Merge tag 'pm-fixes-for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Power management fixes for 3.3

Two fixes for regressions introduced during the merge window, one fix for
a long-standing obscure issue in the computation of hibernate image size
and two small PM documentation fixes.

* tag 'pm-fixes-for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / Sleep: Fix read_unlock_usermodehelper() call.
  PM / Hibernate: Rewrite unlock_system_sleep() to fix s2disk regression
  PM / Hibernate: Correct additional pages number calculation
  PM / Documentation: Fix minor issue in freezing_of_tasks.txt
  PM / Documentation: Fix spelling mistake in basic-pm-debugging.txt

1 files changed, 17 insertions, 2 deletions

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 95040cc3310..91784a4f860 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -357,14 +357,29 @@ extern bool pm_save_wakeup_count(unsigned int count);
 
 static inline void lock_system_sleep(void)
 {
-        freezer_do_not_count();
+        current->flags |= PF_FREEZER_SKIP;
         mutex_lock(&pm_mutex);
 }
 
 static inline void unlock_system_sleep(void)
 {
+        /*
+         * Don't use freezer_count() because we don't want the call to
+         * try_to_freeze() here.
+         *
+         * Reason:
+         * Fundamentally, we just don't need it, because freezing condition
+         * doesn't come into effect until we release the pm_mutex lock,
+         * since the freezer always works with pm_mutex held.
+         *
+         * More importantly, in the case of hibernation,
+         * unlock_system_sleep() gets called in snapshot_read() and
+         * snapshot_write() when the freezing condition is still in effect.
+         * Which means, if we use try_to_freeze() here, it would make them
+         * enter the refrigerator, thus causing hibernation to lockup.
+         */
+        current->flags &= ~PF_FREEZER_SKIP;
         mutex_unlock(&pm_mutex);
-        freezer_count();
 }
 
 #else /* !CONFIG_PM_SLEEP */