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| author | Jonas Meurer <jonas@freesources.org> | 2020-01-16 12:53:54 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2020-01-16 21:47:03 +0100 |
| commit | c052bf82c6b00ca27aab0859addc4b3159dfd3a4 (patch) | |
| tree | 5d705708933306bc2c9600133255c8110869bd3a /Documentation/ABI | |
| parent | 5c0e9de06577ba7599b75f97a8bb8cc63f6cb2ad (diff) | |
| download | linux-c052bf82c6b00ca27aab0859addc4b3159dfd3a4.tar.bz2 | |
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 <jonas@freesources.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-power | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 6f87b9dd384b..5e6ead29124c 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -407,3 +407,16 @@ Contact: Kalesh Singh <kaleshsingh96@gmail.com> Description: The /sys/power/suspend_stats/last_failed_step file contains the last failed step in the suspend/resume path. + +What: /sys/power/sync_on_suspend +Date: October 2019 +Contact: Jonas Meurer <jonas@freesources.org> +Description: + This file controls whether or not the kernel will sync() + filesystems during system suspend (after freezing user space + and before suspending devices). + + Writing a "1" to this file enables the sync() and writing a "0" + disables it. Reads from the file return the current value. + The default is "1" if the build-time "SUSPEND_SKIP_SYNC" config + flag is unset, or "0" otherwise. |