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authorBart Van Assche <bart.vanassche@wdc.com>2018-01-05 09:19:08 -0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-01-10 01:07:46 +0100
commit4bf236a3330e97d275e5848420f7e31948fef07a (patch)
tree0be93c72c34a05451c4fd8bdb9c57d84dd06720a /kernel/power
parentbdbc98abb3aa323f6323b11db39c740e6f8fc5b1 (diff)
PM / sleep: Make lock/unlock_system_sleep() available to kernel modules
Since pm_mutex is not exported using lock/unlock_system_sleep() from inside a kernel module causes a "pm_mutex undefined" linker error. Hence move lock/unlock_system_sleep() into kernel/power/main.c and export these. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'kernel/power')
-rw-r--r--kernel/power/main.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 3a2ca9066583..705c2366dafe 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -22,6 +22,35 @@ DEFINE_MUTEX(pm_mutex);
#ifdef CONFIG_PM_SLEEP
+void lock_system_sleep(void)
+{
+ current->flags |= PF_FREEZER_SKIP;
+ mutex_lock(&pm_mutex);
+}
+EXPORT_SYMBOL_GPL(lock_system_sleep);
+
+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);
+}
+EXPORT_SYMBOL_GPL(unlock_system_sleep);
+
/* Routines for PM-transition notifications */
static BLOCKING_NOTIFIER_HEAD(pm_chain_head);