linux-kernel - Re: [PATCH v2] udmabuf: add vmap method to udmabuf

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Message-ID: <20221114052944.GA7264@thinkpad-p72>
Date:   Mon, 14 Nov 2022 06:29:44 +0100
From:   Lukasz Wiecaszek <lukasz.wiecaszek@...glemail.com>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     Lukasz Wiecaszek <lukasz.wiecaszek@...glemail.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        kernel test robot <lkp@...el.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] udmabuf: add vmap method to udmabuf_ops

On Sun, Nov 13, 2022 at 07:35:20PM +0300, Dmitry Osipenko wrote:
> On 11/13/22 18:05, Lukasz Wiecaszek wrote:
> > +static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
> > +{
> > +	struct udmabuf *ubuf = buf->priv;
> > +
> > +	if (!ubuf->vaddr) {
> > +		ubuf->vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
> > +		if (!ubuf->vaddr)
> > +			return -EINVAL;
> > +	}
> 
> Create a new mapping on each vmap_udmabuf() and add the corresponding
> vunmap.
> 
> Otherwise persistent vmapping shall be released together with udmabuf.
> It doesn't look that persistent vmapping is needed for udmabufs.
> 
> -- 
> Best regards,
> Dmitry

Right. Thanks for review and remarks. Adding vunmap sounds reasonable to
me. Will add it somehow this week.

Regards,
Lukasz