From c052bf82c6b00ca27aab0859addc4b3159dfd3a4 Mon Sep 17 00:00:00 2001 From: Jonas Meurer Date: Thu, 16 Jan 2020 12:53:54 +0100 Subject: PM: suspend: Add sysfs attribute to control the "sync on suspend" behavior The sysfs attribute `/sys/power/sync_on_suspend` controls, whether or not filesystems are synced by the kernel before system suspend. Congruously, the behaviour of build-time switch CONFIG_SUSPEND_SKIP_SYNC is slightly changed: It now defines the run-tim default for the new sysfs attribute `/sys/power/sync_on_suspend`. The run-time attribute is added because the existing corresponding build-time Kconfig flag for (`CONFIG_SUSPEND_SKIP_SYNC`) is not flexible enough. E.g. Linux distributions that provide pre-compiled kernels usually want to stick with the default (sync filesystems before suspend) but under special conditions this needs to be changed. One example for such a special condition is user-space handling of suspending block devices (e.g. using `cryptsetup luksSuspend` or `dmsetup suspend`) before system suspend. The Kernel trying to sync filesystems after the underlying block device already got suspended obviously leads to dead-locks. Be aware that you have to take care of the filesystem sync yourself before suspending the system in those scenarios. Signed-off-by: Jonas Meurer Signed-off-by: Rafael J. Wysocki --- include/linux/suspend.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/suspend.h') diff --git a/include/linux/suspend.h b/include/linux/suspend.h index 6fc8843f1c9e..4a230c2f1c31 100644 --- a/include/linux/suspend.h +++ b/include/linux/suspend.h @@ -329,6 +329,7 @@ extern void arch_suspend_disable_irqs(void); extern void arch_suspend_enable_irqs(void); extern int pm_suspend(suspend_state_t state); +extern bool sync_on_suspend_enabled; #else /* !CONFIG_SUSPEND */ #define suspend_valid_only_mem NULL @@ -342,6 +343,7 @@ static inline bool pm_suspend_default_s2idle(void) { return false; } static inline void suspend_set_ops(const struct platform_suspend_ops *ops) {} static inline int pm_suspend(suspend_state_t state) { return -ENOSYS; } +static inline bool sync_on_suspend_enabled(void) { return true; } static inline bool idle_should_enter_s2idle(void) { return false; } static inline void __init pm_states_init(void) {} static inline void s2idle_set_ops(const struct platform_s2idle_ops *ops) {} -- cgit