Re: [PATCHv3 07/22] staging: android: ion: Remove page faulting support

Archit Taneja
2017-04-11T06:00:33Z

Hi,

On 04/04/2017 12:27 AM, Laura Abbott wrote:
> The new method of syncing with dma_map means that the page faulting sync
> implementation is no longer applicable. Remove it.
>
> Signed-off-by: Laura Abbott <labbott@redhat.com>
> ---
> drivers/staging/android/ion/ion.c | 117 --------------------------------------
> 1 file changed, 117 deletions(-)
>
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index 6aac935..226ea1f 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -42,37 +42,11 @@
> #include "ion_priv.h"
> #include "compat_ion.h"
>
> -bool ion_buffer_fault_user_mappings(struct ion_buffer *buffer)
> -{
> - return (buffer->flags & ION_FLAG_CACHED) &&
> - !(buffer->flags & ION_FLAG_CACHED_NEEDS_SYNC);
> -}
> -
> bool ion_buffer_cached(struct ion_buffer *buffer)
> {
> return !!(buffer->flags & ION_FLAG_CACHED);
> }
>
> -static inline struct page *ion_buffer_page(struct page *page)
> -{
> - return (struct page *)((unsigned long)page & ~(1UL));
> -}
> -
> -static inline bool ion_buffer_page_is_dirty(struct page *page)
> -{
> - return !!((unsigned long)page & 1UL);
> -}
> -
> -static inline void ion_buffer_page_dirty(struct page **page)
> -{
> - *page = (struct page *)((unsigned long)(*page) | 1UL);
> -}
> -
> -static inline void ion_buffer_page_clean(struct page **page)
> -{
> - *page = (struct page *)((unsigned long)(*page) & ~(1UL));
> -}
> -
> /* this function should only be called while dev->lock is held */
> static void ion_buffer_add(struct ion_device *dev,
> struct ion_buffer *buffer)
> @@ -140,25 +114,6 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
> buffer->dev = dev;
> buffer->size = len;
>
> - if (ion_buffer_fault_user_mappings(buffer)) {
> - int num_pages = PAGE_ALIGN(buffer->size) / PAGE_SIZE;
> - struct scatterlist *sg;
> - int i, j, k = 0;
> -
> - buffer->pages = vmalloc(sizeof(struct page *) * num_pages);

We should also remove the vfree(buffer->pages) call in ion_buffer_destroy. In fact, we
could removes 'pages' member from ion_buffer altogether.

Thanks,
Archit

> - if (!buffer->pages) {
> - ret = -ENOMEM;
> - goto err1;
> - }
> -
> - for_each_sg(table->sgl, sg, table->nents, i) {
> - struct page *page = sg_page(sg);
> -
> - for (j = 0; j < sg->length / PAGE_SIZE; j++)
> - buffer->pages[k++] = page++;
> - }
> - }
> -
> buffer->dev = dev;
> buffer->size = len;
> INIT_LIST_HEAD(&buffer->vmas);
> @@ -924,69 +879,6 @@ void ion_pages_sync_for_device(struct device *dev, struct page *page,
> dma_sync_sg_for_device(dev, &sg, 1, dir);
> }
>
> -struct ion_vma_list {
> - struct list_head list;
> - struct vm_area_struct *vma;
> -};
> -
> -static int ion_vm_fault(struct vm_fault *vmf)
> -{
> - struct ion_buffer *buffer = vmf->vma->vm_private_data;
> - unsigned long pfn;
> - int ret;
> -
> - mutex_lock(&buffer->lock);
> - ion_buffer_page_dirty(buffer->pages + vmf->pgoff);
> - BUG_ON(!buffer->pages || !buffer->pages[vmf->pgoff]);
> -
> - pfn = page_to_pfn(ion_buffer_page(buffer->pages[vmf->pgoff]));
> - ret = vm_insert_pfn(vmf->vma, vmf->address, pfn);
> - mutex_unlock(&buffer->lock);
> - if (ret)
> - return VM_FAULT_ERROR;
> -
> - return VM_FAULT_NOPAGE;
> -}
> -
> -static void ion_vm_open(struct vm_area_struct *vma)
> -{
> - struct ion_buffer *buffer = vma->vm_private_data;
> - struct ion_vma_list *vma_list;
> -
> - vma_list = kmalloc(sizeof(*vma_list), GFP_KERNEL);
> - if (!vma_list)
> - return;
> - vma_list->vma = vma;
> - mutex_lock(&buffer->lock);
> - list_add(&vma_list->list, &buffer->vmas);
> - mutex_unlock(&buffer->lock);
> - pr_debug("%s: adding %p\n", __func__, vma);
> -}
> -
> -static void ion_vm_close(struct vm_area_struct *vma)
> -{
> - struct ion_buffer *buffer = vma->vm_private_data;
> - struct ion_vma_list *vma_list, *tmp;
> -
> - pr_debug("%s\n", __func__);
> - mutex_lock(&buffer->lock);
> - list_for_each_entry_safe(vma_list, tmp, &buffer->vmas, list) {
> - if (vma_list->vma != vma)
> - continue;
> - list_del(&vma_list->list);
> - kfree(vma_list);
> - pr_debug("%s: deleting %p\n", __func__, vma);
> - break;
> - }
> - mutex_unlock(&buffer->lock);
> -}
> -
> -static const struct vm_operations_struct ion_vma_ops = {
> - .open = ion_vm_open,
> - .close = ion_vm_close,
> - .fault = ion_vm_fault,
> -};
> -
> static int ion_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
> {
> struct ion_buffer *buffer = dmabuf->priv;
> @@ -998,15 +890,6 @@ static int ion_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
> return -EINVAL;
> }
>
> - if (ion_buffer_fault_user_mappings(buffer)) {
> - vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND |
> - VM_DONTDUMP;
> - vma->vm_private_data = buffer;
> - vma->vm_ops = &ion_vma_ops;
> - ion_vm_open(vma);
> - return 0;
> - }
> -
> if (!(buffer->flags & ION_FLAG_CACHED))
> vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
>
>

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