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Date:   Wed, 6 Mar 2019 17:01:08 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     John Stultz <john.stultz@...aro.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Laura Abbott <labbott@...hat.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Brian Starkey <Brian.Starkey@....com>,
        "Andrew F . Davis" <afd@...com>, Chenbo Feng <fengc@...gle.com>,
        Alistair Strachan <astrachan@...gle.com>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC][PATCH 3/5 v2] dma-buf: heaps: Add system heap to dmabuf heaps

Le mar. 5 mars 2019 à 21:54, John Stultz <john.stultz@...aro.org> a écrit :
>
> This patch adds system heap to the dma-buf heaps framework.
>
> This allows applications to get a page-allocator backed dma-buf
> for non-contiguous memory.
>
> This code is an evolution of the Android ION implementation, so
> thanks to its original authors and maintainters:
>   Rebecca Schultz Zavin, Colin Cross, Laura Abbott, and others!
>
> Cc: Laura Abbott <labbott@...hat.com>
> Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Sumit Semwal <sumit.semwal@...aro.org>
> Cc: Liam Mark <lmark@...eaurora.org>
> Cc: Brian Starkey <Brian.Starkey@....com>
> Cc: Andrew F. Davis <afd@...com>
> Cc: Chenbo Feng <fengc@...gle.com>
> Cc: Alistair Strachan <astrachan@...gle.com>
> Cc: dri-devel@...ts.freedesktop.org
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
> v2:
> * Switch allocate to return dmabuf fd
> * Simplify init code
> * Checkpatch fixups
> * Droped dead system-contig code

just few blank lines to remove.

Reveiwed-by: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> ---
>  drivers/dma-buf/Kconfig             |   2 +
>  drivers/dma-buf/heaps/Kconfig       |   6 ++
>  drivers/dma-buf/heaps/Makefile      |   1 +
>  drivers/dma-buf/heaps/system_heap.c | 132 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 141 insertions(+)
>  create mode 100644 drivers/dma-buf/heaps/Kconfig
>  create mode 100644 drivers/dma-buf/heaps/system_heap.c
>
> diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
> index 09c61db..63c139d 100644
> --- a/drivers/dma-buf/Kconfig
> +++ b/drivers/dma-buf/Kconfig
> @@ -47,4 +47,6 @@ menuconfig DMABUF_HEAPS
>           this allows userspace to allocate dma-bufs that can be shared between
>           drivers.
>
> +source "drivers/dma-buf/heaps/Kconfig"
> +
>  endmenu
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> new file mode 100644
> index 0000000..2050527
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -0,0 +1,6 @@
> +config DMABUF_HEAPS_SYSTEM
> +       bool "DMA-BUF System Heap"
> +       depends on DMABUF_HEAPS
> +       help
> +         Choose this option to enable the system dmabuf heap. The system heap
> +         is backed by pages from the buddy allocator. If in doubt, say Y.
> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> index de49898..d1808ec 100644
> --- a/drivers/dma-buf/heaps/Makefile
> +++ b/drivers/dma-buf/heaps/Makefile
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y                                  += heap-helpers.o
> +obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)      += system_heap.o
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> new file mode 100644
> index 0000000..e001661
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * DMABUF System heap exporter
> + *
> + * Copyright (C) 2011 Google, Inc.
> + * Copyright (C) 2019 Linaro Ltd.
> + */
> +
> +#include <asm/page.h>
> +#include <linux/dma-buf.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dma-heap.h>
> +#include <linux/err.h>
> +#include <linux/highmem.h>
> +#include <linux/mm.h>
> +#include <linux/scatterlist.h>
> +#include <linux/slab.h>
> +
> +#include "heap-helpers.h"
> +
> +
remove blank line
> +struct system_heap {
> +       struct dma_heap heap;
> +};
> +
> +
remove blank line
> +static void system_heap_free(struct heap_helper_buffer *buffer)
> +{
> +       int i;
> +       struct scatterlist *sg;
> +       struct sg_table *table = buffer->sg_table;
> +
> +       for_each_sg(table->sgl, sg, table->nents, i)
> +               __free_page(sg_page(sg));
> +
> +       sg_free_table(table);
> +       kfree(table);
> +       kfree(buffer);
> +}
> +
> +static int system_heap_allocate(struct dma_heap *heap,
> +                               unsigned long len,
> +                               unsigned long flags)
> +{
> +       struct heap_helper_buffer *helper_buffer;
> +       struct sg_table *table;
> +       struct scatterlist *sg;
> +       int i, j;
> +       int npages = PAGE_ALIGN(len) / PAGE_SIZE;
> +       DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +       struct dma_buf *dmabuf;
> +       int ret = -ENOMEM;
> +
> +       helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
> +       if (!helper_buffer)
> +               return -ENOMEM;
> +
> +       INIT_HEAP_HELPER_BUFFER(helper_buffer, system_heap_free);
> +       helper_buffer->heap_buffer.flags = flags;
> +       helper_buffer->heap_buffer.heap = heap;
> +       helper_buffer->heap_buffer.size = len;
> +
> +       table = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
> +       if (!table)
> +               goto err0;
> +
> +       i = sg_alloc_table(table, npages, GFP_KERNEL);
> +       if (i)
> +               goto err1;
> +       for_each_sg(table->sgl, sg, table->nents, i) {
> +               struct page *page;
> +
> +               page = alloc_page(GFP_KERNEL);
> +               if (!page)
> +                       goto err2;
> +               sg_set_page(sg, page, PAGE_SIZE, 0);
> +       }
> +
> +       /* create the dmabuf */
> +       exp_info.ops = &heap_helper_ops;
> +       exp_info.size = len;
> +       exp_info.flags = O_RDWR;
> +       exp_info.priv = &helper_buffer->heap_buffer;
> +       dmabuf = dma_buf_export(&exp_info);
> +       if (IS_ERR(dmabuf)) {
> +               ret = PTR_ERR(dmabuf);
> +               goto err2;
> +       }
> +
> +       helper_buffer->heap_buffer.dmabuf = dmabuf;
> +       helper_buffer->sg_table = table;
> +
> +       ret = dma_buf_fd(dmabuf, O_CLOEXEC);
> +       if (ret < 0) {
> +               dma_buf_put(dmabuf);
> +               /* just return, as put will call release and that will free */
> +               return ret;
> +       }
> +
> +       return ret;
> +
> +err2:
> +       for_each_sg(table->sgl, sg, i, j)
> +               __free_page(sg_page(sg));
> +       sg_free_table(table);
> +err1:
> +       kfree(table);
> +err0:
> +       kfree(helper_buffer);
> +       return -ENOMEM;
> +}
> +
> +
remove blank line
> +static struct dma_heap_ops system_heap_ops = {
> +       .allocate = system_heap_allocate,
> +};
> +
> +static int system_heap_create(void)
> +{
> +       struct system_heap *sys_heap;
> +
> +       sys_heap = kzalloc(sizeof(*sys_heap), GFP_KERNEL);
> +       if (!sys_heap)
> +               return -ENOMEM;
> +       sys_heap->heap.name = "system_heap";
> +       sys_heap->heap.ops = &system_heap_ops;
> +
> +       dma_heap_add(&sys_heap->heap);
> +
> +       return 0;
> +}
> +device_initcall(system_heap_create);
> --
> 2.7.4
>


-- 
Benjamin Gaignard

Graphic Study Group

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