Re: [PATCH v1 2/7] v4l: videobuf2: add generic memory handling routines

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em 09-09-2010 06:19, Pawel Osciak escreveu:
> Add generic memory handling routines for userspace pointer handling,
> contiguous memory verification and mapping.
> 
> Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/media/video/Kconfig            |    3 +
>  drivers/media/video/Makefile           |    2 +
>  drivers/media/video/videobuf2-memops.c |  181 ++++++++++++++++++++++++++++++++
>  include/media/videobuf2-memops.h       |   27 +++++
>  4 files changed, 213 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/media/video/videobuf2-memops.c
>  create mode 100644 include/media/videobuf2-memops.h
> 
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index 5764443..e4ac3e2 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -51,6 +51,9 @@ config V4L2_MEM2MEM_DEV
>  config VIDEOBUF2_CORE
>  	tristate
>  
> +config VIDEOBUF2_MEMOPS
> +	tristate
> +
>  
>  #
>  # Multimedia Video device configuration
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index e66f53b..ab5b521 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -118,6 +118,8 @@ obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
>  obj-$(CONFIG_VIDEO_BTCX)  += btcx-risc.o
>  
>  obj-$(CONFIG_VIDEOBUF2_CORE)		+= videobuf2-core.o
> +obj-$(CONFIG_VIDEOBUF2_MEMOPS)		+= videobuf2-memops.o
> +
>  
>  obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
>  
> diff --git a/drivers/media/video/videobuf2-memops.c b/drivers/media/video/videobuf2-memops.c
> new file mode 100644
> index 0000000..fa76983
> --- /dev/null
> +++ b/drivers/media/video/videobuf2-memops.c
> @@ -0,0 +1,181 @@
> +/*
> + * videobuf2-memops.c - generic memory handling routines for videobuf2
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <p.osciak@samsung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.

Hmm... it should be saying GPL version 2 (or v2+). Please fix on all files 
for your next set of RFC patches.

> + */
> +
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/vmalloc.h>
> +#include <linux/cma.h>
> +#include <linux/mm.h>
> +#include <linux/sched.h>
> +#include <linux/file.h>
> +
> +#include <media/videobuf2-core.h>
> +
> +/**
> + * vb2_contig_verify_userptr() - verify contiguity of a userspace-mapped memory
> + * @vma:	virtual memory region which maps the physical memory
> + *		to be verified
> + * @vaddr:	starting virtual address of the area to be verified
> + * @size:	size of the area to be verified
> + * @paddr:	will return physical address for the given vaddr
> + *
> + * This function will go through memory area of size size mapped at vaddr and
> + * verify that the underlying physical pages are contiguous.
> + *
> + * Returns 0 on success and a physical address to the memory pointed
> + * to by vaddr in paddr.
> + */
> +int vb2_contig_verify_userptr(struct vm_area_struct *vma,
> +				unsigned long vaddr, unsigned long size,
> +				unsigned long *paddr)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned long offset;
> +	unsigned long vma_size;
> +	unsigned long curr_pfn, prev_pfn;
> +	unsigned long num_pages;
> +	int ret = -EINVAL;
> +	unsigned int i;
> +
> +	offset = vaddr & ~PAGE_MASK;
> +
> +	down_read(&mm->mmap_sem);
> +
> +	vma = find_vma(mm, vaddr);
> +	if (!vma) {
> +		printk(KERN_ERR "Invalid userspace address\n");
> +		goto done;
> +	}
> +
> +	vma_size = vma->vm_end - vma->vm_start;
> +
> +	if (size > vma_size - offset) {
> +		printk(KERN_ERR "Region too small\n");
> +		goto done;
> +	}
> +	num_pages = (size + offset) >> PAGE_SHIFT;
> +
> +	ret = follow_pfn(vma, vaddr, &curr_pfn);
> +	if (ret) {
> +		printk(KERN_ERR "Invalid userspace address\n");
> +		goto done;
> +	}
> +
> +	*paddr = (curr_pfn << PAGE_SHIFT) + offset;
> +
> +	for (i = 1; i < num_pages; ++i) {
> +		prev_pfn = curr_pfn;
> +		vaddr += PAGE_SIZE;
> +
> +		ret = follow_pfn(vma, vaddr, &curr_pfn);
> +		if (ret || curr_pfn != prev_pfn + 1) {
> +			printk(KERN_ERR "Invalid userspace address\n");
> +			ret = -EINVAL;
> +			break;
> +		}
> +	}
> +
> +done:
> +	up_read(&mm->mmap_sem);
> +	return ret;
> +}
> +
> +/**
> + * vb2_mmap_pfn_range() - map physical pages to userspace
> + * @vma:	virtual memory region for the mapping
> + * @paddr:	starting physical address of the memory to be mapped
> + * @size:	size of the memory to be mapped
> + * @vm_ops:	vm operations to be assigned to the created area
> + * @priv:	private data to be associated with the area
> + *
> + * Returns 0 on success.
> + */
> +int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
> +				unsigned long size,
> +				const struct vm_operations_struct *vm_ops,
> +				void *priv)
> +{
> +	int ret;
> +
> +	size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
> +
> +	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> +	ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
> +				size, vma->vm_page_prot);
> +	if (ret) {
> +		printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
> +		return ret;
> +	}
> +
> +	vma->vm_flags		|= VM_DONTEXPAND | VM_RESERVED;
> +	vma->vm_private_data	= priv;
> +	vma->vm_ops		= vm_ops;
> +
> +	vm_ops->open(vma);
> +
> +	printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
> +			__func__, paddr, vma->vm_start, size);
> +
> +	return 0;
> +}
> +
> +/**
> + * vb2_get_userptr() - acquire an area pointed to by userspace addres vaddr
> + * @vaddr:	virtual userspace address to the given area
> + *
> + * This function attempts to acquire an area mapped in the userspace for
> + * the duration of a hardware operation.
> + *
> + * Returns a virtual memory region associated with the given vaddr on success
> + * or NULL.
> + */
> +struct vm_area_struct *vb2_get_userptr(unsigned long vaddr)
> +{
> +	struct mm_struct *mm = current->mm;
> +	struct vm_area_struct *vma;
> +
> +	down_read(&mm->mmap_sem);
> +
> +	vma = find_vma(mm, vaddr);
> +	if (!vma)
> +		goto done;
> +
> +	if (vma->vm_ops && vma->vm_ops->open)
> +		vma->vm_ops->open(vma);
> +
> +	if (vma->vm_file)
> +		get_file(vma->vm_file);
> +
> +done:
> +	up_read(&mm->mmap_sem);
> +	return vma;
> +}
> +
> +/**
> + * vb2_put_userptr() - release a userspace memory area
> + * @vma:	virtual memory region associated with the area to be released
> + *
> + * This function releases the previously acquired memory area after a hardware
> + * operation.
> + */
> +void vb2_put_userptr(struct vm_area_struct *vma)
> +{
> +	if (!vma)
> +		return;
> +
> +	if (vma->vm_file)
> +		fput(vma->vm_file);
> +
> +	if (vma->vm_ops && vma->vm_ops->close)
> +		vma->vm_ops->close(vma);
> +}
> diff --git a/include/media/videobuf2-memops.h b/include/media/videobuf2-memops.h
> new file mode 100644
> index 0000000..23db249
> --- /dev/null
> +++ b/include/media/videobuf2-memops.h
> @@ -0,0 +1,27 @@
> +/*
> + * videobuf2-memops.h - generic memory handling routines for videobuf2
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <p.osciak@samsung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <media/videobuf2-core.h>
> +
> +int vb2_contig_verify_userptr(struct vm_area_struct *vma,
> +				unsigned long vaddr, unsigned long size,
> +				unsigned long *paddr);
> +
> +int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
> +				unsigned long size,
> +				const struct vm_operations_struct *vm_ops,
> +				void *priv);
> +
> +struct vm_area_struct *vb2_get_userptr(unsigned long vaddr);
> +
> +void vb2_put_userptr(struct vm_area_struct *vma);
> +