On Tue, Jan 19, 2021 at 12:36:40PM -0800, Minchan Kim wrote:

On Tue, Jan 19, 2021 at 10:29:29AM -0800, John Stultz wrote:

quoted

On Tue, Jan 12, 2021 at 5:22 PM Minchan Kim [off-list ref] wrote:

quoted

From: Hyesoo Yu <redacted>

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 (local)

Signed-off-by: Hyesoo Yu <redacted>
Signed-off-by: Hridya Valsaraju <redacted>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---

...

quoted

+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.

quoted

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.

I agree that. It is not good to use heap name directly as cma name.
Let's postfix the name with '-chunk'

Thanks,
Regards.