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From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 30 Mar 2010 15:53:29 +1030
References: <4BAAF5CA.2010401@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH 4/4] Add virtio disk identification support
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To: john cooper <john.cooper@redhat.com>
Cc: Marc Haber <mh+qemu-devel@zugschlus.de>, qemu-devel@nongnu.org

On Thu, 25 Mar 2010 04:04:02 pm john cooper wrote:
> Return serial string to the guest application via
> ioctl driver call.

This is quite nice.  Minor nits:

> +	if (cmd == 'VBID') {
> +		void *usr_data = (void __user *)data;

void __user *usr_data;

> +		char *id_str;
> +		int err;
> +
> +		if (!(id_str = kmalloc(VIRTIO_BLK_ID_BYTES, GFP_KERNEL)))
> +			err = -ENOMEM;
> +		else if ((err = virtblk_get_id(disk, id_str)))
> +			;
> +		else if (copy_to_user(usr_data, id_str, VIRTIO_BLK_ID_BYTES))
> +			err = -EFAULT;
> +		if (id_str)
> +			kfree(id_str);
> +		return err;
> +	}

We can't put the id_str on the stack?  Makes it even simpler :)

Cheers,
Rusty.