| Message ID | 20210520141305.355961-2-stefanha@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio_blk: blk-mq io_poll support | expand |
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. > --- > 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);
On Tue, May 25, 2021 at 10:23:39AM +0800, Jason Wang wrote: > > 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. Thanks, will fix. > > +/** > > + * 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, will fix. Stefan
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); + irqreturn_t vring_interrupt(int irq, void *_vq) { struct vring_virtqueue *vq = to_vvq(_vq);
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> --- include/linux/virtio.h | 2 ++ drivers/virtio/virtio_ring.c | 17 +++++++++++++++++ 2 files changed, 19 insertions(+)