This patch introduces a per virtqueue waitqueue to allow driver to
sleep and wait for more used. Two new helpers are introduced to allow
driver to sleep and wake up.
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
Changes since V1:
- check virtqueue_is_broken() as well
- use more_used() instead of virtqueue_get_buf() to allow caller to
get buffers afterwards
---
drivers/virtio/virtio_ring.c | 29 +++++++++++++++++++++++++++++
include/linux/virtio.h | 3 +++
2 files changed, 32 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5cfb2fa8abee..9c83eb945493 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -13,6 +13,7 @@
#include <linux/dma-mapping.h>
#include <linux/kmsan.h>
#include <linux/spinlock.h>
+#include <linux/wait.h>
#include <xen/xen.h>
#ifdef DEBUG
@@ -60,6 +61,7 @@
"%s:"fmt, (_vq)->vq.name, ##args); \
/* Pairs with READ_ONCE() in virtqueue_is_broken(). */ \
WRITE_ONCE((_vq)->broken, true); \
+ wake_up_interruptible(&(_vq)->wq); \
} while (0)
#define START_USE(vq)
#define END_USE(vq)
@@ -203,6 +205,9 @@ struct vring_virtqueue {
/* DMA, allocation, and size information */
bool we_own_ring;
+ /* Wait for buffer to be used */
+ wait_queue_head_t wq;
+
#ifdef DEBUG
/* They're supposed to lock for us. */
unsigned int in_use;
@@ -2024,6 +2029,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
vq->weak_barriers = false;
+ init_waitqueue_head(&vq->wq);
+
err = vring_alloc_state_extra_packed(&vring_packed);
if (err)
goto err_state_extra;
@@ -2517,6 +2524,8 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index,
if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
vq->weak_barriers = false;
+ init_waitqueue_head(&vq->wq);
+
err = vring_alloc_state_extra_split(vring_split);
if (err) {
kfree(vq);
@@ -2654,6 +2663,8 @@ static void vring_free(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
+ wake_up_interruptible(&vq->wq);
+
if (vq->we_own_ring) {
if (vq->packed_ring) {
vring_free_queue(vq->vq.vdev,
@@ -2863,4 +2874,22 @@ const struct vring *virtqueue_get_vring(struct virtqueue *vq)
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);
+int virtqueue_wait_for_used(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ /* TODO: Tweak the timeout. */
+ return wait_event_interruptible_timeout(vq->wq,
+ virtqueue_is_broken(_vq) || more_used(vq), HZ);
+}
+EXPORT_SYMBOL_GPL(virtqueue_wait_for_used);
+
+void virtqueue_wake_up(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ wake_up_interruptible(&vq->wq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_wake_up);
+
MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index dcab9c7e8784..2eb62c774895 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -72,6 +72,9 @@ void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
void *virtqueue_get_buf_ctx(struct virtqueue *vq, unsigned int *len,
void **ctx);
+int virtqueue_wait_for_used(struct virtqueue *vq);
+void virtqueue_wake_up(struct virtqueue *vq);
+
void virtqueue_disable_cb(struct virtqueue *vq);
bool virtqueue_enable_cb(struct virtqueue *vq);
--
2.25.1
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