, matches D */
-	q->cached_prod++;
-	return 0;
+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 void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
+{
+	__xskq_prod_submit(q, q->ring->producer + nb_entries);
 }
 
 /* Rx/Tx queue */
@@ -330,11 +334,11 @@ static inline void xskq_discard_desc(struct xsk_queue *q)
 	q->cons_tail++;
 }
 
-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, 1) == 0)
 		return -ENOSPC;
@@ -347,14 +351,6 @@ static inline int xskq_produce_batch_desc(struct xsk_queue *q,
 	return 0;
 }
 
-static inline void xskq_produce_flush_desc(struct xsk_queue *q)
-{
-	/* Order producer and data */
-	smp_wmb(); /* B, matches C */
-
-	WRITE_ONCE(q->ring->producer, q->cached_prod);
-}
-
 static inline bool xskq_full_desc(struct xsk_queue *q)
 {
 	/* No barriers needed since data is not accessed */
@@ -362,7 +358,7 @@ static inline bool xskq_full_desc(struct xsk_queue *q)
 		q->nentries;
 }
 
-static inline bool xskq_empty_desc(struct xsk_queue *q)
+static inline bool xskq_prod_is_empty(struct xsk_queue *q)
 {
 	/* No barriers needed since data is not accessed */
 	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);
-- 
cgit v1.2.3-59-g8ed1b


From 4b638f13bab4dbfe8569c84e374e8201a427115c Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:24 +0100
Subject: xsk: Eliminate the RX batch size

In the xsk consumer ring code there is a variable called RX_BATCH_SIZE
that dictates the minimum number of entries that we try to grab from
the fill and Tx rings. In fact, the code always try to grab the
maximum amount of entries from these rings. The only thing this
variable does is to throw an error if there is less than 16 (as it is
defined) entries on the ring. There is no reason to do this and it
will just lead to weird behavior from user space's point of view. So
eliminate this variable.

With this change, we will be able to simplify the xskq_nb_free and
xskq_nb_avail code in the next commit.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-6-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 1b9a350f2e66..6ca5fed87852 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -10,8 +10,6 @@
 #include <linux/if_xdp.h>
 #include <net/xdp_sock.h>
 
-#define RX_BATCH_SIZE 16
-
 struct xdp_ring {
 	u32 producer ____cacheline_aligned_in_smp;
 	u32 consumer ____cacheline_aligned_in_smp;
@@ -202,7 +200,7 @@ static inline u64 *xskq_peek_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);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q, 1);
 
 		/* Order consumer and data */
 		smp_rmb();
@@ -320,7 +318,7 @@ static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
 	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);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q, 1);
 
 		/* Order consumer and data */
 		smp_rmb(); /* C, matches B */
-- 
cgit v1.2.3-59-g8ed1b


From df0ae6f78a45e5696427779fc3379c5d75f5d4a5 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:25 +0100
Subject: xsk: Simplify xskq_nb_avail and xskq_nb_free

At this point, there are no users of the functions xskq_nb_avail and
xskq_nb_free that take any other number of entries argument than 1, so
let us get rid of the second argument that takes the number of
entries.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-7-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 6ca5fed87852..8bfa2ee6864c 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -89,7 +89,7 @@ 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)
+static inline u32 xskq_nb_avail(struct xsk_queue *q)
 {
 	u32 entries = q->cached_prod - q->cons_tail;
 
@@ -99,19 +99,21 @@ static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
 		entries = q->cached_prod - q->cons_tail;
 	}
 
-	return (entries > dcnt) ? dcnt : entries;
+	return entries;
 }
 
-static inline u32 xskq_nb_free(struct xsk_queue *q, u32 dcnt)
+static inline bool xskq_prod_is_full(struct xsk_queue *q)
 {
 	u32 free_entries = q->nentries - (q->cached_prod - q->cons_tail);
 
-	if (free_entries >= dcnt)
-		return free_entries;
+	if (free_entries)
+		return false;
 
 	/* Refresh the local tail pointer */
 	q->cons_tail = READ_ONCE(q->ring->consumer);
-	return q->nentries - (q->cached_prod - q->cons_tail);
+	free_entries = q->nentries - (q->cached_prod - q->cons_tail);
+
+	return !free_entries;
 }
 
 static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
@@ -200,7 +202,7 @@ static inline u64 *xskq_peek_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, 1);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q);
 
 		/* Order consumer and data */
 		smp_rmb();
@@ -216,7 +218,7 @@ static inline void xskq_discard_addr(struct xsk_queue *q)
 
 static inline int xskq_prod_reserve(struct xsk_queue *q)
 {
-	if (xskq_nb_free(q, 1) == 0)
+	if (xskq_prod_is_full(q))
 		return -ENOSPC;
 
 	/* A, matches D */
@@ -228,7 +230,7 @@ static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-	if (xskq_nb_free(q, 1) == 0)
+	if (xskq_prod_is_full(q))
 		return -ENOSPC;
 
 	/* A, matches D */
@@ -318,7 +320,7 @@ static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
 	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, 1);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q);
 
 		/* Order consumer and data */
 		smp_rmb(); /* C, matches B */
@@ -338,7 +340,7 @@ static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 	struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
 	u32 idx;
 
-	if (xskq_nb_free(q, 1) == 0)
+	if (xskq_prod_is_full(q))
 		return -ENOSPC;
 
 	/* A, matches D */
-- 
cgit v1.2.3-59-g8ed1b


From c5ed924b54c892ee637d2e6889ef83341835a560 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:26 +0100
Subject: xsk: Simplify the consumer ring access functions

Simplify and refactor consumer ring functions. The consumer first
"peeks" to find descriptors or addresses that are available to
read from the ring, then reads them and finally "releases" these
descriptors once it is done. The two local variables cons_tail
and cons_head are turned into one single variable called
cached_cons. cached_tail referred to the cached value of the
global consumer pointer and will be stored in cached_cons. For
cached_head, we just use cached_prod instead as it was not used
for a consumer queue before. It also better reflects what it
really is now: a cached copy of the producer pointer.

The names of the functions are also renamed in the same manner as
the producer functions. The new functions are called xskq_cons_
followed by what it does.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-8-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk.c       |  24 ++++++-------
 net/xdp/xsk_queue.h | 102 ++++++++++++++++++++++++----------------------------
 2 files changed, 58 insertions(+), 68 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 5f2123fe630c..cd84b9d0f1e1 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -41,19 +41,19 @@ bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
 
 bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
 {
-	return xskq_has_addrs(umem->fq, cnt);
+	return xskq_cons_has_entries(umem->fq, cnt);
 }
 EXPORT_SYMBOL(xsk_umem_has_addrs);
 
 u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
 {
-	return xskq_peek_addr(umem->fq, addr, umem);
+	return xskq_cons_peek_addr(umem->fq, addr, umem);
 }
 EXPORT_SYMBOL(xsk_umem_peek_addr);
 
 void xsk_umem_discard_addr(struct xdp_umem *umem)
 {
-	xskq_discard_addr(umem->fq);
+	xskq_cons_release(umem->fq);
 }
 EXPORT_SYMBOL(xsk_umem_discard_addr);
 
@@ -148,7 +148,7 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 	u32 metalen;
 	int err;
 
-	if (!xskq_peek_addr(xs->umem->fq, &addr, xs->umem) ||
+	if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
 	    len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
 		xs->rx_dropped++;
 		return -ENOSPC;
@@ -169,7 +169,7 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 	addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
 	err = xskq_prod_reserve_desc(xs->rx, addr, len);
 	if (!err) {
-		xskq_discard_addr(xs->umem->fq);
+		xskq_cons_release(xs->umem->fq);
 		xdp_return_buff(xdp);
 		return 0;
 	}
@@ -236,7 +236,7 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 		goto out_unlock;
 	}
 
-	if (!xskq_peek_addr(xs->umem->fq, &addr, xs->umem) ||
+	if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
 	    len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
 		err = -ENOSPC;
 		goto out_drop;
@@ -251,7 +251,7 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 	if (err)
 		goto out_drop;
 
-	xskq_discard_addr(xs->umem->fq);
+	xskq_cons_release(xs->umem->fq);
 	xskq_prod_submit(xs->rx);
 
 	spin_unlock_bh(&xs->rx_lock);
@@ -316,13 +316,13 @@ bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
-		if (!xskq_peek_desc(xs->tx, desc, umem))
+		if (!xskq_cons_peek_desc(xs->tx, desc, umem))
 			continue;
 
 		if (xskq_prod_reserve_addr(umem->cq, desc->addr))
 			goto out;
 
-		xskq_discard_desc(xs->tx);
+		xskq_cons_release(xs->tx);
 		rcu_read_unlock();
 		return true;
 	}
@@ -368,7 +368,7 @@ static int xsk_generic_xmit(struct sock *sk)
 	if (xs->queue_id >= xs->dev->real_num_tx_queues)
 		goto out;
 
-	while (xskq_peek_desc(xs->tx, &desc, xs->umem)) {
+	while (xskq_cons_peek_desc(xs->tx, &desc, xs->umem)) {
 		char *buffer;
 		u64 addr;
 		u32 len;
@@ -401,7 +401,7 @@ static int xsk_generic_xmit(struct sock *sk)
 		skb->destructor = xsk_destruct_skb;
 
 		err = dev_direct_xmit(skb, xs->queue_id);
-		xskq_discard_desc(xs->tx);
+		xskq_cons_release(xs->tx);
 		/* Ignore NET_XMIT_CN as packet might have been sent */
 		if (err == NET_XMIT_DROP || err == NETDEV_TX_BUSY) {
 			/* SKB completed but not sent */
@@ -472,7 +472,7 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
 
 	if (xs->rx && !xskq_prod_is_empty(xs->rx))
 		mask |= EPOLLIN | EPOLLRDNORM;
-	if (xs->tx && !xskq_full_desc(xs->tx))
+	if (xs->tx && !xskq_cons_is_full(xs->tx))
 		mask |= EPOLLOUT | EPOLLWRNORM;
 
 	return mask;
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 8bfa2ee6864c..1436116767ea 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -34,8 +34,7 @@ struct xsk_queue {
 	u32 ring_mask;
 	u32 nentries;
 	u32 cached_prod;
-	u32 cons_head;
-	u32 cons_tail;
+	u32 cached_cons;
 	struct xdp_ring *ring;
 	u64 invalid_descs;
 };
@@ -89,43 +88,48 @@ 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)
+static inline void __xskq_cons_release(struct xsk_queue *q)
 {
-	u32 entries = q->cached_prod - q->cons_tail;
+	smp_mb(); /* D, matches A */
+	WRITE_ONCE(q->ring->consumer, q->cached_cons);
+}
 
-	if (entries == 0) {
-		/* Refresh the local pointer */
-		q->cached_prod = READ_ONCE(q->ring->producer);
-		entries = q->cached_prod - q->cons_tail;
-	}
+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 */
+}
 
-	return entries;
+static inline void xskq_cons_get_entries(struct xsk_queue *q)
+{
+	__xskq_cons_release(q);
+	__xskq_cons_peek(q);
 }
 
 static inline bool xskq_prod_is_full(struct xsk_queue *q)
 {
-	u32 free_entries = q->nentries - (q->cached_prod - q->cons_tail);
+	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);
 
 	if (free_entries)
 		return false;
 
 	/* Refresh the local tail pointer */
-	q->cons_tail = READ_ONCE(q->ring->consumer);
-	free_entries = q->nentries - (q->cached_prod - q->cons_tail);
+	q->cached_cons = READ_ONCE(q->ring->consumer);
+	free_entries = q->nentries - (q->cached_prod - q->cached_cons);
 
 	return !free_entries;
 }
 
-static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
+static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
 {
-	u32 entries = q->cached_prod - q->cons_tail;
+	u32 entries = q->cached_prod - q->cached_cons;
 
 	if (entries >= cnt)
 		return true;
 
-	/* Refresh the local pointer. */
-	q->cached_prod = READ_ONCE(q->ring->producer);
-	entries = q->cached_prod - q->cons_tail;
+	__xskq_cons_peek(q);
+	entries = q->cached_prod - q->cached_cons;
 
 	return entries >= cnt;
 }
@@ -172,9 +176,10 @@ static inline bool xskq_is_valid_addr_unaligned(struct xsk_queue *q, u64 addr,
 static inline u64 *xskq_validate_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;
+
+	while (q->cached_cons != q->cached_prod) {
+		u32 idx = q->cached_cons & q->ring_mask;
 
 		*addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
 
@@ -190,30 +195,27 @@ static inline u64 *xskq_validate_addr(struct xsk_queue *q, u64 *addr,
 			return addr;
 
 out:
-		q->cons_tail++;
+		q->cached_cons++;
 	}
 
 	return NULL;
 }
 
-static inline u64 *xskq_peek_addr(struct xsk_queue *q, u64 *addr,
-				  struct xdp_umem *umem)
+static inline u64 *xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
+				       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);
-
-		/* Order consumer and data */
-		smp_rmb();
-	}
-
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
 	return xskq_validate_addr(q, addr, umem);
 }
 
-static inline void xskq_discard_addr(struct xsk_queue *q)
+static inline void xskq_cons_release(struct xsk_queue *q)
 {
-	q->cons_tail++;
+	/* To improve performance, only update local state here.
+	 * Do the actual release operation when we get new entries
+	 * from the ring in xskq_cons_get_entries() instead.
+	 */
+	q->cached_cons++;
 }
 
 static inline int xskq_prod_reserve(struct xsk_queue *q)
@@ -299,41 +301,29 @@ static inline struct xdp_desc *xskq_validate_desc(struct xsk_queue *q,
 						  struct xdp_desc *desc,
 						  struct xdp_umem *umem)
 {
-	while (q->cons_tail != q->cons_head) {
+	while (q->cached_cons != q->cached_prod) {
 		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
-		unsigned int idx = q->cons_tail & q->ring_mask;
+		u32 idx = q->cached_cons & q->ring_mask;
 
 		*desc = READ_ONCE(ring->desc[idx]);
 		if (xskq_is_valid_desc(q, desc, umem))
 			return desc;
 
-		q->cons_tail++;
+		q->cached_cons++;
 	}
 
 	return NULL;
 }
 
-static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
-					      struct xdp_desc *desc,
-					      struct xdp_umem *umem)
+static inline struct xdp_desc *xskq_cons_peek_desc(struct xsk_queue *q,
+						   struct xdp_desc *desc,
+						   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);
-
-		/* Order consumer and data */
-		smp_rmb(); /* C, matches B */
-	}
-
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
 	return xskq_validate_desc(q, desc, umem);
 }
 
-static inline void xskq_discard_desc(struct xsk_queue *q)
-{
-	q->cons_tail++;
-}
-
 static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 					 u64 addr, u32 len)
 {
@@ -351,7 +341,7 @@ static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 	return 0;
 }
 
-static inline bool xskq_full_desc(struct xsk_queue *q)
+static inline bool xskq_cons_is_full(struct xsk_queue *q)
 {
 	/* No barriers needed since data is not accessed */
 	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
-- 
cgit v1.2.3-59-g8ed1b


From 03896ef1f0cb23d2742ddf486c531c700a2da7d6 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:27 +0100
Subject: xsk: Change names of validation functions

Change the names of the validation functions to better reflect what
they are doing. The uppermost ones are reading entries from the rings
and only the bottom ones validate entries. So xskq_cons_read_ is a
better prefix name.

Also change the xskq_cons_read_ functions to return a bool
as the the descriptor or address is already returned by reference
in the parameters. Everyone is using the return value as a bool
anyway.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-9-git-send-email-magnus.karlsson@intel.com
---
 include/net/xdp_sock.h |  4 ++--
 net/xdp/xsk.c          |  4 ++--
 net/xdp/xsk_queue.h    | 59 ++++++++++++++++++++++++++------------------------
 3 files changed, 35 insertions(+), 32 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 48594740d67c..63f005830866 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -118,7 +118,7 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
 bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs);
 /* Used from netdev driver */
 bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt);
-u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr);
+bool xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr);
 void xsk_umem_discard_addr(struct xdp_umem *umem);
 void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
 bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc);
@@ -197,7 +197,7 @@ static inline bool xsk_umem_has_addrs_rq(struct xdp_umem *umem, u32 cnt)
 	return xsk_umem_has_addrs(umem, cnt - rq->length);
 }
 
-static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
+static inline bool xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
 {
 	struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
 
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index cd84b9d0f1e1..4e932a930b3a 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -45,7 +45,7 @@ bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
 }
 EXPORT_SYMBOL(xsk_umem_has_addrs);
 
-u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
+bool xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
 {
 	return xskq_cons_peek_addr(umem->fq, addr, umem);
 }
@@ -126,7 +126,7 @@ static void __xsk_rcv_memcpy(struct xdp_umem *umem, u64 addr, void *from_buf,
 	void *to_buf = xdp_umem_get_data(umem, addr);
 
 	addr = xsk_umem_add_offset_to_addr(addr);
-	if (xskq_crosses_non_contig_pg(umem, addr, len + metalen)) {
+	if (xskq_cons_crosses_non_contig_pg(umem, addr, len + metalen)) {
 		void *next_pg_addr = umem->pages[(addr >> PAGE_SHIFT) + 1].addr;
 		u64 page_start = addr & ~(PAGE_SIZE - 1);
 		u64 first_len = PAGE_SIZE - (addr - page_start);
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 1436116767ea..6d04a96dd092 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -136,8 +136,9 @@ static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
 
 /* UMEM queue */
 
-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 =
@@ -147,7 +148,7 @@ 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_addr(struct xsk_queue *q, u64 addr)
 {
 	if (addr >= q->size) {
 		q->invalid_descs++;
@@ -157,7 +158,8 @@ 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,
+static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
+						u64 addr,
 						u64 length,
 						struct xdp_umem *umem)
 {
@@ -165,7 +167,7 @@ static inline bool xskq_is_valid_addr_unaligned(struct xsk_queue *q, u64 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)) {
+	    xskq_cons_crosses_non_contig_pg(umem, addr, length)) {
 		q->invalid_descs++;
 		return false;
 	}
@@ -173,8 +175,8 @@ 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)
 {
 	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
@@ -184,29 +186,29 @@ static inline u64 *xskq_validate_addr(struct xsk_queue *q, u64 *addr,
 		*addr = READ_ONCE(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->cached_cons++;
 	}
 
-	return NULL;
+	return false;
 }
 
-static inline u64 *xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
+static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
 				       struct xdp_umem *umem)
 {
 	if (q->cached_prod == q->cached_cons)
 		xskq_cons_get_entries(q);
-	return xskq_validate_addr(q, addr, umem);
+	return xskq_cons_read_addr(q, addr, umem);
 }
 
 static inline void xskq_cons_release(struct xsk_queue *q)
@@ -270,11 +272,12 @@ static inline void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
 
 /* Rx/Tx queue */
 
-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_valid_desc(struct xsk_queue *q,
+					   struct xdp_desc *d,
+					   struct xdp_umem *umem)
 {
 	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
-		if (!xskq_is_valid_addr_unaligned(q, d->addr, d->len, umem))
+		if (!xskq_cons_is_valid_unaligned(q, d->addr, d->len, umem))
 			return false;
 
 		if (d->len > umem->chunk_size_nohr || d->options) {
@@ -285,7 +288,7 @@ static inline bool xskq_is_valid_desc(struct xsk_queue *q, struct xdp_desc *d,
 		return true;
 	}
 
-	if (!xskq_is_valid_addr(q, d->addr))
+	if (!xskq_cons_is_valid_addr(q, d->addr))
 		return false;
 
 	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
@@ -297,31 +300,31 @@ static inline bool xskq_is_valid_desc(struct xsk_queue *q, struct xdp_desc *d,
 	return true;
 }
 
-static inline struct xdp_desc *xskq_validate_desc(struct xsk_queue *q,
-						  struct xdp_desc *desc,
-						  struct xdp_umem *umem)
+static inline bool xskq_cons_read_desc(struct xsk_queue *q,
+				       struct xdp_desc *desc,
+				       struct xdp_umem *umem)
 {
 	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;
 
 		*desc = READ_ONCE(ring->desc[idx]);
-		if (xskq_is_valid_desc(q, desc, umem))
-			return desc;
+		if (xskq_cons_is_valid_desc(q, desc, umem))
+			return true;
 
 		q->cached_cons++;
 	}
 
-	return NULL;
+	return false;
 }
 
-static inline struct xdp_desc *xskq_cons_peek_desc(struct xsk_queue *q,
-						   struct xdp_desc *desc,
-						   struct xdp_umem *umem)
+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_validate_desc(q, desc, umem);
+	return xskq_cons_read_desc(q, desc, umem);
 }
 
 static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
-- 
cgit v1.2.3-59-g8ed1b


From f8509aa078de0842ec1817e8026e58620cd05d3b Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:28 +0100
Subject: xsk: ixgbe: i40e: ice: mlx5: Xsk_umem_discard_addr to
 xsk_umem_release_addr

Change the name of xsk_umem_discard_addr to xsk_umem_release_addr to
better reflect the new naming of the AF_XDP queue manipulation
functions. As this functions is used by drivers implementing support
for AF_XDP zero-copy, it requires a name change to these drivers. The
function xsk_umem_release_addr_rq has also changed name in the same
fashion.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-10-git-send-email-magnus.karlsson@intel.com
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c          |  4 ++--
 drivers/net/ethernet/intel/ice/ice_xsk.c            |  4 ++--
 drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c        |  4 ++--
 drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c |  2 +-
 include/net/xdp_sock.h                              | 10 +++++-----
 net/xdp/xsk.c                                       |  4 ++--
 6 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index d07e1a890428..20d6f11a3468 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -269,7 +269,7 @@ static bool i40e_alloc_buffer_zc(struct i40e_ring *rx_ring,
 
 	bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
 
-	xsk_umem_discard_addr(umem);
+	xsk_umem_release_addr(umem);
 	return true;
 }
 
@@ -306,7 +306,7 @@ static bool i40e_alloc_buffer_slow_zc(struct i40e_ring *rx_ring,
 
 	bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
 
-	xsk_umem_discard_addr_rq(umem);
+	xsk_umem_release_addr_rq(umem);
 	return true;
 }
 
diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index cf9b8b22d24f..0af1f0b951c0 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -555,7 +555,7 @@ ice_alloc_buf_fast_zc(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
 
 	rx_buf->handle = handle + umem->headroom;
 
-	xsk_umem_discard_addr(umem);
+	xsk_umem_release_addr(umem);
 	return true;
 }
 
@@ -591,7 +591,7 @@ ice_alloc_buf_slow_zc(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
 
 	rx_buf->handle = handle + umem->headroom;
 
-	xsk_umem_discard_addr_rq(umem);
+	xsk_umem_release_addr_rq(umem);
 	return true;
 }
 
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
index d6feaacfbf89..1501d0a22078 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -277,7 +277,7 @@ static bool ixgbe_alloc_buffer_zc(struct ixgbe_ring *rx_ring,
 
 	bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
 
-	xsk_umem_discard_addr(umem);
+	xsk_umem_release_addr(umem);
 	return true;
 }
 
@@ -304,7 +304,7 @@ static bool ixgbe_alloc_buffer_slow_zc(struct ixgbe_ring *rx_ring,
 
 	bi->handle = xsk_umem_adjust_offset(umem, handle, umem->headroom);
 
-	xsk_umem_discard_addr_rq(umem);
+	xsk_umem_release_addr_rq(umem);
 	return true;
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
index 475b6bd5d29b..62fc8a128a8d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
@@ -35,7 +35,7 @@ int mlx5e_xsk_page_alloc_umem(struct mlx5e_rq *rq,
 	 */
 	dma_info->addr = xdp_umem_get_dma(umem, handle);
 
-	xsk_umem_discard_addr_rq(umem);
+	xsk_umem_release_addr_rq(umem);
 
 	dma_sync_single_for_device(rq->pdev, dma_info->addr, PAGE_SIZE,
 				   DMA_BIDIRECTIONAL);
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 63f005830866..e86ec48ef627 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -119,7 +119,7 @@ bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs);
 /* Used from netdev driver */
 bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt);
 bool xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr);
-void xsk_umem_discard_addr(struct xdp_umem *umem);
+void xsk_umem_release_addr(struct xdp_umem *umem);
 void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
 bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc);
 void xsk_umem_consume_tx_done(struct xdp_umem *umem);
@@ -208,12 +208,12 @@ static inline bool xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
 	return addr;
 }
 
-static inline void xsk_umem_discard_addr_rq(struct xdp_umem *umem)
+static inline void xsk_umem_release_addr_rq(struct xdp_umem *umem)
 {
 	struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
 
 	if (!rq->length)
-		xsk_umem_discard_addr(umem);
+		xsk_umem_release_addr(umem);
 	else
 		rq->length--;
 }
@@ -258,7 +258,7 @@ static inline u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
 	return NULL;
 }
 
-static inline void xsk_umem_discard_addr(struct xdp_umem *umem)
+static inline void xsk_umem_release_addr(struct xdp_umem *umem)
 {
 }
 
@@ -332,7 +332,7 @@ static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
 	return NULL;
 }
 
-static inline void xsk_umem_discard_addr_rq(struct xdp_umem *umem)
+static inline void xsk_umem_release_addr_rq(struct xdp_umem *umem)
 {
 }
 
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 4e932a930b3a..55092feeaf36 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -51,11 +51,11 @@ bool xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
 }
 EXPORT_SYMBOL(xsk_umem_peek_addr);
 
-void xsk_umem_discard_addr(struct xdp_umem *umem)
+void xsk_umem_release_addr(struct xdp_umem *umem)
 {
 	xskq_cons_release(umem->fq);
 }
-EXPORT_SYMBOL(xsk_umem_discard_addr);
+EXPORT_SYMBOL(xsk_umem_release_addr);
 
 void xsk_set_rx_need_wakeup(struct xdp_umem *umem)
 {
-- 
cgit v1.2.3-59-g8ed1b


From c34787fcc90f0732ff00754057f11780007002e4 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:29 +0100
Subject: xsk: Remove unnecessary READ_ONCE of data

There are two unnecessary READ_ONCE of descriptor data. These are not
needed since the data is written by the producer before it signals
that the data is available by incrementing the producer pointer. As the
access to this producer pointer is serialized and the consumer always
reads the descriptor after it has read and synchronized with the
producer counter, the write of the descriptor will have fully
completed and it does not matter if the consumer has any read tearing.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-11-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 6d04a96dd092..4c049cacc693 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -183,7 +183,7 @@ static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
 	while (q->cached_cons != q->cached_prod) {
 		u32 idx = q->cached_cons & q->ring_mask;
 
-		*addr = READ_ONCE(ring->desc[idx]) & q->chunk_mask;
+		*addr = ring->desc[idx] & q->chunk_mask;
 
 		if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
 			if (xskq_cons_is_valid_unaligned(q, *addr,
@@ -308,7 +308,7 @@ static inline bool xskq_cons_read_desc(struct xsk_queue *q,
 		struct xdp_rxtx_ring *ring = (struct xdp_rxtx_ring *)q->ring;
 		u32 idx = q->cached_cons & q->ring_mask;
 
-		*desc = READ_ONCE(ring->desc[idx]);
+		*desc = ring->desc[idx];
 		if (xskq_cons_is_valid_desc(q, desc, umem))
 			return true;
 
-- 
cgit v1.2.3-59-g8ed1b


From 15d8c9162ced1789d25261859a7b37db8426e409 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:30 +0100
Subject: xsk: Add function naming comments and reorder functions

Add comments on how the ring access functions are named and how they
are supposed to be used for producers and consumers. The functions are
also reordered so that the consumer functions are in the beginning and
the producer functions in the end, for easier reference. Put this in a
separate patch as the diff might look a little odd, but no
functionality has changed in this patch.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-12-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk.c       |  10 ++
 net/xdp/xsk_queue.h | 293 ++++++++++++++++++++++++++++------------------------
 2 files changed, 167 insertions(+), 136 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 55092feeaf36..5560d60c1ff5 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -319,6 +319,11 @@ bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc)
 		if (!xskq_cons_peek_desc(xs->tx, desc, umem))
 			continue;
 
+		/* This is the backpreassure mechanism for the Tx path.
+		 * Reserve space in the completion queue and only proceed
+		 * if there is space in it. This avoids having to implement
+		 * any buffering in the Tx path.
+		 */
 		if (xskq_prod_reserve_addr(umem->cq, desc->addr))
 			goto out;
 
@@ -389,6 +394,11 @@ static int xsk_generic_xmit(struct sock *sk)
 		addr = desc.addr;
 		buffer = xdp_umem_get_data(xs->umem, addr);
 		err = skb_store_bits(skb, 0, buffer, len);
+		/* This is the backpreassure mechanism for the Tx path.
+		 * Reserve space in the completion queue and only proceed
+		 * if there is space in it. This avoids having to implement
+		 * any buffering in the Tx path.
+		 */
 		if (unlikely(err) || xskq_prod_reserve(xs->umem->cq)) {
 			kfree_skb(skb);
 			goto out;
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 4c049cacc693..bec2af11853a 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -81,60 +81,27 @@ 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 void __xskq_cons_release(struct xsk_queue *q)
-{
-	smp_mb(); /* D, matches A */
-	WRITE_ONCE(q->ring->consumer, q->cached_cons);
-}
-
-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 */
-}
-
-static inline void xskq_cons_get_entries(struct xsk_queue *q)
-{
-	__xskq_cons_release(q);
-	__xskq_cons_peek(q);
-}
-
-static inline bool xskq_prod_is_full(struct xsk_queue *q)
-{
-	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);
-
-	if (free_entries)
-		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 !free_entries;
-}
-
-static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
-{
-	u32 entries = q->cached_prod - q->cached_cons;
-
-	if (entries >= cnt)
-		return true;
-
-	__xskq_cons_peek(q);
-	entries = q->cached_prod - q->cached_cons;
-
-	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_cons_crosses_non_contig_pg(struct xdp_umem *umem,
 						   u64 addr,
@@ -148,16 +115,6 @@ static inline bool xskq_cons_crosses_non_contig_pg(struct xdp_umem *umem,
 	return cross_pg && !next_pg_contig;
 }
 
-static inline bool xskq_cons_is_valid_addr(struct xsk_queue *q, u64 addr)
-{
-	if (addr >= q->size) {
-		q->invalid_descs++;
-		return false;
-	}
-
-	return true;
-}
-
 static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
 						u64 addr,
 						u64 length,
@@ -175,6 +132,16 @@ static inline bool xskq_cons_is_valid_unaligned(struct xsk_queue *q,
 	return true;
 }
 
+static inline bool xskq_cons_is_valid_addr(struct xsk_queue *q, u64 addr)
+{
+	if (addr >= q->size) {
+		q->invalid_descs++;
+		return false;
+	}
+
+	return true;
+}
+
 static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
 				       struct xdp_umem *umem)
 {
@@ -203,75 +170,6 @@ out:
 	return false;
 }
 
-static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
-				       struct xdp_umem *umem)
-{
-	if (q->cached_prod == q->cached_cons)
-		xskq_cons_get_entries(q);
-	return xskq_cons_read_addr(q, addr, umem);
-}
-
-static inline void xskq_cons_release(struct xsk_queue *q)
-{
-	/* To improve performance, only update local state here.
-	 * Do the actual release operation when we get new entries
-	 * from the ring in xskq_cons_get_entries() instead.
-	 */
-	q->cached_cons++;
-}
-
-static inline int xskq_prod_reserve(struct xsk_queue *q)
-{
-	if (xskq_prod_is_full(q))
-		return -ENOSPC;
-
-	/* A, matches D */
-	q->cached_prod++;
-	return 0;
-}
-
-static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
-{
-	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
-
-	if (xskq_prod_is_full(q))
-		return -ENOSPC;
-
-	/* A, matches D */
-	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
-	return 0;
-}
-
-static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
-{
-	/* Order producer and data */
-	smp_wmb(); /* B, matches C */
-
-	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 void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
-{
-	__xskq_prod_submit(q, q->ring->producer + nb_entries);
-}
-
-/* Rx/Tx queue */
-
 static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
 					   struct xdp_desc *d,
 					   struct xdp_umem *umem)
@@ -318,6 +216,48 @@ static inline bool xskq_cons_read_desc(struct xsk_queue *q,
 	return false;
 }
 
+/* Functions for consumers */
+
+static inline void __xskq_cons_release(struct xsk_queue *q)
+{
+	smp_mb(); /* D, matches A */
+	WRITE_ONCE(q->ring->consumer, q->cached_cons);
+}
+
+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 */
+}
+
+static inline void xskq_cons_get_entries(struct xsk_queue *q)
+{
+	__xskq_cons_release(q);
+	__xskq_cons_peek(q);
+}
+
+static inline bool xskq_cons_has_entries(struct xsk_queue *q, u32 cnt)
+{
+	u32 entries = q->cached_prod - q->cached_cons;
+
+	if (entries >= cnt)
+		return true;
+
+	__xskq_cons_peek(q);
+	entries = q->cached_prod - q->cached_cons;
+
+	return entries >= cnt;
+}
+
+static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
+				       struct xdp_umem *umem)
+{
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
+	return xskq_cons_read_addr(q, addr, umem);
+}
+
 static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
 				       struct xdp_desc *desc,
 				       struct xdp_umem *umem)
@@ -327,6 +267,60 @@ static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
 	return xskq_cons_read_desc(q, desc, umem);
 }
 
+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_cons_is_full(struct xsk_queue *q)
+{
+	/* No barriers needed since data is not accessed */
+	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
+		q->nentries;
+}
+
+/* Functions for producers */
+
+static inline bool xskq_prod_is_full(struct xsk_queue *q)
+{
+	u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);
+
+	if (free_entries)
+		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 !free_entries;
+}
+
+static inline int xskq_prod_reserve(struct xsk_queue *q)
+{
+	if (xskq_prod_is_full(q))
+		return -ENOSPC;
+
+	/* A, matches D */
+	q->cached_prod++;
+	return 0;
+}
+
+static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
+{
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+
+	if (xskq_prod_is_full(q))
+		return -ENOSPC;
+
+	/* A, matches D */
+	ring->desc[q->cached_prod++ & q->ring_mask] = addr;
+	return 0;
+}
+
 static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 					 u64 addr, u32 len)
 {
@@ -344,11 +338,31 @@ static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
 	return 0;
 }
 
-static inline bool xskq_cons_is_full(struct xsk_queue *q)
+static inline void __xskq_prod_submit(struct xsk_queue *q, u32 idx)
 {
-	/* No barriers needed since data is not accessed */
-	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer) ==
-		q->nentries;
+	smp_wmb(); /* B, matches C */
+
+	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 void xskq_prod_submit_n(struct xsk_queue *q, u32 nb_entries)
+{
+	__xskq_prod_submit(q, q->ring->producer + nb_entries);
 }
 
 static inline bool xskq_prod_is_empty(struct xsk_queue *q)
@@ -357,6 +371,13 @@ static inline bool xskq_prod_is_empty(struct xsk_queue *q)
 	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);
 struct xsk_queue *xskq_create(u32 nentries, bool umem_queue);
 void xskq_destroy(struct xsk_queue *q_ops);
-- 
cgit v1.2.3-59-g8ed1b


From 1d9cb1f381860b529edec57cf7a08133f40366eb Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Thu, 19 Dec 2019 13:39:31 +0100
Subject: xsk: Use struct_size() helper

Improve readability and maintainability by using the struct_size()
helper when allocating the AF_XDP rings.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-13-git-send-email-magnus.karlsson@intel.com
---
 net/xdp/xsk_queue.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
index b66504592d9b..c90e9c1e3c63 100644
--- a/net/xdp/xsk_queue.c
+++ b/net/xdp/xsk_queue.c
@@ -18,14 +18,14 @@ void xskq_set_umem(struct xsk_queue *q, u64 size, u64 chunk_mask)
 	q->chunk_mask = chunk_mask;
 }
 
-static u32 xskq_umem_get_ring_size(struct xsk_queue *q)
+static size_t xskq_get_ring_size(struct xsk_queue *q, bool umem_queue)
 {
-	return sizeof(struct xdp_umem_ring) + q->nentries * sizeof(u64);
-}
+	struct xdp_umem_ring *umem_ring;
+	struct xdp_rxtx_ring *rxtx_ring;
 
-static u32 xskq_rxtx_get_ring_size(struct xsk_queue *q)
-{
-	return sizeof(struct xdp_ring) + q->nentries * sizeof(struct xdp_desc);
+	if (umem_queue)
+		return struct_size(umem_ring, desc, q->nentries);
+	return struct_size(rxtx_ring, desc, q->nentries);
 }
 
 struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
@@ -43,8 +43,7 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
 
 	gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN |
 		    __GFP_COMP  | __GFP_NORETRY;
-	size = umem_queue ? xskq_umem_get_ring_size(q) :
-	       xskq_rxtx_get_ring_size(q);
+	size = xskq_get_ring_size(q, umem_queue);
 
 	q->ring = (struct xdp_ring *)__get_free_pages(gfp_flags,
 						      get_order(size));
-- 
cgit v1.2.3-59-g8ed1b