freezer: unexport refrigerator() and update try_to_freeze() slightly

There is no reason to export two functions for entering the
refrigerator.  Calling refrigerator() instead of try_to_freeze()
doesn't save anything noticeable or removes any race condition.

* Rename refrigerator() to __refrigerator() and make it return bool
  indicating whether it scheduled out for freezing.

* Update try_to_freeze() to return bool and relay the return value of
  __refrigerator() if freezing().

* Convert all refrigerator() users to try_to_freeze().

* Update documentation accordingly.

* While at it, add might_sleep() to try_to_freeze().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Christoph Hellwig <hch@infradead.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/kernel/freezer.c b/kernel/freezer.c
index 3f460104a9d6..732f14f5944f 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -23,10 +23,11 @@ static inline void frozen_process(void)
 }
 
 /* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(void)
+bool __refrigerator(void)
 {
         /* Hmm, should we be allowed to suspend when there are realtime
            processes around? */
+        bool was_frozen = false;
         long save;
 
         task_lock(current);
@@ -35,7 +36,7 @@ void refrigerator(void)
                 task_unlock(current);
         } else {
                 task_unlock(current);
-                return;
+                return was_frozen;
         }
         save = current->state;
         pr_debug("%s entered refrigerator\n", current->comm);
@@ -51,6 +52,7 @@ void refrigerator(void)
                 set_current_state(TASK_UNINTERRUPTIBLE);
                 if (!frozen(current))
                         break;
+                was_frozen = true;
                 schedule();
         }
 
@@ -65,8 +67,10 @@ void refrigerator(void)
          * synchronization which depends on ordered task state change.
          */
         set_current_state(save);
+
+        return was_frozen;
 }
-EXPORT_SYMBOL(refrigerator);
+EXPORT_SYMBOL(__refrigerator);
 
 static void fake_signal_wake_up(struct task_struct *p)
 {