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Message-ID: <CA+M3ks4+REvR=0mLFt-hS4dSfRpx9HLrryb1rfSbYiRSLT2OZQ@mail.gmail.com>
Date: Fri, 29 Mar 2019 16:30:27 +0100
From: Benjamin Gaignard <benjamin.gaignard@...aro.org>
To: "Andrew F. Davis" <afd@...com>
Cc: John Stultz <john.stultz@...aro.org>,
lkml <linux-kernel@...r.kernel.org>,
Laura Abbott <labbott@...hat.com>,
Sumit Semwal <sumit.semwal@...aro.org>,
Liam Mark <lmark@...eaurora.org>,
Pratik Patel <pratikp@...eaurora.org>,
Brian Starkey <Brian.Starkey@....com>,
Vincent Donnefort <Vincent.Donnefort@....com>,
Sudipto Paul <Sudipto.Paul@....com>,
Xu YiPing <xuyiping@...ilicon.com>,
"Chenfeng (puck)" <puck.chen@...ilicon.com>,
butao <butao@...ilicon.com>,
"Xiaqing (A)" <saberlily.xia@...ilicon.com>,
Yudongbin <yudongbin@...ilicon.com>,
Christoph Hellwig <hch@...radead.org>,
Chenbo Feng <fengc@...gle.com>,
Alistair Strachan <astrachan@...gle.com>,
ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC][PATCH 4/6 v3] dma-buf: heaps: Add CMA heap to dmabuf heapss
Le ven. 29 mars 2019 à 16:19, Andrew F. Davis <afd@...com> a écrit :
>
> On 3/29/19 9:44 AM, Benjamin Gaignard wrote:
> > Le ven. 29 mars 2019 à 01:16, John Stultz <john.stultz@...aro.org> a écrit :
> >>
> >> This adds a CMA heap, which allows userspace to allocate
> >> a dma-buf of contiguous memory out of a CMA region.
> >>
> >> This code is an evolution of the Android ION implementation, so
> >> thanks to its original author and maintainters:
> >> Benjamin Gaignard, Laura Abbott, and others!
> >>
> >> Cc: Laura Abbott <labbott@...hat.com>
> >> Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> >> Cc: Sumit Semwal <sumit.semwal@...aro.org>
> >> Cc: Liam Mark <lmark@...eaurora.org>
> >> Cc: Pratik Patel <pratikp@...eaurora.org>
> >> Cc: Brian Starkey <Brian.Starkey@....com>
> >> Cc: Vincent Donnefort <Vincent.Donnefort@....com>
> >> Cc: Sudipto Paul <Sudipto.Paul@....com>
> >> Cc: Andrew F. Davis <afd@...com>
> >> Cc: Xu YiPing <xuyiping@...ilicon.com>
> >> Cc: "Chenfeng (puck)" <puck.chen@...ilicon.com>
> >> Cc: butao <butao@...ilicon.com>
> >> Cc: "Xiaqing (A)" <saberlily.xia@...ilicon.com>
> >> Cc: Yudongbin <yudongbin@...ilicon.com>
> >> Cc: Christoph Hellwig <hch@...radead.org>
> >> 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
> >> v3:
> >> * Switch to inline function for to_cma_heap()
> >> * Minor cleanups suggested by Brian
> >> * Fold in new registration style from Andrew
> >> * Folded in changes from Andrew to use simplified page list
> >> from the heap helpers
> >> ---
> >> drivers/dma-buf/heaps/Kconfig | 8 ++
> >> drivers/dma-buf/heaps/Makefile | 1 +
> >> drivers/dma-buf/heaps/cma_heap.c | 170 +++++++++++++++++++++++++++++++++++++++
> >> 3 files changed, 179 insertions(+)
> >> create mode 100644 drivers/dma-buf/heaps/cma_heap.c
> >>
> >> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> >> index 2050527..a5eef06 100644
> >> --- a/drivers/dma-buf/heaps/Kconfig
> >> +++ b/drivers/dma-buf/heaps/Kconfig
> >> @@ -4,3 +4,11 @@ config DMABUF_HEAPS_SYSTEM
> >> 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.
> >> +
> >> +config DMABUF_HEAPS_CMA
> >> + bool "DMA-BUF CMA Heap"
> >> + depends on DMABUF_HEAPS && DMA_CMA
> >> + help
> >> + Choose this option to enable dma-buf CMA heap. This heap is backed
> >> + by the Contiguous Memory Allocator (CMA). If your system has these
> >> + regions, you should say Y here.
> >> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> >> index d1808ec..6e54cde 100644
> >> --- a/drivers/dma-buf/heaps/Makefile
> >> +++ b/drivers/dma-buf/heaps/Makefile
> >> @@ -1,3 +1,4 @@
> >> # SPDX-License-Identifier: GPL-2.0
> >> obj-y += heap-helpers.o
> >> obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
> >> +obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
> >> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
> >> new file mode 100644
> >> index 0000000..f4485c60
> >> --- /dev/null
> >> +++ b/drivers/dma-buf/heaps/cma_heap.c
> >> @@ -0,0 +1,170 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * DMABUF CMA heap exporter
> >> + *
> >> + * Copyright (C) 2012, 2019 Linaro Ltd.
> >> + * Author: <benjamin.gaignard@...aro.org> for ST-Ericsson.
> >> + */
> >> +
> >> +#include <linux/device.h>
> >> +#include <linux/dma-buf.h>
> >> +#include <linux/dma-heap.h>
> >> +#include <linux/slab.h>
> >> +#include <linux/errno.h>
> >> +#include <linux/err.h>
> >> +#include <linux/cma.h>
> >> +#include <linux/scatterlist.h>
> >> +#include <linux/highmem.h>
> >> +
> >> +#include "heap-helpers.h"
> >> +
> >> +struct cma_heap {
> >> + struct dma_heap *heap;
> >> + struct cma *cma;
> >> +};
> >> +
> >> +static void cma_heap_free(struct heap_helper_buffer *buffer)
> >> +{
> >> + struct cma_heap *cma_heap = dma_heap_get_data(buffer->heap_buffer.heap);
> >> + struct page *pages = buffer->priv_virt;
> >> + unsigned long nr_pages;
> >> +
> >> + nr_pages = buffer->heap_buffer.size >> PAGE_SHIFT;
> >> +
> >> + /* free page list */
> >> + kfree(buffer->pages);
> >> + /* release memory */
> >> + cma_release(cma_heap->cma, pages, nr_pages);
> >> + kfree(buffer);
> >> +}
> >> +
> >> +/* dmabuf heap CMA operations functions */
> >> +static int cma_heap_allocate(struct dma_heap *heap,
> >> + unsigned long len,
> >> + unsigned long flags)
> >> +{
> >> + struct cma_heap *cma_heap = dma_heap_get_data(heap);
> >> + struct heap_helper_buffer *helper_buffer;
> >> + struct page *pages;
> >> + size_t size = PAGE_ALIGN(len);
> >> + unsigned long nr_pages = size >> PAGE_SHIFT;
> >> + unsigned long align = get_order(size);
> >> + DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> >> + struct dma_buf *dmabuf;
> >> + int ret = -ENOMEM;
> >> + pgoff_t pg;
> >> +
> >> + if (align > CONFIG_CMA_ALIGNMENT)
> >> + align = CONFIG_CMA_ALIGNMENT;
> >> +
> >> + helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
> >> + if (!helper_buffer)
> >> + return -ENOMEM;
> >> +
> >> + INIT_HEAP_HELPER_BUFFER(helper_buffer, cma_heap_free);
> >> + helper_buffer->heap_buffer.flags = flags;
> >> + helper_buffer->heap_buffer.heap = heap;
> >> + helper_buffer->heap_buffer.size = len;
> >> +
> >> + pages = cma_alloc(cma_heap->cma, nr_pages, align, false);
> >> + if (!pages)
> >> + goto free_buf;
> >> +
> >> + if (PageHighMem(pages)) {
> >> + unsigned long nr_clear_pages = nr_pages;
> >> + struct page *page = pages;
> >> +
> >> + while (nr_clear_pages > 0) {
> >> + void *vaddr = kmap_atomic(page);
> >> +
> >> + memset(vaddr, 0, PAGE_SIZE);
> >> + kunmap_atomic(vaddr);
> >> + page++;
> >> + nr_clear_pages--;
> >> + }
> >> + } else {
> >> + memset(page_address(pages), 0, size);
> >> + }
> >> +
> >> + helper_buffer->pagecount = nr_pages;
> >> + helper_buffer->pages = kmalloc_array(helper_buffer->pagecount,
> >> + sizeof(*helper_buffer->pages),
> >> + GFP_KERNEL);
> >> + if (!helper_buffer->pages) {
> >> + ret = -ENOMEM;
> >> + goto free_cma;
> >> + }
> >> +
> >> + for (pg = 0; pg < helper_buffer->pagecount; pg++) {
> >> + helper_buffer->pages[pg] = &pages[pg];
> >> + if (!helper_buffer->pages[pg])
> >> + goto free_pages;
> >> + }
> >> +
> >> + /* create the dmabuf */
> >> + exp_info.ops = &heap_helper_ops;
> >> + exp_info.size = len;
> >> + exp_info.flags = O_RDWR;
> >
> > I think that the flags should be provided when requesting the allocation
> > like it is done in DRM or V4L2.
> > For me DMA_HEAP_VALID_FLAGS = (O_CLOEXEC | O_ACCMODE).
> >
>
>
> So something like done in udmabuf?
>
> https://elixir.bootlin.com/linux/v5.1-rc1/source/include/uapi/linux/udmabuf.h#L8
>
> I think that can be arranged.
I have in mind what is done by DRM:
https://elixir.bootlin.com/linux/v5.1-rc1/source/include/uapi/drm/drm.h#L707
V4L2 does the same but without redefine the flags (which is better)
Benjamin
>
> John,
>
> This might be a good reason to move the dma_buf_fd() call below out of
> the heap and back into the core. That way the file exporting flags can
> be common and core handled. I don't think it would complicate the error
> handling any as we only need to dma_buf_put(dmabuf) in the core on
> failure and the heap specific cleanup will happen for us.
>
> Andrew
>
>
> > Benjamin
> >
> > Benjamin
> >
> >> + exp_info.priv = &helper_buffer->heap_buffer;
> >> + dmabuf = dma_buf_export(&exp_info);
> >> + if (IS_ERR(dmabuf)) {
> >> + ret = PTR_ERR(dmabuf);
> >> + goto free_pages;
> >> + }
> >> +
> >> + helper_buffer->heap_buffer.dmabuf = dmabuf;
> >> + helper_buffer->priv_virt = pages;
> >> +
> >> + 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;
> >> +
> >> +free_pages:
> >> + kfree(helper_buffer->pages);
> >> +free_cma:
> >> + cma_release(cma_heap->cma, pages, nr_pages);
> >> +free_buf:
> >> + kfree(helper_buffer);
> >> + return ret;
> >> +}
> >> +
> >> +static struct dma_heap_ops cma_heap_ops = {
> >> + .allocate = cma_heap_allocate,
> >> +};
> >> +
> >> +static int __add_cma_heap(struct cma *cma, void *data)
> >> +{
> >> + struct cma_heap *cma_heap;
> >> + struct dma_heap_export_info exp_info;
> >> +
> >> + cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
> >> + if (!cma_heap)
> >> + return -ENOMEM;
> >> + cma_heap->cma = cma;
> >> +
> >> + exp_info.name = cma_get_name(cma);
> >> + exp_info.ops = &cma_heap_ops;
> >> + exp_info.priv = cma_heap;
> >> +
> >> + cma_heap->heap = dma_heap_add(&exp_info);
> >> + if (IS_ERR(cma_heap->heap)) {
> >> + int ret = PTR_ERR(cma_heap->heap);
> >> +
> >> + kfree(cma_heap);
> >> + return ret;
> >> + }
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int add_cma_heaps(void)
> >> +{
> >> + cma_for_each_area(__add_cma_heap, NULL);
> >> + return 0;
> >> +}
> >> +device_initcall(add_cma_heaps);
> >> --
> >> 2.7.4
> >>
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