netdev - [PATCH bpf-next 07/21] xsk: allow core/drivers to test EOP bit

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Date: Thu, 18 May 2023 20:05:31 +0200
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: bpf@...r.kernel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org
Cc: netdev@...r.kernel.org,
	magnus.karlsson@...el.com,
	tirthendu.sarkar@...el.com,
	maciej.fijalkowski@...el.com,
	bjorn@...nel.org
Subject: [PATCH bpf-next 07/21] xsk: allow core/drivers to test EOP bit

Drivers are used to check for EOP bit whereas AF_XDP operates on
inverted logic - user space indicates that current frag is not the last
one and packet continues. For AF_XDP core needs, add xp_mb_desc() that
will simply test XDP_PKT_CONTD from xdp_desc::options, but in order to
preserve drivers default behavior, introduce an interface for ZC drivers
that will negate xp_mb_desc() result and therefore make it easier to
test EOP bit from during production of HW Tx descriptors.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 include/net/xdp_sock_drv.h  | 10 ++++++++++
 include/net/xsk_buff_pool.h |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index 9c0d860609ba..a3e18b958d93 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h
@@ -89,6 +89,11 @@ static inline struct xdp_buff *xsk_buff_alloc(struct xsk_buff_pool *pool)
 	return xp_alloc(pool);
 }
 
+static inline bool xsk_is_eop_desc(struct xdp_desc *desc)
+{
+	return !xp_mb_desc(desc);
+}
+
 /* Returns as many entries as possible up to max. 0 <= N <= max. */
 static inline u32 xsk_buff_alloc_batch(struct xsk_buff_pool *pool, struct xdp_buff **xdp, u32 max)
 {
@@ -241,6 +246,11 @@ static inline struct xdp_buff *xsk_buff_alloc(struct xsk_buff_pool *pool)
 	return NULL;
 }
 
+static inline bool xsk_is_eop_desc(struct xdp_desc *desc)
+{
+	return false;
+}
+
 static inline u32 xsk_buff_alloc_batch(struct xsk_buff_pool *pool, struct xdp_buff **xdp, u32 max)
 {
 	return 0;
diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index a8d7b8a3688a..4dcca163e076 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -184,6 +184,11 @@ static inline bool xp_desc_crosses_non_contig_pg(struct xsk_buff_pool *pool,
 	       !(pool->dma_pages[addr >> PAGE_SHIFT] & XSK_NEXT_PG_CONTIG_MASK);
 }
 
+static inline bool xp_mb_desc(struct xdp_desc *desc)
+{
+	return desc->options & XDP_PKT_CONTD;
+}
+
 static inline u64 xp_aligned_extract_addr(struct xsk_buff_pool *pool, u64 addr)
 {
 	return addr & pool->chunk_mask;
-- 
2.34.1