Merge branch 'freezer'

* freezer:
  af_unix: use freezable blocking calls in read
  sigtimedwait: use freezable blocking call
  nanosleep: use freezable blocking call
  futex: use freezable blocking call
  select: use freezable blocking call
  epoll: use freezable blocking call
  binder: use freezable blocking calls
  freezer: add new freezable helpers using freezer_do_not_count()
  freezer: convert freezable helpers to static inline where possible
  freezer: convert freezable helpers to freezer_do_not_count()
  freezer: skip waking up tasks with PF_FREEZER_SKIP set
  freezer: shorten freezer sleep time using exponential backoff
  lockdep: check that no locks held at freeze time
  lockdep: remove task argument from debug_check_no_locks_held
  freezer: add unsafe versions of freezable helpers for CIFS
  freezer: add unsafe versions of freezable helpers for NFS

1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/freezer.c b/kernel/freezer.c
index c38893b0efba..8b2afc1c9df0 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -110,6 +110,18 @@ bool freeze_task(struct task_struct *p)
 {
 	unsigned long flags;
 
+	/*
+	 * This check can race with freezer_do_not_count, but worst case that
+	 * will result in an extra wakeup being sent to the task.  It does not
+	 * race with freezer_count(), the barriers in freezer_count() and
+	 * freezer_should_skip() ensure that either freezer_count() sees
+	 * freezing == true in try_to_freeze() and freezes, or
+	 * freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task
+	 * normally.
+	 */
+	if (freezer_should_skip(p))
+		return false;
+
 	spin_lock_irqsave(&freezer_lock, flags);
 	if (!freezing(p) || frozen(p)) {
 		spin_unlock_irqrestore(&freezer_lock, flags);