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Message-ID: <20250902080957.47265-5-simon.schippers@tu-dortmund.de>
Date: Tue, 2 Sep 2025 10:09:57 +0200
From: Simon Schippers <simon.schippers@...dortmund.de>
To: willemdebruijn.kernel@...il.com, jasowang@...hat.com, mst@...hat.com,
eperezma@...hat.com, stephen@...workplumber.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
virtualization@...ts.linux.dev, kvm@...r.kernel.org
Cc: Simon Schippers <simon.schippers@...dortmund.de>,
Tim Gebauer <tim.gebauer@...dortmund.de>
Subject: [PATCH 4/4] netdev queue flow control for vhost_net
Stopping the queue is done in tun_net_xmit.
Waking the queue is done by calling one of the helpers,
tun_wake_netdev_queue and tap_wake_netdev_queue. For that, in
get_wake_netdev_queue, the correct method is determined and saved in the
function pointer wake_netdev_queue of the vhost_net_virtqueue. Then, each
time after consuming a batch in vhost_net_buf_produce, wake_netdev_queue
is called.
Co-developed-by: Tim Gebauer <tim.gebauer@...dortmund.de>
Signed-off-by: Tim Gebauer <tim.gebauer@...dortmund.de>
Signed-off-by: Simon Schippers <simon.schippers@...dortmund.de>
---
drivers/net/tap.c | 6 ++++++
drivers/net/tun.c | 6 ++++++
drivers/vhost/net.c | 34 ++++++++++++++++++++++++++++------
include/linux/if_tap.h | 2 ++
include/linux/if_tun.h | 3 +++
5 files changed, 45 insertions(+), 6 deletions(-)
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 4d874672bcd7..0bad9e3d59af 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1198,6 +1198,12 @@ struct socket *tap_get_socket(struct file *file)
}
EXPORT_SYMBOL_GPL(tap_get_socket);
+void tap_wake_netdev_queue(struct file *file)
+{
+ wake_netdev_queue(file->private_data);
+}
+EXPORT_SYMBOL_GPL(tap_wake_netdev_queue);
+
struct ptr_ring *tap_get_ptr_ring(struct file *file)
{
struct tap_queue *q;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 735498e221d8..e85589b596ac 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3739,6 +3739,12 @@ struct socket *tun_get_socket(struct file *file)
}
EXPORT_SYMBOL_GPL(tun_get_socket);
+void tun_wake_netdev_queue(struct file *file)
+{
+ wake_netdev_queue(file->private_data);
+}
+EXPORT_SYMBOL_GPL(tun_wake_netdev_queue);
+
struct ptr_ring *tun_get_tx_ring(struct file *file)
{
struct tun_file *tfile;
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 6edac0c1ba9b..e837d3a334f1 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -130,6 +130,7 @@ struct vhost_net_virtqueue {
struct vhost_net_buf rxq;
/* Batched XDP buffs */
struct xdp_buff *xdp;
+ void (*wake_netdev_queue)(struct file *f);
};
struct vhost_net {
@@ -175,13 +176,16 @@ static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
return ret;
}
-static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
+static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq,
+ struct sock *sk)
{
+ struct file *file = sk->sk_socket->file;
struct vhost_net_buf *rxq = &nvq->rxq;
rxq->head = 0;
rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
VHOST_NET_BATCH);
+ nvq->wake_netdev_queue(file);
return rxq->tail;
}
@@ -208,14 +212,15 @@ static int vhost_net_buf_peek_len(void *ptr)
return __skb_array_len_with_tag(ptr);
}
-static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
+static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq,
+ struct sock *sk)
{
struct vhost_net_buf *rxq = &nvq->rxq;
if (!vhost_net_buf_is_empty(rxq))
goto out;
- if (!vhost_net_buf_produce(nvq))
+ if (!vhost_net_buf_produce(nvq, sk))
return 0;
out:
@@ -994,7 +999,7 @@ static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
unsigned long flags;
if (rvq->rx_ring)
- return vhost_net_buf_peek(rvq);
+ return vhost_net_buf_peek(rvq, sk);
spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
head = skb_peek(&sk->sk_receive_queue);
@@ -1499,6 +1504,19 @@ static struct socket *get_tap_socket(int fd)
return sock;
}
+static void (*get_wake_netdev_queue(struct file *file))(struct file *file)
+{
+ struct ptr_ring *ring;
+
+ ring = tun_get_tx_ring(file);
+ if (!IS_ERR(ring))
+ return tun_wake_netdev_queue;
+ ring = tap_get_ptr_ring(file);
+ if (!IS_ERR(ring))
+ return tap_wake_netdev_queue;
+ return NULL;
+}
+
static struct socket *get_socket(int fd)
{
struct socket *sock;
@@ -1570,10 +1588,14 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
if (r)
goto err_used;
if (index == VHOST_NET_VQ_RX) {
- if (sock)
+ if (sock) {
nvq->rx_ring = get_tap_ptr_ring(sock->file);
- else
+ nvq->wake_netdev_queue =
+ get_wake_netdev_queue(sock->file);
+ } else {
nvq->rx_ring = NULL;
+ nvq->wake_netdev_queue = NULL;
+ }
}
oldubufs = nvq->ubufs;
diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
index 553552fa635c..02b2809784b5 100644
--- a/include/linux/if_tap.h
+++ b/include/linux/if_tap.h
@@ -10,6 +10,7 @@ struct socket;
#if IS_ENABLED(CONFIG_TAP)
struct socket *tap_get_socket(struct file *);
+void tap_wake_netdev_queue(struct file *file);
struct ptr_ring *tap_get_ptr_ring(struct file *file);
#else
#include <linux/err.h>
@@ -18,6 +19,7 @@ static inline struct socket *tap_get_socket(struct file *f)
{
return ERR_PTR(-EINVAL);
}
+static inline void tap_wake_netdev_queue(struct file *f) {}
static inline struct ptr_ring *tap_get_ptr_ring(struct file *f)
{
return ERR_PTR(-EINVAL);
diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 80166eb62f41..04c504bb1954 100644
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -21,6 +21,7 @@ struct tun_msg_ctl {
#if defined(CONFIG_TUN) || defined(CONFIG_TUN_MODULE)
struct socket *tun_get_socket(struct file *);
+void tun_wake_netdev_queue(struct file *file);
struct ptr_ring *tun_get_tx_ring(struct file *file);
static inline bool tun_is_xdp_frame(void *ptr)
@@ -50,6 +51,8 @@ static inline struct socket *tun_get_socket(struct file *f)
return ERR_PTR(-EINVAL);
}
+static inline void tun_wake_netdev_queue(struct file *f) {}
+
static inline struct ptr_ring *tun_get_tx_ring(struct file *f)
{
return ERR_PTR(-EINVAL);
--
2.43.0
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