Re: [RFC PATCH 2/4] hw/scsi/scsi-disk: Use automatic AIO context lock

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
> Use the automatic AIO context acquire/release in scsi_block_realize().
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

I'll let the AIO people reply more thoroughly to this; but this patch is
the case I really like this mechanism for; removing the need for the
goto's and cleanup.

Dave

> ---
>  hw/scsi/scsi-disk.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index e8a547dbb7d..fa2d8543718 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -2605,7 +2605,6 @@ static int get_device_type(SCSIDiskState *s)
>  static void scsi_block_realize(SCSIDevice *dev, Error **errp)
>  {
>      SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
> -    AioContext *ctx;
>      int sg_version;
>      int rc;
>  
> @@ -2620,8 +2619,7 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
>                            "be removed in a future version");
>      }
>  
> -    ctx = blk_get_aio_context(s->qdev.conf.blk);
> -    aio_context_acquire(ctx);
> +    AIO_CONTEXT_ACQUIRE_GUARD(blk_get_aio_context(dev->conf.blk));
>  
>      /* check we are using a driver managing SG_IO (version 3 and after) */
>      rc = blk_ioctl(s->qdev.conf.blk, SG_GET_VERSION_NUM, &sg_version);
> @@ -2630,18 +2628,18 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
>          if (rc != -EPERM) {
>              error_append_hint(errp, "Is this a SCSI device?\n");
>          }
> -        goto out;
> +        return;
>      }
>      if (sg_version < 30000) {
>          error_setg(errp, "scsi generic interface too old");
> -        goto out;
> +        return;
>      }
>  
>      /* get device type from INQUIRY data */
>      rc = get_device_type(s);
>      if (rc < 0) {
>          error_setg(errp, "INQUIRY failed");
> -        goto out;
> +        return;
>      }
>  
>      /* Make a guess for the block size, we'll fix it when the guest sends.
> @@ -2661,9 +2659,6 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
>  
>      scsi_realize(&s->qdev, errp);
>      scsi_generic_read_device_inquiry(&s->qdev);
> -
> -out:
> -    aio_context_release(ctx);
>  }
>  
>  typedef struct SCSIBlockReq {
> -- 
> 2.31.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK