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mm: replace get_vaddr_frames() write/force parameters with gup_flags

This removes the 'write' and 'force' from get_vaddr_frames() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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lorenzo-stoakes authored and torvalds committed Oct 13, 2016
1 parent 3b91317 commit 7f23b3504a0df63b724180262c5f3f117f21bcae
@@ -488,7 +488,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
goto err_free;
}
ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
g2d_userptr->vec);
if (ret != npages) {
DRM_ERROR("failed to get user pages from userptr.\n");
if (ret < 0)
@@ -214,7 +214,7 @@ static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp,
if (!vec)
return -ENOMEM;
ret = get_vaddr_frames(virtp, 1, true, false, vec);
ret = get_vaddr_frames(virtp, 1, FOLL_WRITE, vec);
if (ret != 1) {
frame_vector_destroy(vec);
return -EINVAL;
@@ -42,14 +42,18 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
unsigned long first, last;
unsigned long nr;
struct frame_vector *vec;
unsigned int flags = FOLL_FORCE;
if (write)
flags |= FOLL_WRITE;
first = start >> PAGE_SHIFT;
last = (start + length - 1) >> PAGE_SHIFT;
nr = last - first + 1;
vec = frame_vector_create(nr);
if (!vec)
return ERR_PTR(-ENOMEM);
ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec);
ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
if (ret < 0)
goto out_destroy;
/* We accept only complete set of PFNs */
@@ -1305,7 +1305,7 @@ struct frame_vector {
struct frame_vector *frame_vector_create(unsigned int nr_frames);
void frame_vector_destroy(struct frame_vector *vec);
int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
bool write, bool force, struct frame_vector *vec);
unsigned int gup_flags, struct frame_vector *vec);
void put_vaddr_frames(struct frame_vector *vec);
int frame_vector_to_pages(struct frame_vector *vec);
void frame_vector_to_pfns(struct frame_vector *vec);
@@ -11,10 +11,7 @@
* 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().
* @gup_flags: flags modifying lookup behaviour
* @vec: structure which receives pages / pfns of the addresses mapped.
* It should have space for at least nr_frames entries.
*
@@ -34,23 +31,17 @@
* 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)
unsigned int gup_flags, struct frame_vector *vec)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int ret = 0;
int err;
int locked;
unsigned int gup_flags = 0;
if (nr_frames == 0)
return 0;
if (write)
gup_flags |= FOLL_WRITE;
if (force)
gup_flags |= FOLL_FORCE;
if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
nr_frames = vec->nr_allocated;

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