kernel/linux.git/drivers/base/power/main.c, branch v5.9.12

PM: sleep: core: Fix the handling of pending runtime resume requests

2020-08-25T14:28:23+00:00

It has been reported that system-wide suspend may be aborted in the absence of any wakeup events due to unforseen interactions of it with the runtume PM framework. One failing scenario is when there are multiple devices sharing an ACPI power resource and runtime-resume needs to be carried out for one of them during system-wide suspend (for example, because it needs to be reconfigured before the whole system goes to sleep). In that case, the runtime-resume of that device involves turning the ACPI power resource "on" which in turn causes runtime-resume requests to be queued up for all of the other devices sharing it. Those requests go to the runtime PM workqueue which is frozen during system-wide suspend, so they are not actually taken care of until the resume of the whole system, but the pm_runtime_barrier() call in __device_suspend() sees them and triggers system wakeup events for them which then cause the system-wide suspend to be aborted if wakeup source objects are in active use. Of course, the logic that leads to triggering those wakeup events is questionable in the first place, because clearly there are cases in which a pending runtime resume request for a device is not connected to any real wakeup events in any way (like the one above). Moreover, it is racy, because the device may be resuming already by the time the pm_runtime_barrier() runs and so if the driver doesn't take care of signaling the wakeup event as appropriate, it will be lost. However, if the driver does take care of that, the extra pm_wakeup_event() call in the core is redundant. Accordingly, drop the conditional pm_wakeup_event() call fron __device_suspend() and make the latter call pm_runtime_barrier() alone. Also modify the comment next to that call to reflect the new code and extend it to mention the need to avoid unwanted interactions between runtime PM and system-wide device suspend callbacks. Fixes: 1e2ef05bb8cf8 ("PM: Limit race conditions between runtime PM and system sleep (v2)") Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Reported-by: Utkarsh H Patel Tested-by: Utkarsh H Patel Tested-by: Pengfei Xu Cc: All applicable

kernel: rename show_stack_loglvl() => show_stack()

2020-06-09T16:39:13+00:00

Now the last users of show_stack() got converted to use an explicit log level, show_stack_loglvl() can drop it's redundant suffix and become once again well known show_stack(). Signed-off-by: Dmitry Safonov Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com Signed-off-by: Linus Torvalds

power: use show_stack_loglvl()

2020-06-09T16:39:12+00:00

Aligning with other watchdog messages just before panic - use KERN_EMERG. Signed-off-by: Dmitry Safonov Signed-off-by: Andrew Morton Acked-by: Rafael J. Wysocki Cc: Greg Kroah-Hartman Cc: Len Brown Cc: Pavel Machek Link: http://lkml.kernel.org/r/20200418201944.482088-47-dima@arista.com Signed-off-by: Linus Torvalds

Merge back system-wide PM updates for v5.8.

2020-04-24T19:37:01+00:00

PM: sleep: core: Rename DPM_FLAG_LEAVE_SUSPENDED

2020-04-24T19:34:22+00:00

Rename DPM_FLAG_LEAVE_SUSPENDED to DPM_FLAG_MAY_SKIP_RESUME which matches its purpose more closely. No functional impact. Suggested-by: Alan Stern Signed-off-by: Rafael J. Wysocki Acked-by: Wolfram Sang # for I2C Acked-by: Alan Stern Acked-by: Bjorn Helgaas

PM: sleep: core: Rename DPM_FLAG_NEVER_SKIP

2020-04-24T19:33:09+00:00

Rename DPM_FLAG_NEVER_SKIP to DPM_FLAG_NO_DIRECT_COMPLETE which matches its purpose more closely. No functional impact. Suggested-by: Alan Stern Signed-off-by: Rafael J. Wysocki Acked-by: Bjorn Helgaas # for PCI parts Acked-by: Jeff Kirsher Acked-by: Alan Stern Acked-by: Bjorn Helgaas Acked-by: Alex Deucher

PM: sleep: core: Rename dev_pm_smart_suspend_and_suspended()

2020-04-24T19:32:41+00:00

Because all callers of dev_pm_smart_suspend_and_suspended use it only for checking whether or not to skip driver suspend callbacks for a device, rename it to dev_pm_skip_suspend() in analogy with dev_pm_skip_resume(). No functional impact. Suggested-by: Alan Stern Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Acked-by: Bjorn Helgaas

PM: sleep: core: Rename dev_pm_may_skip_resume()

2020-04-24T19:32:11+00:00

The name of dev_pm_may_skip_resume() may be easily confused with the power.may_skip_resume flag which is not checked by that function, so rename the former as dev_pm_skip_resume(). No functional impact. Suggested-by: Alan Stern Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Acked-by: Bjorn Helgaas

PM: sleep: core: Rework the power.may_skip_resume handling

2020-04-24T19:31:28+00:00

Because the power.may_skip_resume device status bit is taken into account in combination with the DPM_FLAG_LEAVE_SUSPENDED driver flag, it can be set to 'true' for all devices in the "suspend" phase of a suspend-resume cycle, so do that. Then, neither the PM core nor the middle-layer (sybsystem) code handling it needs to set it to 'true' any more and it just has to be cleared if there is a reason to avoid skipping the "noirq" and "early" resume callbacks provided by the driver, so update the code in question accordingly. Suggested-by: Alan Stern Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Acked-by: Bjorn Helgaas

PM: sleep: core: Do not skip callbacks in the resume phase

2020-04-24T19:31:14+00:00

The current code in device_resume_noirq() causes the entire early resume and resume phases of device suspend to be skipped for devices for which the noirq resume phase have been skipped (due to the LEAVE_SUSPENDED flag being set) on the premise that those devices should stay in runtime-suspend after system-wide resume. However, that may not be correct in two situations. First, the middle layer (subsystem) noirq resume callback may be missing for a given device, but its early resume callback may be present and it may need to do something even if it decides to skip the driver callback. Second, if the device's wakeup settings were adjusted in the suspend phase without resuming the device (that was in runtime suspend at that time), they most likely need to be adjusted again in the resume phase and so the driver callback in that phase needs to be run. For the above reason, modify the core to allow the middle layer ->resume_late callback to run even if its ->resume_noirq callback is missing (and the core has skipped the driver-level callback in that phase) and to allow all device callbacks to run in the resume phase. Also make the core set the PM-runtime status of devices with SMART_SUSPEND set whose resume callbacks are not skipped to "active" in the "noirq" resume phase and update the affected subsystems (PCI and ACPI) accordingly. After this change, middle-layer (subsystem) callbacks will always be invoked in all phases of system suspend and resume and driver callbacks will always run in the prepare, suspend, resume, and complete phases for all devices. For devices with SMART_SUSPEND set, driver callbacks will be skipped in the late and noirq phases of system suspend if those devices remain in runtime suspend in __device_suspend_late(). Driver callbacks will also be skipped for them during the noirq and early phases of the "thaw" transition related to hibernation in that case. Setting LEAVE_SUSPENDED means that the driver allows its callbacks to be skipped in the noirq and early phases of system resume, but some additional conditions need to be met for that to happen (among other things, the power.may_skip_resume flag needs to be set for the device during system suspend for the driver callbacks to be skipped during the subsequent resume transition). For all devices with SMART_SUSPEND set whose driver callbacks are invoked during system resume, the PM-runtime status will be set to "active" (by the core). Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern Acked-by: Bjorn Helgaas