Merge branch 'pm-sleep'

Merge updates related to system suspend and hibernation for 6.19-rc1:

 - Replace snprintf() with scnprintf() in show_trace_dev_match()
   (Kaushlendra Kumar)

 - Fix memory allocation error handling in pm_vt_switch_required()
   (Malaya Kumar Rout)

 - Introduce CALL_PM_OP() macro and use it to simplify code in
   generic PM operations (Kaushlendra Kumar)

 - Add module param to backtrace all CPUs in the device power management
   watchdog (Sergey Senozhatsky)

 - Rework message printing in swsusp_save() (Rafael Wysocki)

 - Make it possible to change the number of hibernation compression
   threads (Xueqin Luo)

 - Clarify that only cgroup1 freezer uses PM freezer (Tejun Heo)

 - Add document on debugging shutdown hangs to PM documentation and
   correct a mistaken configuration option in it (Mario Limonciello)

 - Shut down wakeup source timer before removing the wakeup source from
   the list (Kaushlendra Kumar, Rafael Wysocki)

 - Introduce new PMSG_POWEROFF event for system shutdown handling with
   the help of PM device callbacks (Mario Limonciello)

 - Make pm_test delay interruptible by wakeup events (Riwen Lu)

 - Clean up kernel-doc comment style usage in the core hibernation
   code and remove unuseful comments from it (Sunday Adelodun, Rafael
   Wysocki)

 - Add support for handling wakeup events and aborting the suspend
   process while it is syncing file systems (Samuel Wu, Rafael Wysocki)

* pm-sleep: (21 commits)
  PM: hibernate: Extra cleanup of comments in swap handling code
  PM: sleep: Call pm_sleep_fs_sync() instead of ksys_sync_helper()
  PM: sleep: Add support for wakeup during filesystem sync
  PM: hibernate: Clean up kernel-doc comment style usage
  PM: suspend: Make pm_test delay interruptible by wakeup events
  usb: sl811-hcd: Add PM_EVENT_POWEROFF into suspend callbacks
  scsi: Add PM_EVENT_POWEROFF into suspend callbacks
  PM: Introduce new PMSG_POWEROFF event
  PM: wakeup: Update after recent wakeup source removal ordering change
  PM: wakeup: Delete timer before removing wakeup source from list
  Documentation: power: Correct a mistaken configuration option
  Documentation: power: Add document on debugging shutdown hangs
  freezer: Clarify that only cgroup1 freezer uses PM freezer
  PM: hibernate: add sysfs interface for hibernate_compression_threads
  PM: hibernate: make compression threads configurable
  PM: hibernate: dynamically allocate crc->unc_len/unc for configurable threads
  PM: hibernate: Rework message printing in swsusp_save()
  PM: dpm_watchdog: add module param to backtrace all CPUs
  PM: sleep: Introduce CALL_PM_OP() macro to simplify code
  PM: console: Fix memory allocation error handling in pm_vt_switch_required()
  ...

2 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/power/index.rst b/Documentation/power/index.rst
index a0f5244fb427..ea70633d9ce6 100644
--- a/Documentation/power/index.rst
+++ b/Documentation/power/index.rst
@@ -19,6 +19,7 @@ Power Management
     power_supply_class
     runtime_pm
     s2ram
+    shutdown-debugging
     suspend-and-cpuhotplug
     suspend-and-interrupts
     swsusp-and-swap-files
diff --git a/Documentation/power/shutdown-debugging.rst b/Documentation/power/shutdown-debugging.rst
new file mode 100644
index 000000000000..c510122e0bbc
--- /dev/null
+++ b/Documentation/power/shutdown-debugging.rst
@@ -0,0 +1,53 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Debugging Kernel Shutdown Hangs with pstore
++++++++++++++++++++++++++++++++++++++++++++
+
+Overview
+========
+If the system hangs while shutting down, the kernel logs may need to be
+retrieved to debug the issue.
+
+On systems that have a UART available, it is best to configure the kernel to use
+this UART for kernel console output.
+
+If a UART isn't available, the ``pstore`` subsystem provides a mechanism to
+persist this data across a system reset, allowing it to be retrieved on the next
+boot.
+
+Kernel Configuration
+====================
+To enable ``pstore`` and enable saving kernel ring buffer logs, set the
+following kernel configuration options:
+
+* ``CONFIG_PSTORE=y``
+* ``CONFIG_PSTORE_CONSOLE=y``
+
+Additionally, enable a backend to store the data. Depending upon your platform
+some potential options include:
+
+* ``CONFIG_EFI_VARS_PSTORE=y``
+* ``CONFIG_PSTORE_RAM=y``
+* ``CONFIG_CHROMEOS_PSTORE=y``
+* ``CONFIG_PSTORE_BLK=y``
+
+Kernel Command-line Parameters
+==============================
+Add these parameters to your kernel command line:
+
+* ``printk.always_kmsg_dump=Y``
+	* Forces the kernel to dump the entire message buffer to pstore during
+		shutdown
+* ``efi_pstore.pstore_disable=N``
+	* For EFI-based systems, ensures the EFI backend is active
+
+Userspace Interaction and Log Retrieval
+=======================================
+On the next boot after a hang, pstore logs will be available in the pstore
+filesystem (``/sys/fs/pstore``) and can be retrieved by userspace.
+
+On systemd systems, the ``systemd-pstore`` service will help do the following:
+
+#. Locate pstore data in ``/sys/fs/pstore``
+#. Read and save it to ``/var/lib/systemd/pstore``
+#. Clear pstore data for the next event