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References: <20210121175502.274391-1-minchan@kernel.org> <20210121175502.274391-5-minchan@kernel.org>
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From:   John Stultz <john.stultz@linaro.org>
Date:   Mon, 25 Jan 2021 23:32:57 -0800
Message-ID: <CALAqxLWJDo=pM8bvt9YWrzJ+VyK5gojoL-v7ch1fQC=cjGwJOw@mail.gmail.com>
Subject: Re: [PATCH v4 4/4] dma-buf: heaps: add chunk heap to dmabuf heaps
To:     Minchan Kim <minchan@kernel.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>
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On Thu, Jan 21, 2021 at 9:55 AM Minchan Kim <minchan@kernel.org> wrote:

Hey Minchan,
  Thanks for sending this out! I'm still working through testing with
this patch set, so I may have some more feedback tomorrow, but a few
quick items I did hit below.

> +
> +#define CHUNK_PREFIX "chunk-"
> +
> +static int register_chunk_heap(struct chunk_heap *chunk_heap_info)
> +{
> +       struct dma_heap_export_info exp_info;
> +       const char *name = cma_get_name(chunk_heap_info->cma);
> +       size_t len = strlen(CHUNK_PREFIX) + strlen(name) + 1;
> +       char *buf = kmalloc(len, GFP_KERNEL);
> +
> +       if (!buf)
> +               return -ENOMEM;
> +
> +       sprintf(buf, CHUNK_PREFIX"%s", cma_get_name(chunk_heap_info->cma));
> +       buf[len] = '\0';
> +
> +       exp_info.name = buf;
> +       exp_info.name = cma_get_name(chunk_heap_info->cma);

I think you intended to delete this line, as it's overwriting your
prefixed name.

> +       exp_info.ops = &chunk_heap_ops;
> +       exp_info.priv = chunk_heap_info;
> +
> +       chunk_heap_info->heap = dma_heap_add(&exp_info);
> +       if (IS_ERR(chunk_heap_info->heap)) {
> +               kfree(buf);
> +               return PTR_ERR(chunk_heap_info->heap);
> +       }
> +
> +       return 0;
> +}
> +
> +static int __init chunk_heap_init(void)
> +{
> +       unsigned int i;
> +
> +       for (i = 0; i < chunk_heap_count; i++)
> +               register_chunk_heap(&chunk_heaps[i]);
> +
> +       return 0;
> +}
> +module_init(chunk_heap_init);
> +
> +#ifdef CONFIG_OF_EARLY_FLATTREE
> +
> +static int __init dmabuf_chunk_heap_area_init(struct reserved_mem *rmem)
> +{
> +       int ret;
> +       struct cma *cma;
> +       struct chunk_heap *chunk_heap_info;
> +       const __be32 *chunk_order;
> +
> +       phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
> +       phys_addr_t mask = align - 1;
> +
> +       if ((rmem->base & mask) || (rmem->size & mask)) {
> +               pr_err("Incorrect alignment for CMA region\n");
> +               return -EINVAL;

Passing this check can be tough if you're using dynamically assigned
rmem, so it might be helpful for debugging to print the base/size/mask
values?

thanks
-john