On 2020/11/5 上午6:26, Mike Christie wrote:
The next patches allow us to create vqs on demand after vhost_dev_init
and vhost_dev_set_owner have been called. For vhost-scsi we don't
know the number of vqs we really want until the vring/vq setup
operations have started up. For other devices we know the number of vqs
at vhost_dev_init time, so for those devs we init the vq and allocate
the needed iovecs. For vhost-scsi we will do it later when userspace has
indicated to us that it's going to use a vq.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/vhost/vhost.c | 71 +++++++++++++++++++++++++++------------------------
1 file changed, 38 insertions(+), 33 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index b35229e..a4a4450 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -383,29 +383,27 @@ static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
vq->heads = NULL;
}
-/* Helper to allocate iovec buffers for all vqs. */
-static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
+static int vhost_vq_alloc_iovecs(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
{
- struct vhost_virtqueue *vq;
- int i;
+ vq->indirect = kmalloc_array(UIO_MAXIOV, sizeof(*vq->indirect),
+ GFP_KERNEL);
+ if (!vq->indirect)
+ return -ENOMEM;
+
+ if (!dev->iov_limit)
+ return 0;
This looks like an optimization. Let's try to defer this into another patch.
+
+ vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log), GFP_KERNEL);
+ vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
+ GFP_KERNEL);
+ if (!vq->log || !vq->heads)
+ goto err_nomem;
- for (i = 0; i < dev->nvqs; ++i) {
- vq = dev->vqs[i];
- vq->indirect = kmalloc_array(UIO_MAXIOV,
- sizeof(*vq->indirect),
- GFP_KERNEL);
- vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
- GFP_KERNEL);
- vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
- GFP_KERNEL);
- if (!vq->indirect || !vq->log || !vq->heads)
- goto err_nomem;
- }
return 0;
err_nomem:
- for (; i >= 0; --i)
- vhost_vq_free_iovecs(dev->vqs[i]);
+ vhost_vq_free_iovecs(vq);
return -ENOMEM;
}
@@ -458,6 +456,21 @@ static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
return sizeof(*vq->desc) * num;
}
+static int vhost_vq_init(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+ vq->log = NULL;
+ vq->indirect = NULL;
+ vq->heads = NULL;
+ vq->dev = dev;
+ mutex_init(&vq->mutex);
+ vhost_vq_reset(dev, vq);
+
+ if (vq->handle_kick)
+ vhost_poll_init(&vq->poll, vq->handle_kick, EPOLLIN, dev);
+
+ return vhost_vq_alloc_iovecs(dev, vq);
+}
If it's possible, I would do a patch to introduce vhost_vq_init() and
then add vhost_vq_alloc_iovecs() on top.
Thanks
+
int vhost_dev_init(struct vhost_dev *dev,
struct vhost_virtqueue **vqs, int nvqs,
int iov_limit, int weight, int byte_weight,
@@ -465,7 +478,6 @@ int vhost_dev_init(struct vhost_dev *dev,
int (*msg_handler)(struct vhost_dev *dev,
struct vhost_iotlb_msg *msg))
{
- struct vhost_virtqueue *vq;
int i;
dev->vqs = vqs;
@@ -489,19 +501,16 @@ int vhost_dev_init(struct vhost_dev *dev,
for (i = 0; i < dev->nvqs; ++i) {
- vq = dev->vqs[i];
- vq->log = NULL;
- vq->indirect = NULL;
- vq->heads = NULL;
- vq->dev = dev;
- mutex_init(&vq->mutex);
- vhost_vq_reset(dev, vq);
- if (vq->handle_kick)
- vhost_poll_init(&vq->poll, vq->handle_kick,
- EPOLLIN, dev);
+ if (vhost_vq_init(dev, dev->vqs[i]))
+ goto err_vq_init;
}
return 0;
+
+err_vq_init:
+ for (--i; i >= 0; --i)
+ vhost_vq_free_iovecs(dev->vqs[i]);
+ return -ENOMEM;
}
EXPORT_SYMBOL_GPL(vhost_dev_init);
@@ -606,10 +615,6 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
goto err_cgroup;
}
- err = vhost_dev_alloc_iovecs(dev);
- if (err)
- goto err_cgroup;
-
return 0;
err_cgroup:
if (dev->worker) {
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