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[module] improve dmabuf mmap logic for vmalloc'd memory

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Instead of faulting the pages in one by one when mmaping on the dma fd,
we could instead use remap_vmalloc_range to map in all the memory at
once.
This commit is contained in:
Quantum 2021-02-05 22:54:47 -05:00 committed by Geoffrey McRae
parent f65aa6e089
commit 2c909f0af7
1 changed files with 24 additions and 3 deletions
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27
module/kvmfr.c
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@ -75,6 +75,7 @@ struct kvmfrbuf
{
struct kvmfr_dev * kdev;
pgoff_t pagecount;
unsigned long offset;
struct page ** pages;
};
@ -139,11 +140,29 @@ static void release_kvmfrbuf(struct dma_buf * buf)
static int mmap_kvmfrbuf(struct dma_buf * buf, struct vm_area_struct * vma)
{
struct kvmfrbuf * kbuf = (struct kvmfrbuf *)buf->priv;
unsigned long size = vma->vm_end - vma->vm_start;
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
if ((offset + size > (kbuf->pagecount << PAGE_SHIFT)) || (offset + size < offset))
return -EINVAL;
if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
return -EINVAL;
vma->vm_ops = &kvmfr_vm_ops;
vma->vm_private_data = buf->priv;
return 0;
switch (kbuf->kdev->type)
{
case KVMFR_TYPE_PCI:
vma->vm_ops = &kvmfr_vm_ops;
vma->vm_private_data = buf->priv;
return 0;
case KVMFR_TYPE_STATIC:
return remap_vmalloc_range(vma, kbuf->kdev->addr + kbuf->offset, vma->vm_pgoff);
default:
return -EINVAL;
}
}
static const struct dma_buf_ops kvmfrbuf_ops =
@ -184,6 +203,7 @@ static long kvmfr_dmabuf_create(struct kvmfr_dev * kdev, struct file * filp, uns
kbuf->kdev = kdev;
kbuf->pagecount = create.size >> PAGE_SHIFT;
kbuf->offset = create.offset;
kbuf->pages = kmalloc_array(kbuf->pagecount, sizeof(*kbuf->pages), GFP_KERNEL);
if (!kbuf->pages)
{
@ -279,6 +299,7 @@ static int device_mmap(struct file * filp, struct vm_area_struct * vma)
{
case KVMFR_TYPE_STATIC:
return remap_vmalloc_range(vma, kdev->addr, vma->vm_pgoff);
default:
return -ENODEV;
}