netdev - [PATCH net-next 3/3] xsk: convert cq from spin lock protection into atomic operations

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Message-Id: <20251124080858.89593-4-kerneljasonxing@gmail.com>
Date: Mon, 24 Nov 2025 16:08:58 +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 3/3] xsk: convert cq from spin lock protection into atomic operations

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

Now it's time to convert cq in generic path into atomic operations
to achieve a higher performance number. I managed to see it improve
around 5% over different platforms.

Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 include/net/xsk_buff_pool.h |  5 -----
 net/xdp/xsk.c               | 12 ++----------
 net/xdp/xsk_buff_pool.c     |  1 -
 3 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 92a2358c6ce3..0b1abdb99c9e 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -90,11 +90,6 @@ struct xsk_buff_pool {
 	 * destructor callback.
 	 */
 	spinlock_t cq_prod_lock;
-	/* Mutual exclusion of the completion ring in the SKB mode.
-	 * Protect: when sockets share a single cq when the same netdev
-	 * and queue id is shared.
-	 */
-	spinlock_t cq_cached_prod_lock;
 	struct xdp_buff_xsk *free_heads[];
 };
 
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 4e95b894f218..6b99a7eeb952 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -548,13 +548,7 @@ static int xsk_wakeup(struct xdp_sock *xs, u8 flags)
 
 static int xsk_cq_reserve_locked(struct xsk_buff_pool *pool)
 {
-	int ret;
-
-	spin_lock(&pool->cq_cached_prod_lock);
-	ret = xskq_prod_reserve(pool->cq, false);
-	spin_unlock(&pool->cq_cached_prod_lock);
-
-	return ret;
+	return xskq_prod_reserve(pool->cq, true);
 }
 
 static void xsk_cq_submit_addr_locked(struct xsk_buff_pool *pool,
@@ -587,9 +581,7 @@ static void xsk_cq_submit_addr_locked(struct xsk_buff_pool *pool,
 
 static void xsk_cq_cancel_locked(struct xsk_buff_pool *pool, u32 n)
 {
-	spin_lock(&pool->cq_cached_prod_lock);
-	xskq_prod_cancel_n(pool->cq, n, false);
-	spin_unlock(&pool->cq_cached_prod_lock);
+	xskq_prod_cancel_n(pool->cq, n, true);
 }
 
 static void xsk_inc_num_desc(struct sk_buff *skb)
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 51526034c42a..9539f121b290 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -91,7 +91,6 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
 	INIT_LIST_HEAD(&pool->xsk_tx_list);
 	spin_lock_init(&pool->xsk_tx_list_lock);
 	spin_lock_init(&pool->cq_prod_lock);
-	spin_lock_init(&pool->cq_cached_prod_lock);
 	refcount_set(&pool->users, 1);
 
 	pool->fq = xs->fq_tmp;
-- 
2.41.3