[Qemu-block] 答复: [PATCH] scsi-disk: Fix crash if request is invaild or disk is no medium

[lizhengui]

This problem can be reproduced by detaching and attaching remote cdrom repeatly.

-----邮件原件-----
发件人: John Snow [mailto:address@hidden 
发送时间: 2019年3月19日 7:34
收件人: lizhengui; address@hidden; address@hidden; address@hidden
抄送: address@hidden; Fangyi (C); address@hidden; wangjie (P)
主题: Re: [Qemu-block] [PATCH] scsi-disk: Fix crash if request is invaild or disk 
is no medium



On 3/7/19 3:57 AM, Zhengui li wrote:
> From: Zhengui Li <address@hidden>
> 
> Qemu will crash with the assertion error that "assert(r->req.aiocb !=
> NULL)" in scsi_read_complete if request is invaild or disk is no medium.
> The error is below:
> qemu-kvm: hw/scsi/scsi_disk.c:299: scsi_read_complete: Assertion
> `r->req.aiocb != NULL' failed.
> 
> This patch add a funtion scsi_read_complete_noio to fix it.
> 

How do you reproduce this? Is there a test?

--js

> Signed-off-by: Zhengui Li <address@hidden>
> ---
>  hw/scsi/scsi-disk.c | 37 ++++++++++++++++++++++++-------------
>  1 file changed, 24 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index d4e83ae..624df3c 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -296,22 +296,15 @@ static void scsi_dma_complete(void *opaque, int ret)
>      aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
>  }
>  
> -static void scsi_read_complete(void * opaque, int ret)
> +static void scsi_read_complete_noio(SCSIDiskReq *r, int ret)
>  {
> -    SCSIDiskReq *r = (SCSIDiskReq *)opaque;
> -    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
> -    int n;
> +    uint32_t n;
>  
> -    assert(r->req.aiocb != NULL);
> -    r->req.aiocb = NULL;
> -    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
> -    if (scsi_disk_req_check_error(r, ret, true)) {
> +    assert (r->req.aiocb == NULL);
> +    if (scsi_disk_req_check_error(r, ret, false)) {
>          goto done;
>      }
>  
> -    block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
> -    trace_scsi_disk_read_complete(r->req.tag, r->qiov.size);
> -
>      n = r->qiov.size / 512;
>      r->sector += n;
>      r->sector_count -= n;
> @@ -319,6 +312,24 @@ static void scsi_read_complete(void * opaque, int ret)
>  
>  done:
>      scsi_req_unref(&r->req);
> +}
> +
> +static void scsi_read_complete(void * opaque, int ret)
> +{
> +    SCSIDiskReq *r = (SCSIDiskReq *)opaque;
> +    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
> +
> +    assert(r->req.aiocb != NULL);
> +    r->req.aiocb = NULL;
> +
> +    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
> +    if (ret < 0) {
> +        block_acct_failed(blk_get_stats(s->qdev.conf.blk), &r->acct);
> +    } else {
> +        block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
> +        trace_scsi_disk_read_complete(r->req.tag, r->qiov.size);
> +    }
> +    scsi_read_complete_noio(r, ret);
>      aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
>  }
>  
> @@ -395,12 +406,12 @@ static void scsi_read_data(SCSIRequest *req)
>      scsi_req_ref(&r->req);
>      if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
>          trace_scsi_disk_read_data_invalid();
> -        scsi_read_complete(r, -EINVAL);
> +        scsi_read_complete_noio(r, -EINVAL);
>          return;
>      }
>  
>      if (!blk_is_available(req->dev->conf.blk)) {
> -        scsi_read_complete(r, -ENOMEDIUM);
> +        scsi_read_complete_noio(r, -ENOMEDIUM);
>          return;
>      }
>  
>