[PATCH v7 08/26] virtio_ring: extract the logic of freeing vring

Xuan Zhuo
2022-03-08T12:35:54Z

Introduce vring_free() to free the vring of vq.

Prevent double free by setting vq->reset.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 25 ++++++++++++++++++++-----
include/linux/virtio.h | 8 ++++++++
2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index b5a9bf4f45b3..e0422c04c903 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2442,14 +2442,10 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
}
EXPORT_SYMBOL_GPL(vring_new_virtqueue);

-void vring_del_virtqueue(struct virtqueue *_vq)
+static void __vring_free(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);

- spin_lock(&vq->vq.vdev->vqs_list_lock);
- list_del(&_vq->list);
- spin_unlock(&vq->vq.vdev->vqs_list_lock);
-
if (vq->we_own_ring) {
if (vq->packed_ring) {
vring_free_queue(vq->vq.vdev,
@@ -2480,6 +2476,25 @@ void vring_del_virtqueue(struct virtqueue *_vq)
kfree(vq->split.desc_state);
kfree(vq->split.desc_extra);
}
+}
+
+static void vring_free(struct virtqueue *vq)
+{
+ __vring_free(vq);
+ vq->reset = VIRTIO_VQ_RESET_STEP_VRING_RELEASE;
+}
+
+void vring_del_virtqueue(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ spin_lock(&vq->vq.vdev->vqs_list_lock);
+ list_del(&_vq->list);
+ spin_unlock(&vq->vq.vdev->vqs_list_lock);
+
+ if (_vq->reset != VIRTIO_VQ_RESET_STEP_VRING_RELEASE)
+ __vring_free(_vq);
+
kfree(vq);
}
EXPORT_SYMBOL_GPL(vring_del_virtqueue);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index d59adc4be068..e3714e6db330 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -10,6 +10,13 @@
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>

+enum virtio_vq_reset_step {
+ VIRTIO_VQ_RESET_STEP_NONE,
+ VIRTIO_VQ_RESET_STEP_DEVICE,
+ VIRTIO_VQ_RESET_STEP_VRING_RELEASE,
+ VIRTIO_VQ_RESET_STEP_VRING_ATTACH,
+};
+
/**
* virtqueue - a queue to register buffers for sending or receiving.
* @list: the chain of virtqueues for this device
@@ -33,6 +40,7 @@ struct virtqueue {
unsigned int num_free;
unsigned int num_max;
void *priv;
+ enum virtio_vq_reset_step reset;
};

int virtqueue_add_outbuf(struct virtqueue *vq,
--
2.31.0