Some subsystem resume callbacks do not receive the PM event and
therefore cannot distinguish the PMSG_THAW phase after snapshot creation
from the PMSG_RESTORE phase.
Export pm_hibernation_snapshot_done() so a driver can query whether the
hibernation snapshot has been created and is still available. The helper
only exposes the PM state; callers remain responsible for ensuring that
any device-specific behavior is safe, including subsequent poweroff or
shutdown handling.
The helper returns !!in_suspend. This variable is set before
swsusp_arch_suspend(), cleared before the snapshot memory is released,
and marked __nosavedata, so it remains clear on the restore path.
Signed-off-by: Haowen Tu <redacted>
Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
---
include/linux/suspend.h | 2 ++
kernel/power/hibernate.c | 12 ++++++++++++
2 files changed, 14 insertions(+)
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index b02876f1ae38..2cebbec3e2f7 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -393,6 +393,7 @@ extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
extern int hibernate(void);
extern bool system_entering_hibernation(void);
extern bool hibernation_available(void);
+bool pm_hibernation_snapshot_done(void);
asmlinkage int swsusp_save(void);
extern struct pbe *restore_pblist;
int pfn_is_nosave(unsigned long pfn);
@@ -412,6 +413,7 @@ static inline void hibernation_set_ops(const struct platform_hibernation_ops *op
static inline int hibernate(void) { return -ENOSYS; }
static inline bool system_entering_hibernation(void) { return false; }
static inline bool hibernation_available(void) { return false; }
+static inline bool pm_hibernation_snapshot_done(void) { return false; }
static inline int hibernate_quiet_exec(int (*func)(void *data), void *data) {
return -ENOTSUPP;diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 6d3e637c5a02..045d29f55011 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -113,6 +113,18 @@ bool hibernation_available(void)
!secretmem_active() && !cxl_mem_active();
}
+/**
+ * pm_hibernation_snapshot_done - check if a hibernation snapshot is available
+ *
+ * Return: %true if a hibernation snapshot has been taken and has not been
+ * released yet.
+ */
+bool pm_hibernation_snapshot_done(void)
+{
+ return !!in_suspend;
+}
+EXPORT_SYMBOL_GPL(pm_hibernation_snapshot_done);
+
/**
* hibernation_set_ops - Set the global hibernate operations.
* @ops: Hibernation operations to use in subsequent hibernation transitions.--
2.20.1