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From: Minchan Kim <minchan@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Hyesoo Yu <hyesoo.yu@samsung.com>,
	david@redhat.com, Michal Hocko <mhocko@suse.com>,
	Suren Baghdasaryan <surenb@google.com>,
	KyongHo Cho <pullip.cho@samsung.com>,
	John Dias <joaodias@google.com>,
	Hridya Valsaraju <hridya@google.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	linux-media <linux-media@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Rob Herring <robh+dt@kernel.org>,
	"moderated list:DMA BUFFER SHARING FRAMEWORK" 
	<linaro-mm-sig@lists.linaro.org>
Subject: Re: [PATCH v3 4/4] dma-buf: heaps: add chunk heap to dmabuf heaps
Date: Tue, 19 Jan 2021 12:36:40 -0800	[thread overview]
Message-ID: <YAdC2J4x/4J9ozkq@google.com> (raw)
In-Reply-To: <CALAqxLWPT8PWYue0h1863NjNxKn_FH0DtoRtArpmmxZ1Ve5xCw@mail.gmail.com>

On Tue, Jan 19, 2021 at 10:29:29AM -0800, John Stultz wrote:
> On Tue, Jan 12, 2021 at 5:22 PM Minchan Kim <minchan@kernel.org> wrote:
> >
> > From: Hyesoo Yu <hyesoo.yu@samsung.com>
> >
> > This patch supports chunk heap that allocates the buffers that
> > arranged into a list a fixed size chunks taken from CMA.
> >
> > The chunk heap driver is bound directly to a reserved_memory
> > node by following Rob Herring's suggestion in [1].
> >
> > [1] https://lore.kernel.org/lkml/20191025225009.50305-2-john.stultz@linaro.org/T/#m3dc63acd33fea269a584f43bb799a876f0b2b45d
> >
> > Signed-off-by: Hyesoo Yu <hyesoo.yu@samsung.com>
> > Signed-off-by: Hridya Valsaraju <hridya@google.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > ---
> ...
> > +static int register_chunk_heap(struct chunk_heap *chunk_heap_info)
> > +{
> > +       struct dma_heap_export_info exp_info;
> > +
> > +       exp_info.name = cma_get_name(chunk_heap_info->cma);
> 
> One potential issue here, you're setting the name to the same as the
> CMA name. Since the CMA heap uses the CMA name, if one chunk was
> registered as a chunk heap but also was the default CMA area, it might
> be registered twice. But since both would have the same name it would
> be an initialization race as to which one "wins".

Good point. Maybe someone might want to use default CMA area for
both cma_heap and chunk_heap. I cannot come up with ideas why we
should prohibit it atm.

> 
> So maybe could you postfix the CMA name with "-chunk" or something?

Hyesoo, Any opinion?
Unless you have something other idea, let's fix it in next version.

  reply	other threads:[~2021-01-19 20:42 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-13  1:21 [PATCH v3 0/4] Chunk Heap Support on DMA-HEAP Minchan Kim
2021-01-13  1:21 ` [PATCH v3 1/4] mm: cma: introduce gfp flag in cma_alloc instead of no_warn Minchan Kim
2021-01-20 21:08   ` Suren Baghdasaryan
2021-01-13  1:21 ` [PATCH v3 2/4] mm: failfast mode with __GFP_NORETRY in alloc_contig_range Minchan Kim
2021-01-13  8:39   ` David Hildenbrand
2021-01-14 18:04     ` Minchan Kim
2021-01-13  1:21 ` [PATCH v3 3/4] dt-bindings: reserved-memory: Make DMA-BUF CMA heap DT-configurable Minchan Kim
2021-01-13 15:45   ` Rob Herring
2021-01-13 17:30     ` Hridya Valsaraju
2021-01-13 17:30       ` Hridya Valsaraju
2021-01-14 14:01   ` Rob Herring
2021-01-14 19:49     ` Hridya Valsaraju
2021-01-14 19:49       ` Hridya Valsaraju
2021-01-13  1:21 ` [PATCH v3 4/4] dma-buf: heaps: add chunk heap to dmabuf heaps Minchan Kim
2021-01-13  3:11   ` kernel test robot
2021-01-13  3:11     ` kernel test robot
2021-01-14  1:04     ` Minchan Kim
2021-01-14  1:04       ` Minchan Kim
2021-01-13  3:38   ` Randy Dunlap
2021-01-14  1:04     ` Minchan Kim
2021-01-13  6:25   ` kernel test robot
2021-01-13  6:25     ` kernel test robot
2021-01-19 15:51   ` Minchan Kim
2021-01-19 18:29   ` John Stultz
2021-01-19 18:29     ` John Stultz
2021-01-19 20:36     ` Minchan Kim [this message]
2021-01-19 20:36       ` Minchan Kim
2021-01-20  3:32       ` Hyesoo Yu
2021-01-20  3:32         ` Hyesoo Yu
2021-01-20 20:53         ` Suren Baghdasaryan
2021-01-20 20:53           ` Suren Baghdasaryan

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