netdev - [PATCH net-next 1/3] xsk: add atomic cached

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Message-Id: <20251124080858.89593-2-kerneljasonxing@gmail.com>
Date: Mon, 24 Nov 2025 16:08:56 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	bjorn@...nel.org,
	magnus.karlsson@...el.com,
	maciej.fijalkowski@...el.com,
	jonathan.lemon@...il.com,
	sdf@...ichev.me,
	ast@...nel.org,
	daniel@...earbox.net,
	hawk@...nel.org,
	john.fastabend@...il.com
Cc: bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net-next 1/3] xsk: add atomic cached_prod for copy mode

From: Jason Xing <kernelxing@...cent.com>

Add a union member for completion queue only in copy mode for now. The
purpose is to replace the cq_cached_prod_lock with atomic operation
to improve performance. Note that completion queue in zerocopy mode
doesn't need to be converted because the whole process is lockless.

Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 net/xdp/xsk_queue.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 1eb8d9f8b104..44cc01555c0b 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -40,7 +40,11 @@ struct xdp_umem_ring {
 struct xsk_queue {
 	u32 ring_mask;
 	u32 nentries;
-	u32 cached_prod;
+	union {
+		u32 cached_prod;
+		/* Used for cq in copy mode only */
+		atomic_t cached_prod_atomic;
+	};
 	u32 cached_cons;
 	struct xdp_ring *ring;
 	u64 invalid_descs;
-- 
2.41.3