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Date: Mon, 16 Nov 2015 19:35:16 -0800
From: Dave Hansen <dave@...1.net>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, Dave Hansen <dave@...1.net>,
dave.hansen@...ux.intel.com, akpm@...ux-foundation.org,
kirill.shutemov@...ux.intel.com, aarcange@...hat.com,
n-horiguchi@...jp.nec.com
Subject: [PATCH 04/37] mm: simplify __get_user_pages()
From: Dave Hansen <dave.hansen@...ux.intel.com>
Now that we have one fewer callers of __get_user_pages(), we only
have one way in which it is called. Neither of the two remaining
callers need to pass 'locked' nor set notify_drop=1. We can drop
both those arguments.
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
b/mm/gup.c | 39 ++++++++-------------------------------
1 file changed, 8 insertions(+), 31 deletions(-)
diff -puN mm/gup.c~simplify-get_user_pages mm/gup.c
--- a/mm/gup.c~simplify-get_user_pages 2015-11-16 12:35:36.119207285 -0800
+++ b/mm/gup.c 2015-11-16 12:35:36.123207466 -0800
@@ -625,18 +625,10 @@ static __always_inline long __get_user_p
int write, int force,
struct page **pages,
struct vm_area_struct **vmas,
- int *locked, bool notify_drop,
unsigned int flags)
{
+ int locked = 1;
long ret, pages_done;
- bool lock_dropped;
-
- if (locked) {
- /* if VM_FAULT_RETRY can be returned, vmas become invalid */
- BUG_ON(vmas);
- /* check caller initialized locked */
- BUG_ON(*locked != 1);
- }
if (pages)
flags |= FOLL_GET;
@@ -646,16 +638,12 @@ static __always_inline long __get_user_p
flags |= FOLL_FORCE;
pages_done = 0;
- lock_dropped = false;
for (;;) {
ret = __get_user_pages(tsk, mm, start, nr_pages, flags, pages,
- vmas, locked);
- if (!locked)
- /* VM_FAULT_RETRY couldn't trigger, bypass */
- return ret;
+ vmas, &locked);
/* VM_FAULT_RETRY cannot return errors */
- if (!*locked) {
+ if (!locked) {
BUG_ON(ret < 0);
BUG_ON(ret >= nr_pages);
}
@@ -670,7 +658,7 @@ static __always_inline long __get_user_p
if (!nr_pages)
break;
}
- if (*locked) {
+ if (locked) {
/* VM_FAULT_RETRY didn't trigger */
if (!pages_done)
pages_done = ret;
@@ -685,8 +673,7 @@ static __always_inline long __get_user_p
* without FAULT_FLAG_ALLOW_RETRY but with
* FAULT_FLAG_TRIED.
*/
- *locked = 1;
- lock_dropped = true;
+ locked = 1;
down_read(&mm->mmap_sem);
ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
pages, NULL, NULL);
@@ -703,14 +690,6 @@ static __always_inline long __get_user_p
pages++;
start += PAGE_SIZE;
}
- if (notify_drop && lock_dropped && *locked) {
- /*
- * We must let the caller know we temporarily dropped the lock
- * and so the critical section protected by it was lost.
- */
- up_read(&mm->mmap_sem);
- *locked = 0;
- }
return pages_done;
}
@@ -730,12 +709,10 @@ __always_inline long __get_user_pages_un
unsigned int gup_flags)
{
long ret;
- int locked = 1;
down_read(&mm->mmap_sem);
ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, NULL, &locked, false, gup_flags);
- if (locked)
- up_read(&mm->mmap_sem);
+ pages, NULL, gup_flags);
+ up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL(__get_user_pages_unlocked);
@@ -826,7 +803,7 @@ long get_user_pages(struct task_struct *
int force, struct page **pages, struct vm_area_struct **vmas)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, vmas, NULL, false, FOLL_TOUCH);
+ pages, vmas, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages);
_
--
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