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mm/gup: introduce pin_user_pages_fast_only()

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This is the FOLL_PIN equivalent of __get_user_pages_fast(), except with a
more descriptive name, and gup_flags instead of a boolean "write" in the
argument list.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://lkml.kernel.org/r/20200519002124.2025955-4-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
John Hubbard 2020-06-03 15:56:34 -07:00 committed by Linus Torvalds
parent 376a34efa4
commit 104acc3276
2 changed files with 38 additions and 0 deletions
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2
include/linux/mm.h
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@ -1827,6 +1827,8 @@ extern int mprotect_fixup(struct vm_area_struct *vma,
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
int pin_user_pages_fast_only(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages);
/*
* per-process(per-mm_struct) statistics.
*/

36
mm/gup.c
View File

@ -2917,6 +2917,42 @@ int pin_user_pages_fast(unsigned long start, int nr_pages,
}
EXPORT_SYMBOL_GPL(pin_user_pages_fast);
/*
* This is the FOLL_PIN equivalent of __get_user_pages_fast(). Behavior is the
* same, except that this one sets FOLL_PIN instead of FOLL_GET.
*
* The API rules are the same, too: no negative values may be returned.
*/
int pin_user_pages_fast_only(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
{
int nr_pinned;
/*
* FOLL_GET and FOLL_PIN are mutually exclusive. Note that the API
* rules require returning 0, rather than -errno:
*/
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return 0;
/*
* FOLL_FAST_ONLY is required in order to match the API description of
* this routine: no fall back to regular ("slow") GUP.
*/
gup_flags |= (FOLL_PIN | FOLL_FAST_ONLY);
nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
pages);
/*
* This routine is not allowed to return negative values. However,
* internal_get_user_pages_fast() *can* return -errno. Therefore,
* correct for that here:
*/
if (nr_pinned < 0)
nr_pinned = 0;
return nr_pinned;
}
EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
/**
* pin_user_pages_remote() - pin pages of a remote process (task != current)
*