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Message-ID: <72cfdad2-ba33-4b90-acfa-7e50b8d9ec51@vivo.com>
Date: Fri, 12 Jul 2024 09:59:54 +0800
From: Huan Yang <link@...o.com>
To: Christian König <christian.koenig@....com>,
Sumit Semwal <sumit.semwal@...aro.org>,
Benjamin Gaignard <benjamin.gaignard@...labora.com>,
Brian Starkey <Brian.Starkey@....com>, John Stultz <jstultz@...gle.com>,
"T.J. Mercier" <tjmercier@...gle.com>, linux-media@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
linux-kernel@...r.kernel.org
Cc: opensource.kernel@...o.com
Subject: Re: [PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE
framework
Hi Christian,
在 2024/7/11 19:39, Christian König 写道:
> Am 11.07.24 um 11:18 schrieb Huan Yang:
>> Hi Christian,
>>
>> Thanks for your reply.
>>
>> 在 2024/7/11 17:00, Christian König 写道:
>>> Am 11.07.24 um 09:42 schrieb Huan Yang:
>>>> Some user may need load file into dma-buf, current
>>>> way is:
>>>> 1. allocate a dma-buf, get dma-buf fd
>>>> 2. mmap dma-buf fd into vaddr
>>>> 3. read(file_fd, vaddr, fsz)
>>>> This is too heavy if fsz reached to GB.
>>>
>>> You need to describe a bit more why that is to heavy. I can only
>>> assume you need to save memory bandwidth and avoid the extra copy
>>> with the CPU.
>>
>> Sorry for the oversimplified explanation. But, yes, you're right, we
>> want to avoid this.
>>
>> As we are dealing with embedded devices, the available memory and
>> computing power for users are usually limited.(The maximum available
>> memory is currently
>>
>> 24GB, typically ranging from 8-12GB. )
>>
>> Also, the CPU computing power is also usually in short supply, due to
>> limited battery capacity and limited heat dissipation capabilities.
>>
>> So, we hope to avoid ineffective paths as much as possible.
>>
>>>
>>>> This patch implement a feature called DMA_HEAP_IOCTL_ALLOC_READ_FILE.
>>>> User need to offer a file_fd which you want to load into dma-buf,
>>>> then,
>>>> it promise if you got a dma-buf fd, it will contains the file content.
>>>
>>> Interesting idea, that has at least more potential than trying to
>>> enable direct I/O on mmap()ed DMA-bufs.
>>>
>>> The approach with the new IOCTL might not work because it is a very
>>> specialized use case.
>>
>> Thank you for your advice. maybe the "read file" behavior can be
>> attached to an existing allocation?
>
> The point is there are already system calls to do something like that.
>
> See copy_file_range()
> (https://man7.org/linux/man-pages/man2/copy_file_range.2.html)
> and send_file()
> (https://man7.org/linux/man-pages/man2/sendfile.2.html).
That's helpfull to learn it, thanks.
In terms of only DMA-BUF supporting direct I/O,
copy_file_range/send_file may help to achieve this functionality.
However, my patchset also aims to achieve parallel copying of file
contents while allocating the DMA-BUF, which is something that the
current set of calls may not be able to accomplish.
Perhaps simply returning the DMA-BUF file descriptor and then
implementing copy_file_range, while populating the memory and content
during the copy process, could achieve this? At present, it seems that
it will be quite complex - We need to ensure that only the returned
DMA-BUF file descriptor will fail in case of memory not fill, like mmap,
vmap, attach, and so on.
>
> What we probably could do is to internally optimize those.
>
>> I am currently creating a new ioctl to remind the user that memory is
>> being allocated and read, and I am also unsure
>>
>> whether it is appropriate to add additional parameters to the
>> existing allocate behavior.
>>
>> Please, give me more suggestion. Thanks.
>>
>>>
>>> But IIRC there was a copy_file_range callback in the file_operations
>>> structure you could use for that. I'm just not sure when and how
>>> that's used with the copy_file_range() system call.
>>
>> Sorry, I'm not familiar with this, but I will look into it. However,
>> this type of callback function is not currently implemented when
>> exporting
>>
>> the dma_buf file, which means that I need to implement the callback
>> for it?
>
> If I'm not completely mistaken the copy_file_range, splice_read and
> splice_write callbacks on the struct file_operations
> (https://elixir.bootlin.com/linux/v6.10-rc7/source/include/linux/fs.h#L1999).
>
> Can be used to implement what you want to do.
Yes.
>
> Regards,
> Christian.
>
>>
>>>
>>> Regards,
>>> Christian.
>>>
>>>>
>>>> Notice, file_fd depends on user how to open this file. So, both buffer
>>>> I/O and Direct I/O is supported.
>>>>
>>>> Signed-off-by: Huan Yang <link@...o.com>
>>>> ---
>>>> drivers/dma-buf/dma-heap.c | 525
>>>> +++++++++++++++++++++++++++++++++-
>>>> include/linux/dma-heap.h | 57 +++-
>>>> include/uapi/linux/dma-heap.h | 32 +++
>>>> 3 files changed, 611 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
>>>> index 2298ca5e112e..abe17281adb8 100644
>>>> --- a/drivers/dma-buf/dma-heap.c
>>>> +++ b/drivers/dma-buf/dma-heap.c
>>>> @@ -15,9 +15,11 @@
>>>> #include <linux/list.h>
>>>> #include <linux/slab.h>
>>>> #include <linux/nospec.h>
>>>> +#include <linux/highmem.h>
>>>> #include <linux/uaccess.h>
>>>> #include <linux/syscalls.h>
>>>> #include <linux/dma-heap.h>
>>>> +#include <linux/vmalloc.h>
>>>> #include <uapi/linux/dma-heap.h>
>>>> #define DEVNAME "dma_heap"
>>>> @@ -43,12 +45,462 @@ struct dma_heap {
>>>> struct cdev heap_cdev;
>>>> };
>>>> +/**
>>>> + * struct dma_heap_file - wrap the file, read task for dma_heap
>>>> allocate use.
>>>> + * @file: file to read from.
>>>> + *
>>>> + * @cred: kthread use, user cred copy to use for the read.
>>>> + *
>>>> + * @max_batch: maximum batch size to read, if collect match
>>>> batch,
>>>> + * trigger read, default 128MB, must below file size.
>>>> + *
>>>> + * @fsz: file size.
>>>> + *
>>>> + * @direct: use direct IO?
>>>> + */
>>>> +struct dma_heap_file {
>>>> + struct file *file;
>>>> + struct cred *cred;
>>>> + size_t max_batch;
>>>> + size_t fsz;
>>>> + bool direct;
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct dma_heap_file_work - represents a dma_heap file read
>>>> real work.
>>>> + * @vaddr: contigous virtual address alloc by vmap, file
>>>> read need.
>>>> + *
>>>> + * @start_size: file read start offset, same to
>>>> @dma_heap_file_task->roffset.
>>>> + *
>>>> + * @need_size: file read need size, same to
>>>> @dma_heap_file_task->rsize.
>>>> + *
>>>> + * @heap_file: file wrapper.
>>>> + *
>>>> + * @list: child node of @dma_heap_file_control->works.
>>>> + *
>>>> + * @refp: same @dma_heap_file_task->ref, if end of read,
>>>> put ref.
>>>> + *
>>>> + * @failp: if any work io failed, set it true, pointp
>>>> @dma_heap_file_task->fail.
>>>> + */
>>>> +struct dma_heap_file_work {
>>>> + void *vaddr;
>>>> + ssize_t start_size;
>>>> + ssize_t need_size;
>>>> + struct dma_heap_file *heap_file;
>>>> + struct list_head list;
>>>> + atomic_t *refp;
>>>> + bool *failp;
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct dma_heap_file_task - represents a dma_heap file read
>>>> process
>>>> + * @ref: current file work counter, if zero, allocate and read
>>>> + * done.
>>>> + *
>>>> + * @roffset: last read offset, current prepared work' begin
>>>> file
>>>> + * start offset.
>>>> + *
>>>> + * @rsize: current allocated page size use to read, if
>>>> reach rbatch,
>>>> + * trigger commit.
>>>> + *
>>>> + * @rbatch: current prepared work's batch, below
>>>> @dma_heap_file's
>>>> + * batch.
>>>> + *
>>>> + * @heap_file: current dma_heap_file
>>>> + *
>>>> + * @parray: used for vmap, size is @dma_heap_file's batch's
>>>> number
>>>> + * pages.(this is maximum). Due to single thread file
>>>> read,
>>>> + * one page array reuse each work prepare is OK.
>>>> + * Each index in parray is PAGE_SIZE.(vmap need)
>>>> + *
>>>> + * @pindex: current allocated page filled in @parray's index.
>>>> + *
>>>> + * @fail: any work failed when file read?
>>>> + *
>>>> + * dma_heap_file_task is the production of file read, will prepare
>>>> each work
>>>> + * during allocate dma_buf pages, if match current batch, then
>>>> trigger commit
>>>> + * and prepare next work. After all batch queued, user going on
>>>> prepare dma_buf
>>>> + * and so on, but before return dma_buf fd, need to wait file read
>>>> end and
>>>> + * check read result.
>>>> + */
>>>> +struct dma_heap_file_task {
>>>> + atomic_t ref;
>>>> + size_t roffset;
>>>> + size_t rsize;
>>>> + size_t rbatch;
>>>> + struct dma_heap_file *heap_file;
>>>> + struct page **parray;
>>>> + unsigned int pindex;
>>>> + bool fail;
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct dma_heap_file_control - global control of dma_heap file
>>>> read.
>>>> + * @works: @dma_heap_file_work's list head.
>>>> + *
>>>> + * @lock: only lock for @works.
>>>> + *
>>>> + * @threadwq: wait queue for @work_thread, if commit work,
>>>> @work_thread
>>>> + * wakeup and read this work's file contains.
>>>> + *
>>>> + * @workwq: used for main thread wait for file read end, if
>>>> allocation
>>>> + * end before file read. @dma_heap_file_task ref effect
>>>> this.
>>>> + *
>>>> + * @work_thread: file read kthread. the dma_heap_file_task
>>>> work's consumer.
>>>> + *
>>>> + * @heap_fwork_cachep: @dma_heap_file_work's cachep, it's
>>>> alloc/free frequently.
>>>> + *
>>>> + * @nr_work: global number of how many work committed.
>>>> + */
>>>> +struct dma_heap_file_control {
>>>> + struct list_head works;
>>>> + spinlock_t lock;
>>>> + wait_queue_head_t threadwq;
>>>> + wait_queue_head_t workwq;
>>>> + struct task_struct *work_thread;
>>>> + struct kmem_cache *heap_fwork_cachep;
>>>> + atomic_t nr_work;
>>>> +};
>>>> +
>>>> +static struct dma_heap_file_control *heap_fctl;
>>>> static LIST_HEAD(heap_list);
>>>> static DEFINE_MUTEX(heap_list_lock);
>>>> static dev_t dma_heap_devt;
>>>> static struct class *dma_heap_class;
>>>> static DEFINE_XARRAY_ALLOC(dma_heap_minors);
>>>> +/**
>>>> + * map_pages_to_vaddr - map each scatter page into contiguous
>>>> virtual address.
>>>> + * @heap_ftask: prepared and need to commit's work.
>>>> + *
>>>> + * Cached pages need to trigger file read, this function map each
>>>> scatter page
>>>> + * into contiguous virtual address, so that file read can easy use.
>>>> + * Now that we get vaddr page, cached pages can return to original
>>>> user, so we
>>>> + * will not effect dma-buf export even if file read not end.
>>>> + */
>>>> +static void *map_pages_to_vaddr(struct dma_heap_file_task
>>>> *heap_ftask)
>>>> +{
>>>> + return vmap(heap_ftask->parray, heap_ftask->pindex, VM_MAP,
>>>> + PAGE_KERNEL);
>>>> +}
>>>> +
>>>> +bool dma_heap_prepare_file_read(struct dma_heap_file_task
>>>> *heap_ftask,
>>>> + struct page *page)
>>>> +{
>>>> + struct page **array = heap_ftask->parray;
>>>> + int index = heap_ftask->pindex;
>>>> + int num = compound_nr(page), i;
>>>> + unsigned long sz = page_size(page);
>>>> +
>>>> + heap_ftask->rsize += sz;
>>>> + for (i = 0; i < num; ++i)
>>>> + array[index++] = &page[i];
>>>> + heap_ftask->pindex = index;
>>>> +
>>>> + return heap_ftask->rsize >= heap_ftask->rbatch;
>>>> +}
>>>> +
>>>> +static struct dma_heap_file_work *
>>>> +init_file_work(struct dma_heap_file_task *heap_ftask)
>>>> +{
>>>> + struct dma_heap_file_work *heap_fwork;
>>>> + struct dma_heap_file *heap_file = heap_ftask->heap_file;
>>>> +
>>>> + if (READ_ONCE(heap_ftask->fail))
>>>> + return NULL;
>>>> +
>>>> + heap_fwork = kmem_cache_alloc(heap_fctl->heap_fwork_cachep,
>>>> GFP_KERNEL);
>>>> + if (unlikely(!heap_fwork))
>>>> + return NULL;
>>>> +
>>>> + heap_fwork->vaddr = map_pages_to_vaddr(heap_ftask);
>>>> + if (unlikely(!heap_fwork->vaddr)) {
>>>> + kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);
>>>> + return NULL;
>>>> + }
>>>> +
>>>> + heap_fwork->heap_file = heap_file;
>>>> + heap_fwork->start_size = heap_ftask->roffset;
>>>> + heap_fwork->need_size = heap_ftask->rsize;
>>>> + heap_fwork->refp = &heap_ftask->ref;
>>>> + heap_fwork->failp = &heap_ftask->fail;
>>>> + atomic_inc(&heap_ftask->ref);
>>>> + return heap_fwork;
>>>> +}
>>>> +
>>>> +static void destroy_file_work(struct dma_heap_file_work *heap_fwork)
>>>> +{
>>>> + vunmap(heap_fwork->vaddr);
>>>> + atomic_dec(heap_fwork->refp);
>>>> + wake_up(&heap_fctl->workwq);
>>>> +
>>>> + kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);
>>>> +}
>>>> +
>>>> +int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask)
>>>> +{
>>>> + struct dma_heap_file_work *heap_fwork =
>>>> init_file_work(heap_ftask);
>>>> + struct page *last = NULL;
>>>> + struct dma_heap_file *heap_file = heap_ftask->heap_file;
>>>> + size_t start = heap_ftask->roffset;
>>>> + struct file *file = heap_file->file;
>>>> + size_t fsz = heap_file->fsz;
>>>> +
>>>> + if (unlikely(!heap_fwork))
>>>> + return -ENOMEM;
>>>> +
>>>> + /**
>>>> + * If file size is not page aligned, direct io can't process
>>>> the tail.
>>>> + * So, if reach to tail, remain the last page use buffer read.
>>>> + */
>>>> + if (heap_file->direct && start + heap_ftask->rsize > fsz) {
>>>> + heap_fwork->need_size -= PAGE_SIZE;
>>>> + last = heap_ftask->parray[heap_ftask->pindex - 1];
>>>> + }
>>>> +
>>>> + spin_lock(&heap_fctl->lock);
>>>> + list_add_tail(&heap_fwork->list, &heap_fctl->works);
>>>> + spin_unlock(&heap_fctl->lock);
>>>> + atomic_inc(&heap_fctl->nr_work);
>>>> +
>>>> + wake_up(&heap_fctl->threadwq);
>>>> +
>>>> + if (last) {
>>>> + char *buf, *pathp;
>>>> + ssize_t err;
>>>> + void *buffer;
>>>> +
>>>> + buf = kmalloc(PATH_MAX, GFP_KERNEL);
>>>> + if (unlikely(!buf))
>>>> + return -ENOMEM;
>>>> +
>>>> + start = PAGE_ALIGN_DOWN(fsz);
>>>> +
>>>> + pathp = file_path(file, buf, PATH_MAX);
>>>> + if (IS_ERR(pathp)) {
>>>> + kfree(buf);
>>>> + return PTR_ERR(pathp);
>>>> + }
>>>> +
>>>> + buffer = kmap_local_page(last); // use page's kaddr.
>>>> + err = kernel_read_file_from_path(pathp, start, &buffer,
>>>> + fsz - start, &fsz,
>>>> + READING_POLICY);
>>>> + kunmap_local(buffer);
>>>> + kfree(buf);
>>>> + if (err < 0) {
>>>> + pr_err("failed to use buffer kernel_read_file %s,
>>>> err=%ld, [%ld, %ld], f_sz=%ld\n",
>>>> + pathp, err, start, fsz, fsz);
>>>> +
>>>> + return err;
>>>> + }
>>>> + }
>>>> +
>>>> + heap_ftask->roffset += heap_ftask->rsize;
>>>> + heap_ftask->rsize = 0;
>>>> + heap_ftask->pindex = 0;
>>>> + heap_ftask->rbatch = min_t(size_t,
>>>> + PAGE_ALIGN(fsz) - heap_ftask->roffset,
>>>> + heap_ftask->rbatch);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +bool dma_heap_wait_for_file_read(struct dma_heap_file_task
>>>> *heap_ftask)
>>>> +{
>>>> + wait_event_freezable(heap_fctl->workwq,
>>>> + atomic_read(&heap_ftask->ref) == 0);
>>>> + return heap_ftask->fail;
>>>> +}
>>>> +
>>>> +bool dma_heap_destroy_file_read(struct dma_heap_file_task
>>>> *heap_ftask)
>>>> +{
>>>> + bool fail;
>>>> +
>>>> + dma_heap_wait_for_file_read(heap_ftask);
>>>> + fail = heap_ftask->fail;
>>>> + kvfree(heap_ftask->parray);
>>>> + kfree(heap_ftask);
>>>> + return fail;
>>>> +}
>>>> +
>>>> +struct dma_heap_file_task *
>>>> +dma_heap_declare_file_read(struct dma_heap_file *heap_file)
>>>> +{
>>>> + struct dma_heap_file_task *heap_ftask =
>>>> + kzalloc(sizeof(*heap_ftask), GFP_KERNEL);
>>>> + if (unlikely(!heap_ftask))
>>>> + return NULL;
>>>> +
>>>> + /**
>>>> + * Batch is the maximum size which we prepare work will meet.
>>>> + * So, direct alloc this number's page array is OK.
>>>> + */
>>>> + heap_ftask->parray = kvmalloc_array(heap_file->max_batch >>
>>>> PAGE_SHIFT,
>>>> + sizeof(struct page *), GFP_KERNEL);
>>>> + if (unlikely(!heap_ftask->parray))
>>>> + goto put;
>>>> +
>>>> + heap_ftask->heap_file = heap_file;
>>>> + heap_ftask->rbatch = heap_file->max_batch;
>>>> + return heap_ftask;
>>>> +put:
>>>> + kfree(heap_ftask);
>>>> + return NULL;
>>>> +}
>>>> +
>>>> +static void __work_this_io(struct dma_heap_file_work *heap_fwork)
>>>> +{
>>>> + struct dma_heap_file *heap_file = heap_fwork->heap_file;
>>>> + struct file *file = heap_file->file;
>>>> + ssize_t start = heap_fwork->start_size;
>>>> + ssize_t size = heap_fwork->need_size;
>>>> + void *buffer = heap_fwork->vaddr;
>>>> + const struct cred *old_cred;
>>>> + ssize_t err;
>>>> +
>>>> + // use real task's cred to read this file.
>>>> + old_cred = override_creds(heap_file->cred);
>>>> + err = kernel_read_file(file, start, &buffer, size,
>>>> &heap_file->fsz,
>>>> + READING_POLICY);
>>>> + if (err < 0) {
>>>> + pr_err("use kernel_read_file, err=%ld, [%ld, %ld],
>>>> f_sz=%ld\n",
>>>> + err, start, (start + size), heap_file->fsz);
>>>> + WRITE_ONCE(*heap_fwork->failp, true);
>>>> + }
>>>> + // recovery to my cred.
>>>> + revert_creds(old_cred);
>>>> +}
>>>> +
>>>> +static int dma_heap_file_control_thread(void *data)
>>>> +{
>>>> + struct dma_heap_file_control *heap_fctl =
>>>> + (struct dma_heap_file_control *)data;
>>>> + struct dma_heap_file_work *worker, *tmp;
>>>> + int nr_work;
>>>> +
>>>> + LIST_HEAD(pages);
>>>> + LIST_HEAD(workers);
>>>> +
>>>> + while (true) {
>>>> + wait_event_freezable(heap_fctl->threadwq,
>>>> + atomic_read(&heap_fctl->nr_work) > 0);
>>>> +recheck:
>>>> + spin_lock(&heap_fctl->lock);
>>>> + list_splice_init(&heap_fctl->works, &workers);
>>>> + spin_unlock(&heap_fctl->lock);
>>>> +
>>>> + if (unlikely(kthread_should_stop())) {
>>>> + list_for_each_entry_safe(worker, tmp, &workers, list) {
>>>> + list_del(&worker->list);
>>>> + destroy_file_work(worker);
>>>> + }
>>>> + break;
>>>> + }
>>>> +
>>>> + nr_work = 0;
>>>> + list_for_each_entry_safe(worker, tmp, &workers, list) {
>>>> + ++nr_work;
>>>> + list_del(&worker->list);
>>>> + __work_this_io(worker);
>>>> +
>>>> + destroy_file_work(worker);
>>>> + }
>>>> + atomic_sub(nr_work, &heap_fctl->nr_work);
>>>> +
>>>> + if (atomic_read(&heap_fctl->nr_work) > 0)
>>>> + goto recheck;
>>>> + }
>>>> + return 0;
>>>> +}
>>>> +
>>>> +size_t dma_heap_file_size(struct dma_heap_file *heap_file)
>>>> +{
>>>> + return heap_file->fsz;
>>>> +}
>>>> +
>>>> +static int prepare_dma_heap_file(struct dma_heap_file *heap_file,
>>>> int file_fd,
>>>> + size_t batch)
>>>> +{
>>>> + struct file *file;
>>>> + size_t fsz;
>>>> + int ret;
>>>> +
>>>> + file = fget(file_fd);
>>>> + if (!file)
>>>> + return -EINVAL;
>>>> +
>>>> + fsz = i_size_read(file_inode(file));
>>>> + if (fsz < batch) {
>>>> + ret = -EINVAL;
>>>> + goto err;
>>>> + }
>>>> +
>>>> + /**
>>>> + * Selinux block our read, but actually we are reading the
>>>> stand-in
>>>> + * for this file.
>>>> + * So save current's cred and when going to read, override
>>>> mine, and
>>>> + * end of read, revert.
>>>> + */
>>>> + heap_file->cred = prepare_kernel_cred(current);
>>>> + if (unlikely(!heap_file->cred)) {
>>>> + ret = -ENOMEM;
>>>> + goto err;
>>>> + }
>>>> +
>>>> + heap_file->file = file;
>>>> + heap_file->max_batch = batch;
>>>> + heap_file->fsz = fsz;
>>>> +
>>>> + heap_file->direct = file->f_flags & O_DIRECT;
>>>> +
>>>> +#define DMA_HEAP_SUGGEST_DIRECT_IO_SIZE (1UL << 30)
>>>> + if (!heap_file->direct && fsz >= DMA_HEAP_SUGGEST_DIRECT_IO_SIZE)
>>>> + pr_warn("alloc read file better to use O_DIRECT to read
>>>> larget file\n");
>>>> +
>>>> + return 0;
>>>> +
>>>> +err:
>>>> + fput(file);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static void destroy_dma_heap_file(struct dma_heap_file *heap_file)
>>>> +{
>>>> + fput(heap_file->file);
>>>> + put_cred(heap_file->cred);
>>>> +}
>>>> +
>>>> +static int dma_heap_buffer_alloc_read_file(struct dma_heap *heap,
>>>> int file_fd,
>>>> + size_t batch, unsigned int fd_flags,
>>>> + unsigned int heap_flags)
>>>> +{
>>>> + struct dma_buf *dmabuf;
>>>> + int fd;
>>>> + struct dma_heap_file heap_file;
>>>> +
>>>> + fd = prepare_dma_heap_file(&heap_file, file_fd, batch);
>>>> + if (fd)
>>>> + goto error_file;
>>>> +
>>>> + dmabuf = heap->ops->allocate_read_file(heap, &heap_file,
>>>> fd_flags,
>>>> + heap_flags);
>>>> + if (IS_ERR(dmabuf)) {
>>>> + fd = PTR_ERR(dmabuf);
>>>> + goto error;
>>>> + }
>>>> +
>>>> + fd = dma_buf_fd(dmabuf, fd_flags);
>>>> + if (fd < 0) {
>>>> + dma_buf_put(dmabuf);
>>>> + /* just return, as put will call release and that will
>>>> free */
>>>> + }
>>>> +
>>>> +error:
>>>> + destroy_dma_heap_file(&heap_file);
>>>> +error_file:
>>>> + return fd;
>>>> +}
>>>> +
>>>> static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
>>>> u32 fd_flags,
>>>> u64 heap_flags)
>>>> @@ -93,6 +545,38 @@ static int dma_heap_open(struct inode *inode,
>>>> struct file *file)
>>>> return 0;
>>>> }
>>>> +static long dma_heap_ioctl_allocate_read_file(struct file *file,
>>>> void *data)
>>>> +{
>>>> + struct dma_heap_allocation_file_data *heap_allocation_file =
>>>> data;
>>>> + struct dma_heap *heap = file->private_data;
>>>> + int fd;
>>>> +
>>>> + if (heap_allocation_file->fd || !heap_allocation_file->file_fd)
>>>> + return -EINVAL;
>>>> +
>>>> + if (heap_allocation_file->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
>>>> + return -EINVAL;
>>>> +
>>>> + if (heap_allocation_file->heap_flags &
>>>> ~DMA_HEAP_VALID_HEAP_FLAGS)
>>>> + return -EINVAL;
>>>> +
>>>> + if (!heap->ops->allocate_read_file)
>>>> + return -EINVAL;
>>>> +
>>>> + fd = dma_heap_buffer_alloc_read_file(
>>>> + heap, heap_allocation_file->file_fd,
>>>> + heap_allocation_file->batch ?
>>>> + PAGE_ALIGN(heap_allocation_file->batch) :
>>>> + DEFAULT_ADI_BATCH,
>>>> + heap_allocation_file->fd_flags,
>>>> + heap_allocation_file->heap_flags);
>>>> + if (fd < 0)
>>>> + return fd;
>>>> +
>>>> + heap_allocation_file->fd = fd;
>>>> + return 0;
>>>> +}
>>>> +
>>>> static long dma_heap_ioctl_allocate(struct file *file, void *data)
>>>> {
>>>> struct dma_heap_allocation_data *heap_allocation = data;
>>>> @@ -121,6 +605,7 @@ static long dma_heap_ioctl_allocate(struct file
>>>> *file, void *data)
>>>> static unsigned int dma_heap_ioctl_cmds[] = {
>>>> DMA_HEAP_IOCTL_ALLOC,
>>>> + DMA_HEAP_IOCTL_ALLOC_AND_READ,
>>>> };
>>>> static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
>>>> @@ -170,6 +655,9 @@ static long dma_heap_ioctl(struct file *file,
>>>> unsigned int ucmd,
>>>> case DMA_HEAP_IOCTL_ALLOC:
>>>> ret = dma_heap_ioctl_allocate(file, kdata);
>>>> break;
>>>> + case DMA_HEAP_IOCTL_ALLOC_AND_READ:
>>>> + ret = dma_heap_ioctl_allocate_read_file(file, kdata);
>>>> + break;
>>>> default:
>>>> ret = -ENOTTY;
>>>> goto err;
>>>> @@ -316,11 +804,44 @@ static int dma_heap_init(void)
>>>> dma_heap_class = class_create(DEVNAME);
>>>> if (IS_ERR(dma_heap_class)) {
>>>> - unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
>>>> - return PTR_ERR(dma_heap_class);
>>>> + ret = PTR_ERR(dma_heap_class);
>>>> + goto fail_class;
>>>> }
>>>> dma_heap_class->devnode = dma_heap_devnode;
>>>> + heap_fctl = kzalloc(sizeof(*heap_fctl), GFP_KERNEL);
>>>> + if (unlikely(!heap_fctl)) {
>>>> + ret = -ENOMEM;
>>>> + goto fail_alloc;
>>>> + }
>>>> +
>>>> + INIT_LIST_HEAD(&heap_fctl->works);
>>>> + init_waitqueue_head(&heap_fctl->threadwq);
>>>> + init_waitqueue_head(&heap_fctl->workwq);
>>>> +
>>>> + heap_fctl->work_thread =
>>>> kthread_run(dma_heap_file_control_thread,
>>>> + heap_fctl, "heap_fwork_t");
>>>> + if (IS_ERR(heap_fctl->work_thread)) {
>>>> + ret = -ENOMEM;
>>>> + goto fail_thread;
>>>> + }
>>>> +
>>>> + heap_fctl->heap_fwork_cachep = KMEM_CACHE(dma_heap_file_work, 0);
>>>> + if (unlikely(!heap_fctl->heap_fwork_cachep)) {
>>>> + ret = -ENOMEM;
>>>> + goto fail_cache;
>>>> + }
>>>> +
>>>> return 0;
>>>> +
>>>> +fail_cache:
>>>> + kthread_stop(heap_fctl->work_thread);
>>>> +fail_thread:
>>>> + kfree(heap_fctl);
>>>> +fail_alloc:
>>>> + class_destroy(dma_heap_class);
>>>> +fail_class:
>>>> + unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
>>>> + return ret;
>>>> }
>>>> subsys_initcall(dma_heap_init);
>>>> diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
>>>> index 064bad725061..9c25383f816c 100644
>>>> --- a/include/linux/dma-heap.h
>>>> +++ b/include/linux/dma-heap.h
>>>> @@ -12,12 +12,17 @@
>>>> #include <linux/cdev.h>
>>>> #include <linux/types.h>
>>>> +#define DEFAULT_ADI_BATCH (128 << 20)
>>>> +
>>>> struct dma_heap;
>>>> +struct dma_heap_file_task;
>>>> +struct dma_heap_file;
>>>> /**
>>>> * struct dma_heap_ops - ops to operate on a given heap
>>>> * @allocate: allocate dmabuf and return struct dma_buf ptr
>>>> - *
>>>> + * @allocate_read_file: allocate dmabuf and read file, then return
>>>> struct
>>>> + * dma_buf ptr.
>>>> * allocate returns dmabuf on success, ERR_PTR(-errno) on error.
>>>> */
>>>> struct dma_heap_ops {
>>>> @@ -25,6 +30,11 @@ struct dma_heap_ops {
>>>> unsigned long len,
>>>> u32 fd_flags,
>>>> u64 heap_flags);
>>>> +
>>>> + struct dma_buf *(*allocate_read_file)(struct dma_heap *heap,
>>>> + struct dma_heap_file *heap_file,
>>>> + u32 fd_flags,
>>>> + u64 heap_flags);
>>>> };
>>>> /**
>>>> @@ -65,4 +75,49 @@ const char *dma_heap_get_name(struct dma_heap
>>>> *heap);
>>>> */
>>>> struct dma_heap *dma_heap_add(const struct dma_heap_export_info
>>>> *exp_info);
>>>> +/**
>>>> + * dma_heap_destroy_file_read - waits for a file read to complete
>>>> then destroy it
>>>> + * Returns: true if the file read failed, false otherwise
>>>> + */
>>>> +bool dma_heap_destroy_file_read(struct dma_heap_file_task
>>>> *heap_ftask);
>>>> +
>>>> +/**
>>>> + * dma_heap_wait_for_file_read - waits for a file read to complete
>>>> + * Returns: true if the file read failed, false otherwise
>>>> + */
>>>> +bool dma_heap_wait_for_file_read(struct dma_heap_file_task
>>>> *heap_ftask);
>>>> +
>>>> +/**
>>>> + * dma_heap_alloc_file_read - Declare a task to read file when
>>>> allocate pages.
>>>> + * @heap_file: target file to read
>>>> + *
>>>> + * Return NULL if failed, otherwise return a struct pointer.
>>>> + */
>>>> +struct dma_heap_file_task *
>>>> +dma_heap_declare_file_read(struct dma_heap_file *heap_file);
>>>> +
>>>> +/**
>>>> + * dma_heap_prepare_file_read - cache each allocated page until we
>>>> meet this batch.
>>>> + * @heap_ftask: prepared and need to commit's work.
>>>> + * @page: current allocated page. don't care which order.
>>>> + *
>>>> + * Returns true if reach to batch, false so go on prepare.
>>>> + */
>>>> +bool dma_heap_prepare_file_read(struct dma_heap_file_task
>>>> *heap_ftask,
>>>> + struct page *page);
>>>> +
>>>> +/**
>>>> + * dma_heap_commit_file_read - prepare collect enough memory,
>>>> going to trigger IO
>>>> + * @heap_ftask: info that current IO needs
>>>> + *
>>>> + * This commit will also check if reach to tail read.
>>>> + * For direct I/O submissions, it is necessary to pay attention to
>>>> file reads
>>>> + * that are not page-aligned. For the unaligned portion of the
>>>> read, buffer IO
>>>> + * needs to be triggered.
>>>> + * Returns:
>>>> + * 0 if all right, -errno if something wrong
>>>> + */
>>>> +int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask);
>>>> +size_t dma_heap_file_size(struct dma_heap_file *heap_file);
>>>> +
>>>> #endif /* _DMA_HEAPS_H */
>>>> diff --git a/include/uapi/linux/dma-heap.h
>>>> b/include/uapi/linux/dma-heap.h
>>>> index a4cf716a49fa..8c20e8b74eed 100644
>>>> --- a/include/uapi/linux/dma-heap.h
>>>> +++ b/include/uapi/linux/dma-heap.h
>>>> @@ -39,6 +39,27 @@ struct dma_heap_allocation_data {
>>>> __u64 heap_flags;
>>>> };
>>>> +/**
>>>> + * struct dma_heap_allocation_file_data - metadata passed from
>>>> userspace for
>>>> + * allocations and read file
>>>> + * @fd: will be populated with a fd which provides the
>>>> + * handle to the allocated dma-buf
>>>> + * @file_fd: file descriptor to read from(suggested to use
>>>> O_DIRECT open file)
>>>> + * @batch: how many memory alloced then file read(bytes),
>>>> default 128MB
>>>> + * will auto aligned to PAGE_SIZE
>>>> + * @fd_flags: file descriptor flags used when allocating
>>>> + * @heap_flags: flags passed to heap
>>>> + *
>>>> + * Provided by userspace as an argument to the ioctl
>>>> + */
>>>> +struct dma_heap_allocation_file_data {
>>>> + __u32 fd;
>>>> + __u32 file_fd;
>>>> + __u32 batch;
>>>> + __u32 fd_flags;
>>>> + __u64 heap_flags;
>>>> +};
>>>> +
>>>> #define DMA_HEAP_IOC_MAGIC 'H'
>>>> /**
>>>> @@ -50,4 +71,15 @@ struct dma_heap_allocation_data {
>>>> #define DMA_HEAP_IOCTL_ALLOC _IOWR(DMA_HEAP_IOC_MAGIC, 0x0,\
>>>> struct dma_heap_allocation_data)
>>>> +/**
>>>> + * DOC: DMA_HEAP_IOCTL_ALLOC_AND_READ - allocate memory from pool
>>>> and both
>>>> + * read file when allocate memory.
>>>> + *
>>>> + * Takes a dma_heap_allocation_file_data struct and returns it
>>>> with the fd field
>>>> + * populated with the dmabuf handle of the allocation. When
>>>> return, the dma-buf
>>>> + * content is read from file.
>>>> + */
>>>> +#define DMA_HEAP_IOCTL_ALLOC_AND_READ \
>>>> + _IOWR(DMA_HEAP_IOC_MAGIC, 0x1, struct
>>>> dma_heap_allocation_file_data)
>>>> +
>>>> #endif /* _UAPI_LINUX_DMABUF_POOL_H */
>>>
>
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