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-rw-r--r--kernel/power/main.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/kernel/power/main.c b/kernel/power/main.c
index daa535012e51..f6425ae3e8b0 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -21,6 +21,33 @@
#include "power.h"
#ifdef CONFIG_PM_SLEEP
+/*
+ * The following functions are used by the suspend/hibernate code to temporarily
+ * change gfp_allowed_mask in order to avoid using I/O during memory allocations
+ * while devices are suspended. To avoid races with the suspend/hibernate code,
+ * they should always be called with system_transition_mutex held
+ * (gfp_allowed_mask also should only be modified with system_transition_mutex
+ * held, unless the suspend/hibernate code is guaranteed not to run in parallel
+ * with that modification).
+ */
+static gfp_t saved_gfp_mask;
+
+void pm_restore_gfp_mask(void)
+{
+ WARN_ON(!mutex_is_locked(&system_transition_mutex));
+ if (saved_gfp_mask) {
+ gfp_allowed_mask = saved_gfp_mask;
+ saved_gfp_mask = 0;
+ }
+}
+
+void pm_restrict_gfp_mask(void)
+{
+ WARN_ON(!mutex_is_locked(&system_transition_mutex));
+ WARN_ON(saved_gfp_mask);
+ saved_gfp_mask = gfp_allowed_mask;
+ gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
+}
unsigned int lock_system_sleep(void)
{