netdev - [PATCH net v2 1/2] virtio: add a new parameter in struct virtqueue

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Date:   Fri, 19 Feb 2021 17:44:35 -0800
From:   Wei Wang <weiwan@...gle.com>
To:     "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Willem de Bruijn <willemb@...gle.com>,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: [PATCH net v2 1/2] virtio: add a new parameter in struct virtqueue

The new parameter is set to suppress the warning in the interrupt
handler when no work needs to be done.
This will be used for virtio net driver in the following patch.

Signed-off-by: Wei Wang <weiwan@...gle.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 drivers/virtio/virtio_ring.c | 16 ++++++++++++++++
 include/linux/virtio.h       |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 71e16b53e9c1..3c5ac1b26dff 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -105,6 +105,9 @@ struct vring_virtqueue {
 	/* Host publishes avail event idx */
 	bool event;
 
+	/* Suppress warning in interrupt handler */
+	bool no_interrupt_check;
+
 	/* Head of free buffer list. */
 	unsigned int free_head;
 	/* Number we've added since last sync. */
@@ -1604,6 +1607,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
 	vq->broken = false;
+	vq->no_interrupt_check = false;
 	vq->last_used_idx = 0;
 	vq->num_added = 0;
 	vq->packed_ring = true;
@@ -2037,6 +2041,9 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
 	if (!more_used(vq)) {
+		if (vq->no_interrupt_check)
+			return IRQ_HANDLED;
+
 		pr_debug("virtqueue interrupt with no work for %p\n", vq);
 		return IRQ_NONE;
 	}
@@ -2082,6 +2089,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
 	vq->broken = false;
+	vq->no_interrupt_check = false;
 	vq->last_used_idx = 0;
 	vq->num_added = 0;
 	vq->use_dma_api = vring_use_dma_api(vdev);
@@ -2266,6 +2274,14 @@ bool virtqueue_is_broken(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_is_broken);
 
+void virtqueue_set_no_interrupt_check(struct virtqueue *_vq, bool val)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	vq->no_interrupt_check = val;
+}
+EXPORT_SYMBOL_GPL(virtqueue_set_no_interrupt_check);
+
 /*
  * This should prevent the device from being used, allowing drivers to
  * recover.  You may need to grab appropriate locks to flush.
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 55ea329fe72a..27b374df78cc 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -84,6 +84,8 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
 
 bool virtqueue_is_broken(struct virtqueue *vq);
 
+void virtqueue_set_no_interrupt_check(struct virtqueue *vq, bool val);
+
 const struct vring *virtqueue_get_vring(struct virtqueue *vq);
 dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
 dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
-- 
2.30.0.617.g56c4b15f3c-goog