linux-kernel - Re: [PATCH] virtio: Directly use ida_alloc_range()/ida

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Date:   Wed, 8 Jun 2022 21:06:03 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Deming Wang <wangdeming@...pur.com>, mst@...hat.com,
        jasowang@...hat.com
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] virtio: Directly use ida_alloc_range()/ida_free()

Hi,

Le 08/06/2022 à 08:08, Deming Wang a écrit :
> Use ida_alloc_range()/ida_free() instead of deprecated
> ida_simple_get()/ida_simple_remove() .
> 
> Signed-off-by: Deming Wang <wangdeming@...pur.com>
> ---
>   drivers/vhost/vdpa.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 935a1d0ddb97..384049cfca8d 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -1293,7 +1293,7 @@ static void vhost_vdpa_release_dev(struct device *device)
>   	struct vhost_vdpa *v =
>   	       container_of(device, struct vhost_vdpa, dev);
>   
> -	ida_simple_remove(&vhost_vdpa_ida, v->minor);
> +	ida_free(&vhost_vdpa_ida, v->minor);
>   	kfree(v->vqs);
>   	kfree(v);
>   }
> @@ -1316,8 +1316,7 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
>   	if (!v)
>   		return -ENOMEM;
>   
> -	minor = ida_simple_get(&vhost_vdpa_ida, 0,
> -			       VHOST_VDPA_DEV_MAX, GFP_KERNEL);
> +	minor = ida_alloc_range(&vhost_vdpa_ida, 0, VHOST_VDPA_DEV_MAX - 1, GFP_KERNEL);

ida_alloc_max() would be better here. It is less verbose.

An explanation in the commit log of why the -1 is needed would also help 
reviewer/maintainer, IMHO.

It IS correct, but it is not that obvious without looking at 
ida_simple_get() and ida_alloc_range().

CJ


>   	if (minor < 0) {
>   		kfree(v);
>   		return minor;