Kernel bump from 4.1.3-rt to 4.1.7-rt.

[kvmfornfv.git] / kernel / fs / notify / mark.c

diff --git a/kernel/fs/notify/mark.c b/kernel/fs/notify/mark.c
index 92e48c7..39ddcaf 100644 (file)
--- a/kernel/fs/notify/mark.c
+++ b/kernel/fs/notify/mark.c
@@ -412,16 +412,36 @@ void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
                                         unsigned int flags)
 {
        struct fsnotify_mark *lmark, *mark;
+       LIST_HEAD(to_free);
 
+       /*
+        * We have to be really careful here. Anytime we drop mark_mutex, e.g.
+        * fsnotify_clear_marks_by_inode() can come and free marks. Even in our
+        * to_free list so we have to use mark_mutex even when accessing that
+        * list. And freeing mark requires us to drop mark_mutex. So we can
+        * reliably free only the first mark in the list. That's why we first
+        * move marks to free to to_free list in one go and then free marks in
+        * to_free list one by one.
+        */
        mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
        list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
-               if (mark->flags & flags) {
-                       fsnotify_get_mark(mark);
-                       fsnotify_destroy_mark_locked(mark, group);
-                       fsnotify_put_mark(mark);
-               }
+               if (mark->flags & flags)
+                       list_move(&mark->g_list, &to_free);
        }
        mutex_unlock(&group->mark_mutex);
+
+       while (1) {
+               mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
+               if (list_empty(&to_free)) {
+                       mutex_unlock(&group->mark_mutex);
+                       break;
+               }
+               mark = list_first_entry(&to_free, struct fsnotify_mark, g_list);
+               fsnotify_get_mark(mark);
+               fsnotify_destroy_mark_locked(mark, group);
+               mutex_unlock(&group->mark_mutex);
+               fsnotify_put_mark(mark);
+       }
 }
 
 /*