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Date:   Mon, 2 Jul 2018 10:21:04 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     xiangxia.m.yue@...il.com
Cc:     mst@...hat.com, makita.toshiaki@....ntt.co.jp,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        Tonghao Zhang <zhangtonghao@...ichuxing.com>
Subject: Re: [PATCH net-next v3 1/4] net: vhost: lock the vqs one by one



On 2018年06月30日 14:33, xiangxia.m.yue@...il.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue@...il.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 <zhangtonghao@...ichuxing.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 895eaa2..4ca9383 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,
> @@ -887,20 +890,6 @@ 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)
> @@ -950,7 +939,10 @@ 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);
>   		}
> @@ -982,7 +974,6 @@ 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) {
> @@ -1016,7 +1007,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
>   		break;
>   	}
>   
> -	vhost_dev_unlock_vqs(dev);
>   	mutex_unlock(&dev->mutex);
>   
>   	return ret;

Acked-by: Jason Wang <jasowang@...hat.com>
Signed-off-by: Jason Wang <jasowang@...hat.com>

Thanks

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