linux-kernel - Re: [PATCH v6 kernel 3/5] virtio-balloon: speed up inflate/deflate process

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Date:   Fri, 20 Jan 2017 11:48:09 +0000
From:   "Dr. David Alan Gilbert" <dgilbert@...hat.com>
To:     Liang Li <liang.z.li@...el.com>
Cc:     kvm@...r.kernel.org, virtio-dev@...ts.oasis-open.org,
        qemu-devel@...gnu.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, amit.shah@...hat.com,
        dave.hansen@...el.com, cornelia.huck@...ibm.com,
        pbonzini@...hat.com, mst@...hat.com, david@...hat.com,
        aarcange@...hat.com, quintela@...hat.com
Subject: Re: [PATCH v6 kernel 3/5] virtio-balloon: speed up inflate/deflate
 process

* Liang Li (liang.z.li@...el.com) wrote:

<snip>

> +static void free_extended_page_bitmap(struct virtio_balloon *vb)
> +{
> +	int i, bmap_count = vb->nr_page_bmap;
> +
> +	for (i = 1; i < bmap_count; i++) {
> +		kfree(vb->page_bitmap[i]);
> +		vb->page_bitmap[i] = NULL;
> +		vb->nr_page_bmap--;
> +	}
> +}
> +
> +static void kfree_page_bitmap(struct virtio_balloon *vb)
> +{
> +	int i;
> +
> +	for (i = 0; i < vb->nr_page_bmap; i++)
> +		kfree(vb->page_bitmap[i]);
> +}

It might be worth commenting that pair of functions to make it clear
why they are so different; I guess the kfree_page_bitmap
is used just before you free the structure above it so you
don't need to keep the count/pointers updated?

Dave
--
Dr. David Alan Gilbert / dgilbert@...hat.com / Manchester, UK