Re: [Qemu-devel] [PATCH] blockdev: fix error handling in do_open_tray

[Eric Blake <eblake@redhat.com>]

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On 06/03/2016 12:20 PM, clord@redhat.com wrote:
> From: Colin Lord <clord@redhat.com>

You may want to update your ~/.gitconfig to set sendemail.from to list
your name in the same manner in which you add S-o-b.  (Not strictly a
problem, as 'git am' does the right thing either way, but it will avoid
this secondary From: line in patch mails you send)

> 
> Returns negative error codes and accompanying error messages in cases where
> the device has no tray or the tray is locked and isn't forced open. This
> extra information should result in better flexibility in functions that
> call do_open_tray.
> 
> Signed-off-by: Colin Lord <clord@redhat.com>
> ---
>  blockdev.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 717785e..d10ab35 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -2286,17 +2286,14 @@ void qmp_eject(const char *device, bool has_force, bool force, Error **errp)
>      }
>  
>      rc = do_open_tray(device, force, &local_err);
> -    if (local_err) {
> +    if (rc == -ENOSYS) {
> +        error_free(local_err);
> +        local_err = NULL;
> +    } else if (local_err) {
>          error_propagate(errp, local_err);
>          return;
>      }
>  
> -    if (rc == EINPROGRESS) {
> -        error_setg(errp, "Device '%s' is locked and force was not specified, "
> -                   "wait for tray to open and try again", device);
> -        return;
> -    }
> -

So in this function, we still ignore ENOSYS, and the EINPROGRESS error
message has now moved to the helper function. No change in overall
behavior, good.

>      qmp_x_blockdev_remove_medium(device, errp);
>  }
>  
> @@ -2348,8 +2345,8 @@ static int do_open_tray(const char *device, bool force, Error **errp)
>      }
>  
>      if (!blk_dev_has_tray(blk)) {
> -        /* Ignore this command on tray-less devices */
> -        return ENOSYS;
> +        error_setg(errp, "Device '%s' does not have a tray", device);
> +        return -ENOSYS;
>      }
>  
>      if (blk_dev_is_tray_open(blk)) {
> @@ -2366,7 +2363,9 @@ static int do_open_tray(const char *device, bool force, Error **errp)
>      }
>  
>      if (locked && !force) {
> -        return EINPROGRESS;
> +        error_setg(errp, "Device '%s' is locked and force was not specified, "
> +                   "wait for tray to open and try again", device);
> +        return -EINPROGRESS;

And here, we always return negative error.

Oops, you forgot to update the comments before this function, describing
its new (simpler) semantics.

>      }
>  
>      return 0;
> @@ -2375,10 +2374,18 @@ static int do_open_tray(const char *device, bool force, Error **errp)
>  void qmp_blockdev_open_tray(const char *device, bool has_force, bool force,
>                              Error **errp)
>  {
> +    Error *local_err = NULL;
> +    int rc;
> +
>      if (!has_force) {
>          force = false;
>      }
> -    do_open_tray(device, force, errp);
> +    rc = do_open_tray(device, force, &local_err);
> +    if (local_err && (rc == -EINPROGRESS || rc == -ENOSYS)) {

The 'local_err &&' portion of the conditional is dead code. You could go
straight into the comparison of particular rc values.

> +        error_free(local_err);
> +    } else {
> +        error_propagate(errp, local_err);
> +    }
>  }
>  
>  void qmp_blockdev_close_tray(const char *device, Error **errp)
> 

This appears to be your first qemu patch - congratulations, and welcome
to the community.

Looking forward to v2.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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