From: Tonghao Zhang <xiangxia.m....@gmail.com>

This patch changes the way that lock all vqs
at the same, to lock them one by one. It will
be used for next patch to avoid the deadlock.

Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
Acked-by: Jason Wang <jasow...@redhat.com>
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/vhost/vhost.c | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a502f1a..a1c06e7 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -294,8 +294,11 @@ static void vhost_vq_meta_reset(struct vhost_dev *d)
 {
        int i;
 
-       for (i = 0; i < d->nvqs; ++i)
+       for (i = 0; i < d->nvqs; ++i) {
+               mutex_lock(&d->vqs[i]->mutex);
                __vhost_vq_meta_reset(d->vqs[i]);
+               mutex_unlock(&d->vqs[i]->mutex);
+       }
 }
 
 static void vhost_vq_reset(struct vhost_dev *dev,
@@ -890,20 +893,6 @@ static inline void __user *__vhost_get_user(struct 
vhost_virtqueue *vq,
 #define vhost_get_used(vq, x, ptr) \
        vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
 
-static void vhost_dev_lock_vqs(struct vhost_dev *d)
-{
-       int i = 0;
-       for (i = 0; i < d->nvqs; ++i)
-               mutex_lock_nested(&d->vqs[i]->mutex, i);
-}
-
-static void vhost_dev_unlock_vqs(struct vhost_dev *d)
-{
-       int i = 0;
-       for (i = 0; i < d->nvqs; ++i)
-               mutex_unlock(&d->vqs[i]->mutex);
-}
-
 static int vhost_new_umem_range(struct vhost_umem *umem,
                                u64 start, u64 size, u64 end,
                                u64 userspace_addr, int perm)
@@ -953,7 +942,10 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
                if (msg->iova <= vq_msg->iova &&
                    msg->iova + msg->size - 1 > vq_msg->iova &&
                    vq_msg->type == VHOST_IOTLB_MISS) {
+                       mutex_lock(&node->vq->mutex);
                        vhost_poll_queue(&node->vq->poll);
+                       mutex_unlock(&node->vq->mutex);
+
                        list_del(&node->node);
                        kfree(node);
                }
@@ -985,7 +977,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
        int ret = 0;
 
        mutex_lock(&dev->mutex);
-       vhost_dev_lock_vqs(dev);
        switch (msg->type) {
        case VHOST_IOTLB_UPDATE:
                if (!dev->iotlb) {
@@ -1019,7 +1010,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
                break;
        }
 
-       vhost_dev_unlock_vqs(dev);
        mutex_unlock(&dev->mutex);
 
        return ret;
-- 
1.8.3.1

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