Re: [RFC v3 04/11] vhost-vdpa: protect concurrent access to vhost device iotlb

Introduce a mutex to protect vhost device iotlb from
concurrent access.

Fixes: 4c8cf318("vhost: introduce vDPA-based backend")
Signed-off-by: Xie Yongji <redacted>
---
  drivers/vhost/vdpa.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 448be7875b6d..4a241d380c40 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -49,6 +49,7 @@ struct vhost_vdpa {
  	struct eventfd_ctx *config_ctx;
  	int in_batch;
  	struct vdpa_iova_range range;
+	struct mutex mutex;

  };
  
  static DEFINE_IDA(vhost_vdpa_ida);

@@ -728,6 +729,7 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
  	if (r)
  		return r;
  
+	mutex_lock(&v->mutex);
  	switch (msg->type) {
  	case VHOST_IOTLB_UPDATE:
  		r = vhost_vdpa_process_iotlb_update(v, msg);

@@ -747,6 +749,7 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
  		r = -EINVAL;
  		break;
  	}
+	mutex_unlock(&v->mutex);
  
  	return r;
  }

@@ -1017,6 +1020,7 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
  		return minor;
  	}
  
+	mutex_init(&v->mutex);
  	atomic_set(&v->opened, 0);
  	v->minor = minor;
  	v->vdpa = vdpa;