linux-kernel - Re: [PATCH v3 4/7] vduse: Add function to get/free the pages for reconnection

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Date:   Thu, 7 Dec 2023 16:46:09 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cindy Lu <lulu@...hat.com>
Cc:     mst@...hat.com, xieyongji@...edance.com,
        linux-kernel@...r.kernel.org, maxime.coquelin@...hat.com
Subject: Re: [PATCH v3 4/7] vduse: Add function to get/free the pages for reconnection

On Tue, Dec 5, 2023 at 4:35 PM Cindy Lu <lulu@...hat.com> wrote:
>
> Add the function vduse_alloc_reconnnect_info_mem
> and vduse_alloc_reconnnect_info_mem
> These functions allow vduse to allocate and free memory for reconnection
> information. The amount of memory allocated is (vq_num + 1) pages.
>
> Page 0 is reserved for saving the dev reconnection information, which
> will be maintained by the Userspace App. Pages 1 to vq_num + 1 will be
> used to save the reconnection information for vqs.
>
> Signed-off-by: Cindy Lu <lulu@...hat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 64 ++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index dd074a7b4bc7..52ccde636406 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -41,6 +41,7 @@
>  #define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
>  #define VDUSE_MSG_DEFAULT_TIMEOUT 30
>
> +

Unnecessary changes.

>  struct vduse_virtqueue {
>         u16 index;
>         u16 num_max;
> @@ -57,6 +58,7 @@ struct vduse_virtqueue {
>         struct vdpa_callback cb;
>         struct work_struct inject;
>         struct work_struct kick;
> +       unsigned long vdpa_reconnect_vaddr;
>  };
>
>  struct vduse_dev;
> @@ -106,6 +108,7 @@ struct vduse_dev {
>         u32 vq_align;
>         struct vduse_umem *umem;
>         struct mutex mem_lock;
> +       unsigned long vdpa_reconnect_vaddr;
>  };
>
>  struct vduse_dev_msg {
> @@ -1030,6 +1033,57 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
>         return ret;
>  }
>
> +static int vduse_alloc_reconnnect_info_mem(struct vduse_dev *dev)
> +{
> +       unsigned long vaddr = 0;
> +       struct vduse_virtqueue *vq;
> +
> +       for (int i = 0; i < dev->vq_num + 1; i++) {
> +               if (i == 0) {
> +                       vaddr = __get_free_pages(
> +                               GFP_KERNEL | __GFP_ZERO,
> +                               get_order(VDUSE_RECONNCT_MMAP_SIZE));

order 0 should be sufficient here or anything I missed?

> +                       if (vaddr == 0)
> +                               return -ENOMEM;
> +                       dev->vdpa_reconnect_vaddr = vaddr;
> +               }
> +
> +               /*page 1~ vq_num + 1 save the reconnect info for vq*/
> +               vq = &dev->vqs[i];
> +               vaddr = __get_free_pages(GFP_KERNEL | __GFP_ZERO,
> +                                        get_order(VDUSE_RECONNCT_MMAP_SIZE));
> +               if (vaddr == 0)
> +                       return -ENOMEM;
> +
> +               vq->vdpa_reconnect_vaddr = vaddr;
> +       }
> +
> +       return 0;
> +}
> +
> +static int vduse_free_reconnnect_info_mem(struct vduse_dev *dev)
> +{
> +       struct vduse_virtqueue *vq;
> +
> +       for (int i = 0; i < dev->vq_num + 1; i++) {
> +               if (i == 0) {
> +                       if (dev->vdpa_reconnect_vaddr)
> +                               free_pages(dev->vdpa_reconnect_vaddr,
> +                                          get_order(VDUSE_RECONNCT_MMAP_SIZE));
> +                       dev->vdpa_reconnect_vaddr = 0;

Let's use NULL here.

> +               }
> +
> +               vq = &dev->vqs[i];
> +
> +               if (vq->vdpa_reconnect_vaddr)
> +                       free_pages(vq->vdpa_reconnect_vaddr,
> +                                  get_order(VDUSE_RECONNCT_MMAP_SIZE));
> +               vq->vdpa_reconnect_vaddr = 0;
> +       }
> +
> +       return 0;
> +}
> +
>  static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
>                             unsigned long arg)
>  {
> @@ -1411,6 +1465,8 @@ static int vduse_destroy_dev(char *name)
>                 mutex_unlock(&dev->lock);
>                 return -EBUSY;
>         }
> +       vduse_free_reconnnect_info_mem(dev);
> +
>         dev->connected = true;
>         mutex_unlock(&dev->lock);
>
> @@ -1563,9 +1619,17 @@ static int vduse_create_dev(struct vduse_dev_config *config,
>                 ret = PTR_ERR(dev->dev);
>                 goto err_dev;
>         }
> +
> +       ret = vduse_alloc_reconnnect_info_mem(dev);
> +       if (ret < 0)
> +               goto err_mem;
> +
>         __module_get(THIS_MODULE);
>
>         return 0;
> +
> +err_mem:
> +       vduse_free_reconnnect_info_mem(dev);
>  err_dev:
>         idr_remove(&vduse_idr, dev->minor);
>  err_idr:
> --
> 2.34.3
>

Thanks