mm: replace get_user_pages_locked() write/force parameters with gup_f…

…lags This removes the 'write' and 'force' use from get_user_pages_locked() 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 <[email protected]> Acked-by: Michal Hocko <[email protected]> Reviewed-by: Jan Kara <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
fracktal · Oct 19, 2016 · 3b91317 · 3b91317
1 parent c164154
commit 3b91317
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Showing 4 changed files with 15 additions and 12 deletions.
diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    int write, int force, struct page **pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-		    int write, int force, struct page **pages, int *locked);
+		    unsigned int gup_flags, struct page **pages, int *locked);
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
 			       struct page **pages, unsigned int gup_flags);

diff --git a/mm/frame_vector.c b/mm/frame_vector.c
@@ -41,10 +41,16 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 	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;
 
@@ -59,7 +65,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 		vec->got_ref = true;
 		vec->is_pfns = false;
 		ret = get_user_pages_locked(start, nr_frames,
-			write, force, (struct page **)(vec->ptrs), &locked);
+			gup_flags, (struct page **)(vec->ptrs), &locked);
 		goto out;
 	}
 

diff --git a/mm/gup.c b/mm/gup.c
@@ -848,18 +848,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
  *          up_read(&mm->mmap_sem);
  */
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   int write, int force, struct page **pages,
+			   unsigned int gup_flags, 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,
-				       pages, NULL, locked, true, flags);
+				       pages, NULL, locked, true,
+				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 

diff --git a/mm/nommu.c b/mm/nommu.c
@@ -176,9 +176,12 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 EXPORT_SYMBOL(get_user_pages);
 
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages,
+			    unsigned int gup_flags, struct page **pages,
 			    int *locked)
 {
+	int write = gup_flags & FOLL_WRITE;
+	int force = gup_flags & FOLL_FORCE;
+
 	return get_user_pages(start, nr_pages, write, force, pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);