Re: [PATCH 1/3] virtio: add virtioqueue_more_used()
From: Jason Wang <hidden>
Date: 2021-05-25 02:23:55
Also in:
linux-block, lkml
在 2021/5/20 下午10:13, Stefan Hajnoczi 写道:
Add an API to check whether there are pending used buffers. There is already a similar API called virtqueue_poll() but it only works together with virtqueue_enable_cb_prepare(). The patches that follow add blk-mq ->poll() support to virtio_blk and they need to check for used buffers without re-enabling virtqueue callbacks, so introduce an API for it. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Typo in the subject.
quoted hunk ↗ jump to hunk
--- include/linux/virtio.h | 2 ++ drivers/virtio/virtio_ring.c | 17 +++++++++++++++++ 2 files changed, 19 insertions(+)diff --git a/include/linux/virtio.h b/include/linux/virtio.h index b1894e0323fa..c6ad0f25f412 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h@@ -63,6 +63,8 @@ bool virtqueue_kick_prepare(struct virtqueue *vq); bool virtqueue_notify(struct virtqueue *vq); +bool virtqueue_more_used(const struct virtqueue *vq); + void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len); void *virtqueue_get_buf_ctx(struct virtqueue *vq, unsigned int *len,diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 71e16b53e9c1..7c3da75da462 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c@@ -2032,6 +2032,23 @@ static inline bool more_used(const struct vring_virtqueue *vq) return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq); } +/** + * virtqueue_more_used - check if there are used buffers pending + * @_vq: the struct virtqueue we're talking about. + * + * Returns true if there are used buffers, false otherwise. May be called at + * the same time as other virtqueue operations, but actually calling + * virtqueue_get_buf() requires serialization so be mindful of the race between + * calling virtqueue_more_used() and virtqueue_get_buf(). + */ +bool virtqueue_more_used(const struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + + return more_used(vq); +} +EXPORT_SYMBOL_GPL(virtqueue_more_used);
It's worth to mention that the function is not serialized (no barriers). Thanks
+
irqreturn_t vring_interrupt(int irq, void *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);_______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization