[PATCH RFC net-next v4 10/14] xsk: extend xsk_cq_reserve_locked() to reserve n slots

Jason Xing
2026-04-15T08:28:08Z

Previously it only reserves one slot. The patch extends it to n to cover
the batch mode.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
net/xdp/xsk.c | 12 ++++++++----
net/xdp/xsk_queue.h | 12 +++++++-----
2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 6cd2e58e170c..c26e26cb4dda 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -546,12 +546,17 @@ static int xsk_wakeup(struct xdp_sock *xs, u8 flags)
return dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, flags);
}

-static int xsk_cq_reserve_locked(struct xsk_buff_pool *pool)
+/* The function tries to reserve as many descs as possible. If there
+ * is no single slot to allocate, return zero. Otherwise, return how
+ * many slots are available, even though it might stop reserving at
+ * certain point.
+ */
+static int xsk_cq_reserve_locked(struct xsk_buff_pool *pool, u32 n)
{
int ret;

spin_lock(&pool->cq->cq_cached_prod_lock);
- ret = xskq_prod_reserve(pool->cq);
+ ret = xskq_prod_reserve(pool->cq, n);
spin_unlock(&pool->cq->cq_cached_prod_lock);

return ret;
@@ -947,8 +952,7 @@ static int __xsk_generic_xmit(struct sock *sk)
* if there is space in it. This avoids having to implement
* any buffering in the Tx path.
*/
- err = xsk_cq_reserve_locked(xs->pool);
- if (err) {
+ if (!xsk_cq_reserve_locked(xs->pool, 1)) {
err = -EAGAIN;
goto out;
}
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 354f6fe86893..34cc07d6115e 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -413,14 +413,16 @@ static inline void xskq_prod_cancel_n(struct xsk_queue *q, u32 cnt)
q->cached_prod -= cnt;
}

-static inline int xskq_prod_reserve(struct xsk_queue *q)
+static inline int xskq_prod_reserve(struct xsk_queue *q, u32 n)
{
- if (xskq_prod_is_full(q))
- return -ENOSPC;
+ u32 nr_free = xskq_prod_nb_free(q, n);
+
+ if (!nr_free)
+ return 0;

/* A, matches D */
- q->cached_prod++;
- return 0;
+ q->cached_prod += nr_free;
+ return nr_free;
}

static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
--
2.41.3