linux-kernel - Re: [PATCH] virtio_balloon: Fix unused label warning

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Date:   Sun, 16 Feb 2020 00:46:39 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     virtualization@...ts.linux-foundation.org,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        David Hildenbrand <david@...hat.com>
Subject: Re: [PATCH] virtio_balloon: Fix unused label warning

On Mon, Feb 10, 2020 at 10:33:28AM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@...e.de>
> 
> Fix
> 
>   drivers/virtio/virtio_balloon.c: In function ‘virtballoon_probe’:
>   drivers/virtio/virtio_balloon.c:963:1: warning: label ‘out_del_vqs’ defined but not used [-Wunused-label]
>     963 | out_del_vqs:
>         | ^~
> 
> The CONFIG_BALLOON_COMPACTION ifdeffery should enclose it too.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Cc: David Hildenbrand <david@...hat.com>
> ---
>  drivers/virtio/virtio_balloon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 7bfe365d9372..b6ed5f8bccb1 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -959,9 +959,9 @@ static int virtballoon_probe(struct virtio_device *vdev)
>  	iput(vb->vb_dev_info.inode);
>  out_kern_unmount:
>  	kern_unmount(balloon_mnt);
> -#endif
>  out_del_vqs:
>  	vdev->config->del_vqs(vdev);
> +#endif

I noticed the same issue and sent an almost identical patch [1] but I
kept the call to del_vqs outside of the CONFIG_BALLOON_COMPACTION guard
since it seems like that should still be called when that config is
unset, as that was the case before commit 1ad6f58ea936 ("virtio_balloon:
Fix memory leaks on errors in virtballoon_probe()"). Is this patch fully
correct? I am not a virtio expert at all, just noticing from a brief
reading of this function.

[1]: https://lore.kernel.org/lkml/20200216004039.23464-1-natechancellor@gmail.com/

Cheers,
Nathan

>  out_free_vb:
>  	kfree(vb);
>  out:
> -- 
> 2.21.0
>