Add {tun,tap}_ring_consume_batched() that wrap
__ptr_ring_consume_batched() and wake the corresponding netdev subqueue
when consuming the entries frees space in the ptr_ring.

These wrappers are supposed to be used by vhost-net in an upcoming
commit.

Co-developed-by: Tim Gebauer <tim.gebauer@tu-dortmund.de>
Signed-off-by: Tim Gebauer <tim.gebauer@tu-dortmund.de>
Signed-off-by: Simon Schippers <simon.schippers@tu-dortmund.de>
---
 drivers/net/tap.c      | 23 +++++++++++++++++++++++
 drivers/net/tun.c      | 23 +++++++++++++++++++++++
 include/linux/if_tap.h |  6 ++++++
 include/linux/if_tun.h |  7 +++++++
 4 files changed, 59 insertions(+)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 2442cf7ac385..7e3b4eed797c 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -774,6 +774,29 @@ static void *tap_ring_consume(struct tap_queue *q)
 	return ptr;
 }
 
+int tap_ring_consume_batched(struct file *file, void **array, int n)
+{
+	struct tap_queue *q = file->private_data;
+	struct ptr_ring *ring = &q->ring;
+	struct net_device *dev;
+	int i;
+
+	spin_lock(&ring->consumer_lock);
+
+	i = __ptr_ring_consume_batched(ring, array, n);
+	if (__ptr_ring_consume_created_space(ring, i)) {
+		rcu_read_lock();
+		dev = rcu_dereference(q->tap)->dev;
+		netif_wake_subqueue(dev, q->queue_index);
+		rcu_read_unlock();
+	}
+
+	spin_unlock(&ring->consumer_lock);
+
+	return i;
+}
+EXPORT_SYMBOL_GPL(tap_ring_consume_batched);
+
 static ssize_t tap_do_read(struct tap_queue *q,
 			   struct iov_iter *to,
 			   int noblock, struct sk_buff *skb)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7148f9a844a4..db3b72025cfb 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3736,6 +3736,29 @@ struct socket *tun_get_socket(struct file *file)
 }
 EXPORT_SYMBOL_GPL(tun_get_socket);
 
+int tun_ring_consume_batched(struct file *file, void **array, int n)
+{
+	struct tun_file *tfile = file->private_data;
+	struct ptr_ring *ring = &tfile->tx_ring;
+	struct net_device *dev;
+	int i;
+
+	spin_lock(&ring->consumer_lock);
+
+	i = __ptr_ring_consume_batched(ring, array, n);
+	if (__ptr_ring_consume_created_space(ring, i)) {
+		rcu_read_lock();
+		dev = rcu_dereference(tfile->tun)->dev;
+		netif_wake_subqueue(dev, tfile->queue_index);
+		rcu_read_unlock();
+	}
+
+	spin_unlock(&ring->consumer_lock);
+
+	return i;
+}
+EXPORT_SYMBOL_GPL(tun_ring_consume_batched);
+
 struct ptr_ring *tun_get_tx_ring(struct file *file)
 {
 	struct tun_file *tfile;
diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
index 553552fa635c..cf8b90320b8d 100644
--- a/include/linux/if_tap.h
+++ b/include/linux/if_tap.h
@@ -11,6 +11,7 @@ struct socket;
 #if IS_ENABLED(CONFIG_TAP)
 struct socket *tap_get_socket(struct file *);
 struct ptr_ring *tap_get_ptr_ring(struct file *file);
+int tap_ring_consume_batched(struct file *file, void **array, int n);
 #else
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -22,6 +23,11 @@ static inline struct ptr_ring *tap_get_ptr_ring(struct file *f)
 {
 	return ERR_PTR(-EINVAL);
 }
+static inline int tap_ring_consume_batched(struct file *f,
+					   void **array, int n)
+{
+	return 0;
+}
 #endif /* CONFIG_TAP */
 
 /*
diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 80166eb62f41..444dda75a372 100644
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -22,6 +22,7 @@ struct tun_msg_ctl {
 #if defined(CONFIG_TUN) || defined(CONFIG_TUN_MODULE)
 struct socket *tun_get_socket(struct file *);
 struct ptr_ring *tun_get_tx_ring(struct file *file);
+int tun_ring_consume_batched(struct file *file, void **array, int n);
 
 static inline bool tun_is_xdp_frame(void *ptr)
 {
@@ -55,6 +56,12 @@ static inline struct ptr_ring *tun_get_tx_ring(struct file *f)
 	return ERR_PTR(-EINVAL);
 }
 
+static inline int tun_ring_consume_batched(struct file *file,
+					   void **array, int n)
+{
+	return 0;
+}
+
 static inline bool tun_is_xdp_frame(void *ptr)
 {
 	return false;
-- 
2.43.0