wireguard-linux/kernel/power/suspend.c, branch jd/orphan-parallel

notifier: Fix broken error handling pattern

2020-09-01T07:58:03Z

The current notifiers have the following error handling pattern all over the place: int err, nr; err = __foo_notifier_call_chain(&chain, val_up, v, -1, &nr); if (err & NOTIFIER_STOP_MASK) __foo_notifier_call_chain(&chain, val_down, v, nr-1, NULL) And aside from the endless repetition thereof, it is broken. Consider blocking notifiers; both calls take and drop the rwsem, this means that the notifier list can change in between the two calls, making @nr meaningless. Fix this by replacing all the __foo_notifier_call_chain() functions with foo_notifier_call_chain_robust() that embeds the above pattern, but ensures it is inside a single lock region. Note: I switched atomic_notifier_call_chain_robust() to use the spinlock, since RCU cannot provide the guarantee required for the recovery. Note: software_resume() error handling was broken afaict. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20200818135804.325626653@infradead.org

ACPI: PM: s2idle: Avoid possible race related to the EC GPE

2020-02-11T09:11:02Z

It is theoretically possible for the ACPI EC GPE to be set after the s2idle_ops->wake() called from s2idle_loop() has returned and before the subsequent pm_wakeup_pending() check is carried out. If that happens, the resulting wakeup event will cause the system to resume even though it may be a spurious one. To avoid that race, first make the ->wake() callback in struct platform_s2idle_ops return a bool value indicating whether or not to let the system resume and rearrange s2idle_loop() to use that value instad of the direct pm_wakeup_pending() call if ->wake() is present. Next, rework acpi_s2idle_wake() to process EC events and check pm_wakeup_pending() before re-arming the SCI for system wakeup to prevent it from triggering prematurely and add comments to that function to explain the rationale for the new code flow. Fixes: 56b991849009 ("PM: sleep: Simplify suspend-to-idle control flow") Cc: 5.4+ # 5.4+ Signed-off-by: Rafael J. Wysocki

PM: suspend: Add sysfs attribute to control the "sync on suspend" behavior

2020-01-16T20:47:03Z

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

PM: suspend: Fix platform_suspend_prepare_noirq()

2019-08-10T11:18:06Z

After commit ac9eafbe930a ("ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices"), a NULL pointer may be dereferenced if suspend-to-idle is attempted on a platform without "traditional" suspend support due to invalid fall-through in platform_suspend_prepare_noirq(). Fix that and while at it add missing braces in platform_resume_noirq(). Fixes: ac9eafbe930a ("ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices") Reported-by: Marek Szyprowski Signed-off-by: Rafael J. Wysocki

ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices

2019-08-08T09:26:01Z

According to Section 3.5 of the "Intel Low Power S0 Idle" document [1], Function 5 of the LPS0 _DSM is expected to be invoked when the system configuration matches the criteria for entering the target low-power state of the platform. In particular, this means that all devices should be suspended and in low-power states already when that function is invoked. This is not the case currently, however, because Function 5 of the LPS0 _DSM is invoked by it before the "noirq" phase of device suspend, which means that some devices may not have been put into low-power states yet at that point. That is a consequence of the previous design of the suspend-to-idle flow that allowed the "noirq" phase of device suspend and the "noirq" phase of device resume to be carried out for multiple times while "suspended" (if any spurious wakeup events were detected) and the point of the LPS0 _DSM Function 5 invocation was chosen so as to call it (and LPS0 _DSM Function 6 analogously) once per suspend-resume cycle (regardless of how many times the "noirq" phases of device suspend and resume were carried out while "suspended"). Now that the suspend-to-idle flow has been redesigned to carry out the "noirq" phases of device suspend and resume once in each cycle, the code can be reordered to follow the specification that it is based on more closely. For this purpose, add ->prepare_late and ->restore_early platform callbacks for suspend-to-idle, to be executed, respectively, after the "noirq" phase of suspending devices and before the "noirq" phase of resuming them and make ACPI use them for the invocation of LPS0 _DSM functions as appropriate. While at it, move the LPS0 entry requirements check to be made before invoking Functions 3 and 5 of the LPS0 _DSM (also once per cycle) as follows from the specification [1]. Link: https://uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf # [1] Signed-off-by: Rafael J. Wysocki Tested-by: Kai-Heng Feng

PM: sleep: Integrate suspend-to-idle with generig suspend flow

2019-07-23T07:46:50Z

After previous changes the suspend-to-idle code flow can be integrated more tightly with the generic system suspend code flow by making suspend_enter() call s2idle_loop() later and removing the direct invocations of dpm_noirq_begin(), dpm_noirq_suspend_devices(), dpm_noirq_end(), and dpm_noirq_resume_devices() from the latter, so do that. This change is not expected to alter functionality. Signed-off-by: Rafael J. Wysocki Acked-by: Thomas Gleixner

PM: sleep: Simplify suspend-to-idle control flow

2019-07-23T07:46:40Z

After commit 33e4f80ee69b ("ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle") the "noirq" phases of device suspend and resume may run for multiple times during suspend-to-idle, if there are spurious system wakeup events while suspended. However, this is complicated and fragile and actually unnecessary. The main reason for doing this is that on some systems the EC may signal system wakeup events (power button events, for example) as well as events that should not cause the system to resume (spurious system wakeup events). Thus, in order to determine whether or not a given event signaled by the EC while suspended is a proper system wakeup one, the EC GPE needs to be dispatched and to start with that was achieved by allowing the ACPI SCI action handler to run, which was only possible after calling resume_device_irqs(). However, dispatching the EC GPE this way turned out to take too much time in some cases and some EC events might be missed due to that, so commit 68e22011856f ("ACPI: EC: Dispatch the EC GPE directly on s2idle wake") started to dispatch the EC GPE right after a wakeup event has been detected, so in fact the full ACPI SCI action handler doesn't need to run any more to deal with the wakeups coming from the EC. Use this observation to simplify the suspend-to-idle control flow so that the "noirq" phases of device suspend and resume are each run only once in every suspend-to-idle cycle, which is reported to significantly reduce power drawn by some systems when suspended to idle (by allowing them to reach a deep platform-wide low-power state through the suspend-to-idle flow). [What appears to happen is that the "noirq" resume of devices after a spurious EC wakeup brings some devices into a state in which they prevent the platform from reaching the deep low-power state going forward, even after a subsequent "noirq" suspend phase, and on some systems the EC triggers such wakeups already when the "noirq" suspend of devices is running for the first time in the given suspend/resume cycle, so the platform cannot reach the deep low-power state at all.] First, make acpi_s2idle_wake() use the acpi_ec_dispatch_gpe() return value to determine whether or not the wakeup may have been triggered by the EC (in which case the system wakeup is canceled and ACPI events are processed in order to determine whether or not the event is a proper system wakeup one) and use rearm_wake_irq() (introduced by a previous change) in it to rearm the ACPI SCI for system wakeup detection in case the system will remain suspended. Second, drop acpi_s2idle_sync(), which is not needed any more, and the corresponding global platform suspend-to-idle callback. Next, drop the pm_wakeup_pending() check (which is an optimization only) from __device_suspend_noirq() to prevent it from returning errors on system wakeups occurring before the "noirq" phase of device suspend is complete (as in the case of suspend-to-idle it is not known whether or not these wakeups are suprious at that point), in order to avoid having to carry out a "noirq" resume of devices on a spurious system wakeup. Finally, change the code flow in s2idle_loop() to (1) run the "noirq" suspend of devices once before starting the loop, (2) check for spurious EC wakeups (via the platform ->wake callback) for the first time before calling s2idle_enter(), and (3) run the "noirq" resume of devices once after leaving the loop. Signed-off-by: Rafael J. Wysocki Acked-by: Thomas Gleixner

Merge branch 'pm-sleep'

2019-07-08T08:51:25Z

* pm-sleep: PM: sleep: Drop dev_pm_skip_next_resume_phases() ACPI: PM: Drop unused function and function header ACPI: PM: Introduce "poweroff" callbacks for ACPI PM domain and LPSS ACPI: PM: Simplify and fix PM domain hibernation callbacks PCI: PM: Simplify bus-level hibernation callbacks PM: ACPI/PCI: Resume all devices during hibernation kernel: power: swap: use kzalloc() instead of kmalloc() followed by memset() PM: sleep: Update struct wakeup_source documentation drivers: base: power: remove wakeup_sources_stats_dentry variable PM: suspend: Rename pm_suspend_via_s2idle() PM: sleep: Show how long dpm_suspend_start() and dpm_suspend_end() take PM: hibernate: powerpc: Expose pfn_is_nosave() prototype

PCI: PM: Avoid skipping bus-level PM on platforms without ACPI

2019-06-26T21:51:56Z

There are platforms that do not call pm_set_suspend_via_firmware(), so pm_suspend_via_firmware() returns 'false' on them, but the power states of PCI devices (PCIe ports in particular) are changed as a result of powering down core platform components during system-wide suspend. Thus the pm_suspend_via_firmware() checks in pci_pm_suspend_noirq() and pci_pm_resume_noirq() introduced by commit 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to- idle") are not sufficient to determine that devices left in D0 during suspend will remain in D0 during resume and so the bus-level power management can be skipped for them. For this reason, introduce a new global suspend flag, PM_SUSPEND_FLAG_NO_PLATFORM, set it for suspend-to-idle only and replace the pm_suspend_via_firmware() checks mentioned above with checks against this flag. Fixes: 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to-idle") Reported-by: Jon Hunter Tested-by: Jon Hunter Signed-off-by: Rafael J. Wysocki Tested-by: Mika Westerberg Reviewed-by: Mika Westerberg

PM: suspend: Rename pm_suspend_via_s2idle()

2019-06-19T09:41:26Z

The name of pm_suspend_via_s2idle() is confusing, as it doesn't reflect the purpose of the function precisely enough and it is very similar to pm_suspend_via_firmware(), which has a different purpose, so rename it as pm_suspend_default_s2idle() and update its only caller, i8042_register_ports(), accordingly. Signed-off-by: Rafael J. Wysocki Acked-by: Dmitry Torokhov