linux-kernel - Re: [PATCH v2] dma-contiguous: define proper name for global cma region

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Message-ID: <CAOuPNLjnfq1JefngtNrg0Q+JdMTSRz+eEqxGQJFfx9+af+k9WA@mail.gmail.com>
Date:   Tue, 1 Aug 2023 22:42:42 +0530
From:   Pintu Agarwal <pintu.ping@...il.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Pintu Kumar <quic_pintu@...cinc.com>, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        m.szyprowski@...sung.com, robin.murphy@....com,
        iommu@...ts.linux.dev, Sumit Semwal <sumit.semwal@...aro.org>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Liam Mark <lmark@...eaurora.org>,
        Laura Abbott <labbott@...hat.com>,
        Brian Starkey <Brian.Starkey@....com>,
        John Stultz <jstultz@...gle.com>,
        Christian König <christian.koenig@....com>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH v2] dma-contiguous: define proper name for global cma region

Hi Christoph,
Thank you so much for your review and comments.

On Mon, 31 Jul 2023 at 16:51, Christoph Hellwig <hch@....de> wrote:
>
> Hi Pintu,
>
> On Sat, Jul 29, 2023 at 08:05:15AM +0530, Pintu Kumar wrote:
> > The current global cma region name defined as "reserved"
> > which is misleading, creates confusion and too generic.
> >
> > Also, the default cma allocation happens from global cma region,
> > so, if one has to figure out all allocations happening from
> > global cma region, this seems easier.
> >
> > Thus, change the name from "reserved" to "global-cma-region".
>
> I agree that reserved is not a very useful name.  Unfortuately the
> name of the region leaks to userspace through cma_heap.
>
> So I think we need prep patches to hardcode "reserved" in
> add_default_cma_heap first, and then remove the cma_get_name
> first.

Sorry, but I could not fully understand your comments.
Can you please elaborate a little more what changes are required in
cma_heap if we change "reserved" to "global-cma-region" ?
You mean to say there are userspace tools that rely on this "reserved"
naming for global cma ?