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Message-ID: <80426e64-d334-4e61-8870-a3da08705f9d@vivo.com>
Date: Fri, 12 Jul 2024 15:29:31 +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 2024/7/12 15:10, Christian König 写道:
> Am 12.07.24 um 04:14 schrieb Huan Yang:
>> 在 2024/7/12 9:59, Huan Yang 写道:
>>> 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.
>
> And exactly that is a no-go. Use the existing IOCTLs and system calls
> instead they should have similar performance when done right.
Get it, but In my testing process, even without memory pressure, it
takes about 60ms to allocate a 3GB DMA-BUF. When there is significant
memory pressure, the allocation time for a 3GB
DMA-BUF can increase to 300ms-1s. (The above test times can also
demonstrate the difference.)
But, talk is cheap, I agree to research use existing way to implements
it and give a test.
I'll show this if I done .
Thanks for your suggestions.
>
> Regards,
> Christian.
>
>>
>> You can see cover-letter, here are the normal test and this IOCTL's
>> compare in memory pressure, even if buffered I/O in this ioctl can
>> have 50% improve by parallel.
>>
>> dd a 3GB file for test, 12G RAM phone, UFS4.0, stressapptest 4G
>> memory pressure.
>>
>> 1. original
>> ```shel
>> # create a model file
>> dd if=/dev/zero of=./model.txt bs=1M count=3072
>> # drop page cache
>> echo 3 > /proc/sys/vm/drop_caches
>> ./dmabuf-heap-file-read mtk_mm-uncached normal
>>
>>> result is total cost 13087213847ns
>>
>> ```
>>
>> 2.DMA_HEAP_IOCTL_ALLOC_AND_READ O_DIRECT
>> ```shel
>> # create a model file
>> dd if=/dev/zero of=./model.txt bs=1M count=3072
>> # drop page cache
>> echo 3 > /proc/sys/vm/drop_caches
>> ./dmabuf-heap-file-read mtk_mm-uncached direct_io
>>
>>> result is total cost 2902386846ns
>>
>> # use direct_io_check can check the content if is same to file.
>> ```
>>
>> 3. DMA_HEAP_IOCTL_ALLOC_AND_READ BUFFER I/O
>> ```shel
>> # create a model file
>> dd if=/dev/zero of=./model.txt bs=1M count=3072
>> # drop page cache
>> echo 3 > /proc/sys/vm/drop_caches
>> ./dmabuf-heap-file-read mtk_mm-uncached normal_io
>>
>>> result is total cost 5735579385ns
>>
>> ```
>>
>>>
>>> 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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