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Tsirkin" To: Jason Wang Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, maxime.coquelin@redhat.com, alvaro.karsz@solid-run.com, eperezma@redhat.com Subject: Re: [PATCH 3/4] virtio_ring: introduce a per virtqueue waitqueue Message-ID: <20221226183348-mutt-send-email-mst@kernel.org> References: <20221226074908.8154-1-jasowang@redhat.com> <20221226074908.8154-4-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221226074908.8154-4-jasowang@redhat.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Dec 26, 2022 at 03:49:07PM +0800, Jason Wang wrote: > 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 > --- > 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 > #include > #include > +#include > #include > > #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); There's no good timeout. Let's not even go there, if device goes bad it should set the need reset bit. > +} > +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