[PATCH 9/9] [media] mm: Move get_vaddr_frames() behind a config option
Josh Triplett
josh at joshtriplett.org
Wed Jun 10 09:37:20 PDT 2015
On Wed, Jun 10, 2015 at 06:20:52AM -0300, Mauro Carvalho Chehab wrote:
> From: Jan Kara <jack at suse.cz>
>
> get_vaddr_frames() is used by relatively rare drivers so hide it and the
> related functions behind a config option that is selected only by
> drivers that need the infrastructure.
>
> Suggested-by: Andrew Morton <akpm at linux-foundation.org>
>
> Signed-off-by: Jan Kara <jack at suse.cz>
> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab at osg.samsung.com>
Seems sensible to me.
Since this patch makes the kernel smaller, can you include the delta
from bloat-o-meter between allnoconfig with and without this patch?
Also, I assume you've compile-tested the kernel with allyesconfig minus
the three options that now have "select FRAME_VECTOR", to make sure it
builds?
> create mode 100644 mm/frame_vector.c
>
> diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
> index 0a6780367d28..fc678289cf79 100644
> --- a/drivers/gpu/drm/exynos/Kconfig
> +++ b/drivers/gpu/drm/exynos/Kconfig
> @@ -71,6 +71,7 @@ config DRM_EXYNOS_VIDI
> config DRM_EXYNOS_G2D
> bool "Exynos DRM G2D"
> depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_G2D
> + select FRAME_VECTOR
> help
> Choose this option if you want to use Exynos G2D for DRM.
>
> diff --git a/drivers/media/platform/omap/Kconfig b/drivers/media/platform/omap/Kconfig
> index dc2aaab54aef..217d613b0fe7 100644
> --- a/drivers/media/platform/omap/Kconfig
> +++ b/drivers/media/platform/omap/Kconfig
> @@ -10,6 +10,7 @@ config VIDEO_OMAP2_VOUT
> select OMAP2_DSS if HAS_IOMEM && ARCH_OMAP2PLUS
> select OMAP2_VRFB if ARCH_OMAP2 || ARCH_OMAP3
> select VIDEO_OMAP2_VOUT_VRFB if VIDEO_OMAP2_VOUT && OMAP2_VRFB
> + select FRAME_VECTOR
> default n
> ---help---
> V4L2 Display driver support for OMAP2/3 based boards.
> diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
> index f7a01a72eb9e..f38f6e387f04 100644
> --- a/drivers/media/v4l2-core/Kconfig
> +++ b/drivers/media/v4l2-core/Kconfig
> @@ -73,6 +73,7 @@ config VIDEOBUF2_CORE
>
> config VIDEOBUF2_MEMOPS
> tristate
> + select FRAME_VECTOR
>
> config VIDEOBUF2_DMA_CONTIG
> tristate
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 390214da4546..2ca52e9986f0 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -635,3 +635,6 @@ config MAX_STACK_SIZE_MB
> changed to a smaller value in which case that is used.
>
> A sane initial value is 80 MB.
> +
> +config FRAME_VECTOR
> + bool
> diff --git a/mm/Makefile b/mm/Makefile
> index 98c4eaeabdcb..be5d5c866305 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -78,3 +78,4 @@ obj-$(CONFIG_CMA) += cma.o
> obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
> obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
> obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
> +obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
> diff --git a/mm/frame_vector.c b/mm/frame_vector.c
> new file mode 100644
> index 000000000000..31a2bd5f41d5
> --- /dev/null
> +++ b/mm/frame_vector.c
> @@ -0,0 +1,232 @@
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/mm.h>
> +#include <linux/slab.h>
> +#include <linux/pagemap.h>
> +#include <linux/sched.h>
> +
> +/*
> + * get_vaddr_frames() - map virtual addresses to pfns
> + * @start: starting user address
> + * @nr_frames: number of pages / pfns from start to map
> + * @write: whether pages will be written to by the caller
> + * @force: whether to force write access even if user mapping is
> + * readonly. See description of the same argument of
> + get_user_pages().
> + * @vec: structure which receives pages / pfns of the addresses mapped.
> + * It should have space for at least nr_frames entries.
> + *
> + * This function maps virtual addresses from @start and fills @vec structure
> + * with page frame numbers or page pointers to corresponding pages (choice
> + * depends on the type of the vma underlying the virtual address). If @start
> + * belongs to a normal vma, the function grabs reference to each of the pages
> + * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
> + * touch page structures and the caller must make sure pfns aren't reused for
> + * anything else while he is using them.
> + *
> + * The function returns number of pages mapped which may be less than
> + * @nr_frames. In particular we stop mapping if there are more vmas of
> + * different type underlying the specified range of virtual addresses.
> + * When the function isn't able to map a single page, it returns error.
> + *
> + * This function takes care of grabbing mmap_sem as necessary.
> + */
> +int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
> + bool write, bool force, struct frame_vector *vec)
> +{
> + struct mm_struct *mm = current->mm;
> + struct vm_area_struct *vma;
> + int ret = 0;
> + int err;
> + int locked;
> +
> + if (nr_frames == 0)
> + return 0;
> +
> + if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
> + nr_frames = vec->nr_allocated;
> +
> + down_read(&mm->mmap_sem);
> + locked = 1;
> + vma = find_vma_intersection(mm, start, start + 1);
> + if (!vma) {
> + ret = -EFAULT;
> + goto out;
> + }
> + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
> + vec->got_ref = true;
> + vec->is_pfns = false;
> + ret = get_user_pages_locked(current, mm, start, nr_frames,
> + write, force, (struct page **)(vec->ptrs), &locked);
> + goto out;
> + }
> +
> + vec->got_ref = false;
> + vec->is_pfns = true;
> + do {
> + unsigned long *nums = frame_vector_pfns(vec);
> +
> + while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
> + err = follow_pfn(vma, start, &nums[ret]);
> + if (err) {
> + if (ret == 0)
> + ret = err;
> + goto out;
> + }
> + start += PAGE_SIZE;
> + ret++;
> + }
> + /*
> + * We stop if we have enough pages or if VMA doesn't completely
> + * cover the tail page.
> + */
> + if (ret >= nr_frames || start < vma->vm_end)
> + break;
> + vma = find_vma_intersection(mm, start, start + 1);
> + } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
> +out:
> + if (locked)
> + up_read(&mm->mmap_sem);
> + if (!ret)
> + ret = -EFAULT;
> + if (ret > 0)
> + vec->nr_frames = ret;
> + return ret;
> +}
> +EXPORT_SYMBOL(get_vaddr_frames);
> +
> +/**
> + * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
> + * them
> + * @vec: frame vector to put
> + *
> + * Drop references to pages if get_vaddr_frames() acquired them. We also
> + * invalidate the frame vector so that it is prepared for the next call into
> + * get_vaddr_frames().
> + */
> +void put_vaddr_frames(struct frame_vector *vec)
> +{
> + int i;
> + struct page **pages;
> +
> + if (!vec->got_ref)
> + goto out;
> + pages = frame_vector_pages(vec);
> + /*
> + * frame_vector_pages() might needed to do a conversion when
> + * get_vaddr_frames() got pages but vec was later converted to pfns.
> + * But it shouldn't really fail to convert pfns back...
> + */
> + if (WARN_ON(IS_ERR(pages)))
> + goto out;
> + for (i = 0; i < vec->nr_frames; i++)
> + put_page(pages[i]);
> + vec->got_ref = false;
> +out:
> + vec->nr_frames = 0;
> +}
> +EXPORT_SYMBOL(put_vaddr_frames);
> +
> +/**
> + * frame_vector_to_pages - convert frame vector to contain page pointers
> + * @vec: frame vector to convert
> + *
> + * Convert @vec to contain array of page pointers. If the conversion is
> + * successful, return 0. Otherwise return an error. Note that we do not grab
> + * page references for the page structures.
> + */
> +int frame_vector_to_pages(struct frame_vector *vec)
> +{
> + int i;
> + unsigned long *nums;
> + struct page **pages;
> +
> + if (!vec->is_pfns)
> + return 0;
> + nums = frame_vector_pfns(vec);
> + for (i = 0; i < vec->nr_frames; i++)
> + if (!pfn_valid(nums[i]))
> + return -EINVAL;
> + pages = (struct page **)nums;
> + for (i = 0; i < vec->nr_frames; i++)
> + pages[i] = pfn_to_page(nums[i]);
> + vec->is_pfns = false;
> + return 0;
> +}
> +EXPORT_SYMBOL(frame_vector_to_pages);
> +
> +/**
> + * frame_vector_to_pfns - convert frame vector to contain pfns
> + * @vec: frame vector to convert
> + *
> + * Convert @vec to contain array of pfns.
> + */
> +void frame_vector_to_pfns(struct frame_vector *vec)
> +{
> + int i;
> + unsigned long *nums;
> + struct page **pages;
> +
> + if (vec->is_pfns)
> + return;
> + pages = (struct page **)(vec->ptrs);
> + nums = (unsigned long *)pages;
> + for (i = 0; i < vec->nr_frames; i++)
> + nums[i] = page_to_pfn(pages[i]);
> + vec->is_pfns = true;
> +}
> +EXPORT_SYMBOL(frame_vector_to_pfns);
> +
> +/**
> + * frame_vector_create() - allocate & initialize structure for pinned pfns
> + * @nr_frames: number of pfns slots we should reserve
> + *
> + * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
> + * pfns.
> + */
> +struct frame_vector *frame_vector_create(unsigned int nr_frames)
> +{
> + struct frame_vector *vec;
> + int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
> +
> + if (WARN_ON_ONCE(nr_frames == 0))
> + return NULL;
> + /*
> + * This is absurdly high. It's here just to avoid strange effects when
> + * arithmetics overflows.
> + */
> + if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
> + return NULL;
> + /*
> + * Avoid higher order allocations, use vmalloc instead. It should
> + * be rare anyway.
> + */
> + if (size <= PAGE_SIZE)
> + vec = kmalloc(size, GFP_KERNEL);
> + else
> + vec = vmalloc(size);
> + if (!vec)
> + return NULL;
> + vec->nr_allocated = nr_frames;
> + vec->nr_frames = 0;
> + return vec;
> +}
> +EXPORT_SYMBOL(frame_vector_create);
> +
> +/**
> + * frame_vector_destroy() - free memory allocated to carry frame vector
> + * @vec: Frame vector to free
> + *
> + * Free structure allocated by frame_vector_create() to carry frames.
> + */
> +void frame_vector_destroy(struct frame_vector *vec)
> +{
> + /* Make sure put_vaddr_frames() got called properly... */
> + VM_BUG_ON(vec->nr_frames > 0);
> + if (!is_vmalloc_addr(vec))
> + kfree(vec);
> + else
> + vfree(vec);
> +}
> +EXPORT_SYMBOL(frame_vector_destroy);
> diff --git a/mm/gup.c b/mm/gup.c
> index 9d7f4fde30cb..222d57e335f9 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -937,231 +937,6 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> return ret; /* 0 or negative error code */
> }
>
> -/*
> - * get_vaddr_frames() - map virtual addresses to pfns
> - * @start: starting user address
> - * @nr_frames: number of pages / pfns from start to map
> - * @write: whether pages will be written to by the caller
> - * @force: whether to force write access even if user mapping is
> - * readonly. See description of the same argument of
> - get_user_pages().
> - * @vec: structure which receives pages / pfns of the addresses mapped.
> - * It should have space for at least nr_frames entries.
> - *
> - * This function maps virtual addresses from @start and fills @vec structure
> - * with page frame numbers or page pointers to corresponding pages (choice
> - * depends on the type of the vma underlying the virtual address). If @start
> - * belongs to a normal vma, the function grabs reference to each of the pages
> - * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
> - * touch page structures and the caller must make sure pfns aren't reused for
> - * anything else while he is using them.
> - *
> - * The function returns number of pages mapped which may be less than
> - * @nr_frames. In particular we stop mapping if there are more vmas of
> - * different type underlying the specified range of virtual addresses.
> - * When the function isn't able to map a single page, it returns error.
> - *
> - * This function takes care of grabbing mmap_sem as necessary.
> - */
> -int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
> - bool write, bool force, struct frame_vector *vec)
> -{
> - struct mm_struct *mm = current->mm;
> - struct vm_area_struct *vma;
> - int ret = 0;
> - int err;
> - int locked;
> -
> - if (nr_frames == 0)
> - return 0;
> -
> - if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
> - nr_frames = vec->nr_allocated;
> -
> - down_read(&mm->mmap_sem);
> - locked = 1;
> - vma = find_vma_intersection(mm, start, start + 1);
> - if (!vma) {
> - ret = -EFAULT;
> - goto out;
> - }
> - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
> - vec->got_ref = true;
> - vec->is_pfns = false;
> - ret = get_user_pages_locked(current, mm, start, nr_frames,
> - write, force, (struct page **)(vec->ptrs), &locked);
> - goto out;
> - }
> -
> - vec->got_ref = false;
> - vec->is_pfns = true;
> - do {
> - unsigned long *nums = frame_vector_pfns(vec);
> -
> - while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
> - err = follow_pfn(vma, start, &nums[ret]);
> - if (err) {
> - if (ret == 0)
> - ret = err;
> - goto out;
> - }
> - start += PAGE_SIZE;
> - ret++;
> - }
> - /*
> - * We stop if we have enough pages or if VMA doesn't completely
> - * cover the tail page.
> - */
> - if (ret >= nr_frames || start < vma->vm_end)
> - break;
> - vma = find_vma_intersection(mm, start, start + 1);
> - } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
> -out:
> - if (locked)
> - up_read(&mm->mmap_sem);
> - if (!ret)
> - ret = -EFAULT;
> - if (ret > 0)
> - vec->nr_frames = ret;
> - return ret;
> -}
> -EXPORT_SYMBOL(get_vaddr_frames);
> -
> -/**
> - * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
> - * them
> - * @vec: frame vector to put
> - *
> - * Drop references to pages if get_vaddr_frames() acquired them. We also
> - * invalidate the frame vector so that it is prepared for the next call into
> - * get_vaddr_frames().
> - */
> -void put_vaddr_frames(struct frame_vector *vec)
> -{
> - int i;
> - struct page **pages;
> -
> - if (!vec->got_ref)
> - goto out;
> - pages = frame_vector_pages(vec);
> - /*
> - * frame_vector_pages() might needed to do a conversion when
> - * get_vaddr_frames() got pages but vec was later converted to pfns.
> - * But it shouldn't really fail to convert pfns back...
> - */
> - if (WARN_ON(IS_ERR(pages)))
> - goto out;
> - for (i = 0; i < vec->nr_frames; i++)
> - put_page(pages[i]);
> - vec->got_ref = false;
> -out:
> - vec->nr_frames = 0;
> -}
> -EXPORT_SYMBOL(put_vaddr_frames);
> -
> -/**
> - * frame_vector_to_pages - convert frame vector to contain page pointers
> - * @vec: frame vector to convert
> - *
> - * Convert @vec to contain array of page pointers. If the conversion is
> - * successful, return 0. Otherwise return an error. Note that we do not grab
> - * page references for the page structures.
> - */
> -int frame_vector_to_pages(struct frame_vector *vec)
> -{
> - int i;
> - unsigned long *nums;
> - struct page **pages;
> -
> - if (!vec->is_pfns)
> - return 0;
> - nums = frame_vector_pfns(vec);
> - for (i = 0; i < vec->nr_frames; i++)
> - if (!pfn_valid(nums[i]))
> - return -EINVAL;
> - pages = (struct page **)nums;
> - for (i = 0; i < vec->nr_frames; i++)
> - pages[i] = pfn_to_page(nums[i]);
> - vec->is_pfns = false;
> - return 0;
> -}
> -EXPORT_SYMBOL(frame_vector_to_pages);
> -
> -/**
> - * frame_vector_to_pfns - convert frame vector to contain pfns
> - * @vec: frame vector to convert
> - *
> - * Convert @vec to contain array of pfns.
> - */
> -void frame_vector_to_pfns(struct frame_vector *vec)
> -{
> - int i;
> - unsigned long *nums;
> - struct page **pages;
> -
> - if (vec->is_pfns)
> - return;
> - pages = (struct page **)(vec->ptrs);
> - nums = (unsigned long *)pages;
> - for (i = 0; i < vec->nr_frames; i++)
> - nums[i] = page_to_pfn(pages[i]);
> - vec->is_pfns = true;
> -}
> -EXPORT_SYMBOL(frame_vector_to_pfns);
> -
> -/**
> - * frame_vector_create() - allocate & initialize structure for pinned pfns
> - * @nr_frames: number of pfns slots we should reserve
> - *
> - * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
> - * pfns.
> - */
> -struct frame_vector *frame_vector_create(unsigned int nr_frames)
> -{
> - struct frame_vector *vec;
> - int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
> -
> - if (WARN_ON_ONCE(nr_frames == 0))
> - return NULL;
> - /*
> - * This is absurdly high. It's here just to avoid strange effects when
> - * arithmetics overflows.
> - */
> - if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
> - return NULL;
> - /*
> - * Avoid higher order allocations, use vmalloc instead. It should
> - * be rare anyway.
> - */
> - if (size <= PAGE_SIZE)
> - vec = kmalloc(size, GFP_KERNEL);
> - else
> - vec = vmalloc(size);
> - if (!vec)
> - return NULL;
> - vec->nr_allocated = nr_frames;
> - vec->nr_frames = 0;
> - return vec;
> -}
> -EXPORT_SYMBOL(frame_vector_create);
> -
> -/**
> - * frame_vector_destroy() - free memory allocated to carry frame vector
> - * @vec: Frame vector to free
> - *
> - * Free structure allocated by frame_vector_create() to carry frames.
> - */
> -void frame_vector_destroy(struct frame_vector *vec)
> -{
> - /* Make sure put_vaddr_frames() got called properly... */
> - VM_BUG_ON(vec->nr_frames > 0);
> - if (!is_vmalloc_addr(vec))
> - kfree(vec);
> - else
> - vfree(vec);
> -}
> -EXPORT_SYMBOL(frame_vector_destroy);
> -
> /**
> * get_dump_page() - pin user page in memory while writing it to core dump
> * @addr: user address
> --
> 2.4.2
>
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