mm: remove write/force parameters from __get_user_pages_locked()

This removes the redundant 'write' and 'force' parameters from __get_user_pages_locked() 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 <[email protected]> Reviewed-by: Jan Kara <[email protected]> Acked-by: Michal Hocko <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
imcsk8 · Oct 18, 2016 · 859110d · 859110d
1 parent 19be0ea
commit 859110d
Showing 1 changed file with 33 additions and 14 deletions.
diff --git a/mm/gup.c b/mm/gup.c
@@ -739,7 +739,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 						struct mm_struct *mm,
 						unsigned long start,
 						unsigned long nr_pages,
-						int write, int force,
 						struct page **pages,
 						struct vm_area_struct **vmas,
 						int *locked, bool notify_drop,
@@ -757,10 +756,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 
 	if (pages)
 		flags |= FOLL_GET;
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
 
 	pages_done = 0;
 	lock_dropped = false;
@@ -856,9 +851,15 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 			   int write, int force, struct page **pages,
 			   int *locked)
 {
+	unsigned int flags = FOLL_TOUCH;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       write, force, pages, NULL, locked, true,
-				       FOLL_TOUCH);
+				       pages, NULL, locked, true, flags);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
@@ -879,9 +880,15 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
 {
 	long ret;
 	int locked = 1;
+
+	if (write)
+		gup_flags |= FOLL_WRITE;
+	if (force)
+		gup_flags |= FOLL_FORCE;
+
 	down_read(&mm->mmap_sem);
-	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
-				      pages, NULL, &locked, false, gup_flags);
+	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,
+				      &locked, false, gup_flags);
 	if (locked)
 		up_read(&mm->mmap_sem);
 	return ret;
@@ -973,9 +980,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 		int write, 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 | FOLL_REMOTE);
+	unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
+	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+				       NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
@@ -989,9 +1002,15 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 		int write, int force, struct page **pages,
 		struct vm_area_struct **vmas)
 {
+	unsigned int flags = FOLL_TOUCH;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       write, force, pages, vmas, NULL, false,
-				       FOLL_TOUCH);
+				       pages, vmas, NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages);