![Rafael J. Wysocki](/assets/img/avatar_default.png)
One of the arguments during the suspend blockers discussion was that the mainline kernel didn't contain any mechanisms making it possible to avoid races between wakeup and system suspend. Generally, there are two problems in that area. First, if a wakeup event occurs exactly when /sys/power/state is being written to, it may be delivered to user space right before the freezer kicks in, so the user space consumer of the event may not be able to process it before the system is suspended. Second, if a wakeup event occurs after user space has been frozen, it is not generally guaranteed that the ongoing transition of the system into a sleep state will be aborted. To address these issues introduce a new global sysfs attribute, /sys/power/wakeup_count, associated with a running counter of wakeup events and three helper functions, pm_stay_awake(), pm_relax(), and pm_wakeup_event(), that may be used by kernel subsystems to control the behavior of this attribute and to request the PM core to abort system transitions into a sleep state already in progress. The /sys/power/wakeup_count file may be read from or written to by user space. Reads will always succeed (unless interrupted by a signal) and return the current value of the wakeup events counter. Writes, however, will only succeed if the written number is equal to the current value of the wakeup events counter. If a write is successful, it will cause the kernel to save the current value of the wakeup events counter and to abort the subsequent system transition into a sleep state if any wakeup events are reported after the write has returned. [The assumption is that before writing to /sys/power/state user space will first read from /sys/power/wakeup_count. Next, user space consumers of wakeup events will have a chance to acknowledge or veto the upcoming system transition to a sleep state. Finally, if the transition is allowed to proceed, /sys/power/wakeup_count will be written to and if that succeeds, /sys/power/state will be written to as well. Still, if any wakeup events are reported to the PM core by kernel subsystems after that point, the transition will be aborted.] Additionally, put a wakeup events counter into struct dev_pm_info and make these per-device wakeup event counters available via sysfs, so that it's possible to check the activity of various wakeup event sources within the kernel. To illustrate how subsystems can use pm_wakeup_event(), make the low-level PCI runtime PM wakeup-handling code use it. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-by: markgross <markgross@thegnar.org> Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
340 lines
12 KiB
C
340 lines
12 KiB
C
#ifndef _LINUX_SUSPEND_H
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#define _LINUX_SUSPEND_H
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#include <linux/swap.h>
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#include <linux/notifier.h>
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#include <linux/init.h>
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#include <linux/pm.h>
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#include <linux/mm.h>
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#include <asm/errno.h>
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#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
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extern void pm_set_vt_switch(int);
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extern int pm_prepare_console(void);
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extern void pm_restore_console(void);
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#else
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static inline void pm_set_vt_switch(int do_switch)
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{
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}
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static inline int pm_prepare_console(void)
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{
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return 0;
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}
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static inline void pm_restore_console(void)
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{
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}
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#endif
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typedef int __bitwise suspend_state_t;
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#define PM_SUSPEND_ON ((__force suspend_state_t) 0)
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#define PM_SUSPEND_STANDBY ((__force suspend_state_t) 1)
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#define PM_SUSPEND_MEM ((__force suspend_state_t) 3)
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#define PM_SUSPEND_MAX ((__force suspend_state_t) 4)
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/**
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* struct platform_suspend_ops - Callbacks for managing platform dependent
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* system sleep states.
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*
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* @valid: Callback to determine if given system sleep state is supported by
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* the platform.
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* Valid (ie. supported) states are advertised in /sys/power/state. Note
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* that it still may be impossible to enter given system sleep state if the
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* conditions aren't right.
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* There is the %suspend_valid_only_mem function available that can be
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* assigned to this if the platform only supports mem sleep.
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*
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* @begin: Initialise a transition to given system sleep state.
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* @begin() is executed right prior to suspending devices. The information
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* conveyed to the platform code by @begin() should be disregarded by it as
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* soon as @end() is executed. If @begin() fails (ie. returns nonzero),
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* @prepare(), @enter() and @finish() will not be called by the PM core.
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* This callback is optional. However, if it is implemented, the argument
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* passed to @enter() is redundant and should be ignored.
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*
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* @prepare: Prepare the platform for entering the system sleep state indicated
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* by @begin().
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* @prepare() is called right after devices have been suspended (ie. the
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* appropriate .suspend() method has been executed for each device) and
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* before device drivers' late suspend callbacks are executed. It returns
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* 0 on success or a negative error code otherwise, in which case the
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* system cannot enter the desired sleep state (@prepare_late(), @enter(),
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* @wake(), and @finish() will not be called in that case).
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*
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* @prepare_late: Finish preparing the platform for entering the system sleep
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* state indicated by @begin().
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* @prepare_late is called before disabling nonboot CPUs and after
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* device drivers' late suspend callbacks have been executed. It returns
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* 0 on success or a negative error code otherwise, in which case the
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* system cannot enter the desired sleep state (@enter() and @wake()).
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*
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* @enter: Enter the system sleep state indicated by @begin() or represented by
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* the argument if @begin() is not implemented.
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* This callback is mandatory. It returns 0 on success or a negative
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* error code otherwise, in which case the system cannot enter the desired
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* sleep state.
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*
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* @wake: Called when the system has just left a sleep state, right after
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* the nonboot CPUs have been enabled and before device drivers' early
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* resume callbacks are executed.
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* This callback is optional, but should be implemented by the platforms
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* that implement @prepare_late(). If implemented, it is always called
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* after @enter(), even if @enter() fails.
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*
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* @finish: Finish wake-up of the platform.
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* @finish is called right prior to calling device drivers' regular suspend
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* callbacks.
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* This callback is optional, but should be implemented by the platforms
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* that implement @prepare(). If implemented, it is always called after
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* @enter() and @wake(), if implemented, even if any of them fails.
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*
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* @end: Called by the PM core right after resuming devices, to indicate to
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* the platform that the system has returned to the working state or
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* the transition to the sleep state has been aborted.
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* This callback is optional, but should be implemented by the platforms
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* that implement @begin(). Accordingly, platforms implementing @begin()
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* should also provide a @end() which cleans up transitions aborted before
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* @enter().
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*
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* @recover: Recover the platform from a suspend failure.
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* Called by the PM core if the suspending of devices fails.
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* This callback is optional and should only be implemented by platforms
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* which require special recovery actions in that situation.
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*/
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struct platform_suspend_ops {
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int (*valid)(suspend_state_t state);
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int (*begin)(suspend_state_t state);
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int (*prepare)(void);
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int (*prepare_late)(void);
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int (*enter)(suspend_state_t state);
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void (*wake)(void);
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void (*finish)(void);
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void (*end)(void);
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void (*recover)(void);
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};
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#ifdef CONFIG_SUSPEND
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/**
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* suspend_set_ops - set platform dependent suspend operations
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* @ops: The new suspend operations to set.
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*/
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extern void suspend_set_ops(struct platform_suspend_ops *ops);
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extern int suspend_valid_only_mem(suspend_state_t state);
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/**
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* arch_suspend_disable_irqs - disable IRQs for suspend
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*
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* Disables IRQs (in the default case). This is a weak symbol in the common
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* code and thus allows architectures to override it if more needs to be
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* done. Not called for suspend to disk.
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*/
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extern void arch_suspend_disable_irqs(void);
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/**
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* arch_suspend_enable_irqs - enable IRQs after suspend
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*
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* Enables IRQs (in the default case). This is a weak symbol in the common
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* code and thus allows architectures to override it if more needs to be
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* done. Not called for suspend to disk.
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*/
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extern void arch_suspend_enable_irqs(void);
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extern int pm_suspend(suspend_state_t state);
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#else /* !CONFIG_SUSPEND */
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#define suspend_valid_only_mem NULL
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static inline void suspend_set_ops(struct platform_suspend_ops *ops) {}
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static inline int pm_suspend(suspend_state_t state) { return -ENOSYS; }
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#endif /* !CONFIG_SUSPEND */
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/* struct pbe is used for creating lists of pages that should be restored
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* atomically during the resume from disk, because the page frames they have
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* occupied before the suspend are in use.
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*/
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struct pbe {
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void *address; /* address of the copy */
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void *orig_address; /* original address of a page */
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struct pbe *next;
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};
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/* mm/page_alloc.c */
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extern void mark_free_pages(struct zone *zone);
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/**
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* struct platform_hibernation_ops - hibernation platform support
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*
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* The methods in this structure allow a platform to carry out special
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* operations required by it during a hibernation transition.
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*
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* All the methods below, except for @recover(), must be implemented.
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*
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* @begin: Tell the platform driver that we're starting hibernation.
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* Called right after shrinking memory and before freezing devices.
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*
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* @end: Called by the PM core right after resuming devices, to indicate to
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* the platform that the system has returned to the working state.
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*
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* @pre_snapshot: Prepare the platform for creating the hibernation image.
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* Called right after devices have been frozen and before the nonboot
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* CPUs are disabled (runs with IRQs on).
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*
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* @finish: Restore the previous state of the platform after the hibernation
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* image has been created *or* put the platform into the normal operation
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* mode after the hibernation (the same method is executed in both cases).
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* Called right after the nonboot CPUs have been enabled and before
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* thawing devices (runs with IRQs on).
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*
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* @prepare: Prepare the platform for entering the low power state.
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* Called right after the hibernation image has been saved and before
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* devices are prepared for entering the low power state.
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*
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* @enter: Put the system into the low power state after the hibernation image
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* has been saved to disk.
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* Called after the nonboot CPUs have been disabled and all of the low
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* level devices have been shut down (runs with IRQs off).
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*
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* @leave: Perform the first stage of the cleanup after the system sleep state
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* indicated by @set_target() has been left.
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* Called right after the control has been passed from the boot kernel to
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* the image kernel, before the nonboot CPUs are enabled and before devices
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* are resumed. Executed with interrupts disabled.
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*
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* @pre_restore: Prepare system for the restoration from a hibernation image.
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* Called right after devices have been frozen and before the nonboot
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* CPUs are disabled (runs with IRQs on).
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*
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* @restore_cleanup: Clean up after a failing image restoration.
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* Called right after the nonboot CPUs have been enabled and before
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* thawing devices (runs with IRQs on).
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*
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* @recover: Recover the platform from a failure to suspend devices.
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* Called by the PM core if the suspending of devices during hibernation
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* fails. This callback is optional and should only be implemented by
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* platforms which require special recovery actions in that situation.
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*/
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struct platform_hibernation_ops {
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int (*begin)(void);
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void (*end)(void);
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int (*pre_snapshot)(void);
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void (*finish)(void);
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int (*prepare)(void);
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int (*enter)(void);
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void (*leave)(void);
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int (*pre_restore)(void);
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void (*restore_cleanup)(void);
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void (*recover)(void);
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};
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#ifdef CONFIG_HIBERNATION
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/* kernel/power/snapshot.c */
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extern void __register_nosave_region(unsigned long b, unsigned long e, int km);
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static inline void __init register_nosave_region(unsigned long b, unsigned long e)
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{
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__register_nosave_region(b, e, 0);
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}
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static inline void __init register_nosave_region_late(unsigned long b, unsigned long e)
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{
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__register_nosave_region(b, e, 1);
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}
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extern int swsusp_page_is_forbidden(struct page *);
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extern void swsusp_set_page_free(struct page *);
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extern void swsusp_unset_page_free(struct page *);
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extern unsigned long get_safe_page(gfp_t gfp_mask);
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extern void hibernation_set_ops(struct platform_hibernation_ops *ops);
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extern int hibernate(void);
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extern bool system_entering_hibernation(void);
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#else /* CONFIG_HIBERNATION */
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static inline int swsusp_page_is_forbidden(struct page *p) { return 0; }
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static inline void swsusp_set_page_free(struct page *p) {}
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static inline void swsusp_unset_page_free(struct page *p) {}
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static inline void hibernation_set_ops(struct platform_hibernation_ops *ops) {}
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static inline int hibernate(void) { return -ENOSYS; }
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static inline bool system_entering_hibernation(void) { return false; }
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#endif /* CONFIG_HIBERNATION */
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#ifdef CONFIG_SUSPEND_NVS
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extern int suspend_nvs_register(unsigned long start, unsigned long size);
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extern int suspend_nvs_alloc(void);
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extern void suspend_nvs_free(void);
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extern void suspend_nvs_save(void);
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extern void suspend_nvs_restore(void);
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#else /* CONFIG_SUSPEND_NVS */
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static inline int suspend_nvs_register(unsigned long a, unsigned long b)
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{
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return 0;
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}
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static inline int suspend_nvs_alloc(void) { return 0; }
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static inline void suspend_nvs_free(void) {}
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static inline void suspend_nvs_save(void) {}
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static inline void suspend_nvs_restore(void) {}
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#endif /* CONFIG_SUSPEND_NVS */
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#ifdef CONFIG_PM_SLEEP
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void save_processor_state(void);
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void restore_processor_state(void);
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/* kernel/power/main.c */
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extern int register_pm_notifier(struct notifier_block *nb);
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extern int unregister_pm_notifier(struct notifier_block *nb);
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#define pm_notifier(fn, pri) { \
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static struct notifier_block fn##_nb = \
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{ .notifier_call = fn, .priority = pri }; \
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register_pm_notifier(&fn##_nb); \
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}
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/* drivers/base/power/wakeup.c */
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extern bool events_check_enabled;
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extern bool pm_check_wakeup_events(void);
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extern bool pm_get_wakeup_count(unsigned long *count);
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extern bool pm_save_wakeup_count(unsigned long count);
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#else /* !CONFIG_PM_SLEEP */
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static inline int register_pm_notifier(struct notifier_block *nb)
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{
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return 0;
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}
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static inline int unregister_pm_notifier(struct notifier_block *nb)
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{
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return 0;
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}
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#define pm_notifier(fn, pri) do { (void)(fn); } while (0)
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#endif /* !CONFIG_PM_SLEEP */
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extern struct mutex pm_mutex;
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#ifndef CONFIG_HIBERNATION
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static inline void register_nosave_region(unsigned long b, unsigned long e)
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{
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}
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static inline void register_nosave_region_late(unsigned long b, unsigned long e)
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{
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}
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static inline void lock_system_sleep(void) {}
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static inline void unlock_system_sleep(void) {}
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#else
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/* Let some subsystems like memory hotadd exclude hibernation */
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static inline void lock_system_sleep(void)
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{
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mutex_lock(&pm_mutex);
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}
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static inline void unlock_system_sleep(void)
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{
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mutex_unlock(&pm_mutex);
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}
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#endif
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#endif /* _LINUX_SUSPEND_H */
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