netdev - [PATCH net-next 2/6] xsk: Add API to check for available entries in FQ

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Date:   Fri, 26 Apr 2019 11:42:33 +0000
From:   Maxim Mikityanskiy <maximmi@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jonathan Lemon <bsd@...com>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Maxim Mikityanskiy <maximmi@...lanox.com>
Subject: [PATCH net-next 2/6] xsk: Add API to check for available entries in
 FQ

Add a function that checks whether the Fill Ring has the specified
amount of descriptors available. It will be useful for mlx5e that wants
to check in advance, whether it can allocate a bulk of RX descriptors,
to get the best performance.

Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
---
 include/net/xdp_sock.h | 22 ++++++++++++++++++++++
 net/xdp/xsk.c          |  8 ++++++++
 net/xdp/xsk_queue.h    | 15 +++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index d074b6d60f8a..e466b4bf68b4 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /* AF_XDP internal functions
  * Copyright(c) 2018 Intel Corporation.
+ * Copyright (c) 2019, Mellanox Technologies. All rights reserved.
  */
 
 #ifndef _LINUX_XDP_SOCK_H
@@ -77,6 +78,7 @@ int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
 void xsk_flush(struct xdp_sock *xs);
 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);
 void xsk_umem_discard_addr(struct xdp_umem *umem);
 void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
@@ -99,6 +101,16 @@ static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
 }
 
 /* Reuse-queue aware version of FILL queue helpers */
+static inline bool xsk_umem_has_addrs_rq(struct xdp_umem *umem, u32 cnt)
+{
+	struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
+
+	if (rq->length >= cnt)
+		return true;
+
+	return xsk_umem_has_addrs(umem, cnt - rq->length);
+}
+
 static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
 {
 	struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
@@ -146,6 +158,11 @@ static inline bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
 	return false;
 }
 
+static inline bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
+{
+	return false;
+}
+
 static inline u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
 {
 	return NULL;
@@ -200,6 +217,11 @@ static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
 	return 0;
 }
 
+static inline bool xsk_umem_has_addrs_rq(struct xdp_umem *umem, u32 cnt)
+{
+	return false;
+}
+
 static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
 {
 	return NULL;
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index a14e8864e4fa..ca764ed9da41 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -4,9 +4,11 @@
  * AF_XDP sockets allows a channel between XDP programs and userspace
  * applications.
  * Copyright(c) 2018 Intel Corporation.
+ * Copyright (c) 2019, Mellanox Technologies. All rights reserved.
  *
  * Author(s): Björn Töpel <bjorn.topel@...el.com>
  *	      Magnus Karlsson <magnus.karlsson@...el.com>
+ *	      Maxim Mikityanskiy <maximmi@...lanox.com>
  */
 
 #define pr_fmt(fmt) "AF_XDP: %s: " fmt, __func__
@@ -37,6 +39,12 @@ bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
 		READ_ONCE(xs->umem->fq);
 }
 
+bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
+{
+	return xskq_has_addrs(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);
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 610c0bdc0c2b..8e26aff59fd4 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /* XDP user-space ring structure
  * Copyright(c) 2018 Intel Corporation.
+ * Copyright (c) 2019, Mellanox Technologies. All rights reserved.
  */
 
 #ifndef _LINUX_XSK_QUEUE_H
@@ -75,6 +76,20 @@ static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
 	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;
+}
+
 /* UMEM queue */
 
 static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
-- 
2.19.1