OSCL-LXR linux-6.0.1/​kernel/​power/​hibernate.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
  *
  * Copyright (c) 2003 Patrick Mochel
  * Copyright (c) 2003 Open Source Development Lab
  * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
  * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
  * Copyright (C) 2012 Bojan Smojver <bojan@rexursive.com>
  */
 
 #define pr_fmt(fmt) "PM: hibernation: " fmt
 
 #include <linux/export.h>
 #include <linux/suspend.h>
 #include <linux/reboot.h>
 #include <linux/string.h>
 #include <linux/device.h>
 #include <linux/async.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/pm.h>
 #include <linux/nmi.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
 #include <linux/gfp.h>
 #include <linux/syscore_ops.h>
 #include <linux/ctype.h>
 #include <linux/ktime.h>
 #include <linux/security.h>
 #include <linux/secretmem.h>
 #include <trace/events/power.h>
 
 #include "power.h"
 
 
 static int nocompress;
 static int noresume;
 static int nohibernate;
 static int resume_wait;
 static unsigned int resume_delay;
 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
 dev_t swsusp_resume_device;
 sector_t swsusp_resume_block;
 __visible int in_suspend __nosavedata;
 
 enum {
     HIBERNATION_INVALID,
     HIBERNATION_PLATFORM,
     HIBERNATION_SHUTDOWN,
     HIBERNATION_REBOOT,
 #ifdef CONFIG_SUSPEND
     HIBERNATION_SUSPEND,
 #endif
     HIBERNATION_TEST_RESUME,
     /* keep last */
     __HIBERNATION_AFTER_LAST
 };
 #define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
 #define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)
 
 static int hibernation_mode = HIBERNATION_SHUTDOWN;
 
 bool freezer_test_done;
 
 static const struct platform_hibernation_ops *hibernation_ops;
 
 static atomic_t hibernate_atomic = ATOMIC_INIT(1);
 
 bool hibernate_acquire(void)
 {
     return atomic_add_unless(&hibernate_atomic, -1, 0);
 }
 
 void hibernate_release(void)
 {
     atomic_inc(&hibernate_atomic);
 }
 
 bool hibernation_available(void)
 {
     return nohibernate == 0 &&
         !security_locked_down(LOCKDOWN_HIBERNATION) &&
         !secretmem_active() && !cxl_mem_active();
 }
 
 /**
  * hibernation_set_ops - Set the global hibernate operations.
  * @ops: Hibernation operations to use in subsequent hibernation transitions.
  */
 void hibernation_set_ops(const struct platform_hibernation_ops *ops)
 {
     if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
         && ops->prepare && ops->finish && ops->enter && ops->pre_restore
         && ops->restore_cleanup && ops->leave)) {
         WARN_ON(1);
         return;
     }
     lock_system_sleep();
     hibernation_ops = ops;
     if (ops)
         hibernation_mode = HIBERNATION_PLATFORM;
     else if (hibernation_mode == HIBERNATION_PLATFORM)
         hibernation_mode = HIBERNATION_SHUTDOWN;
 
     unlock_system_sleep();
 }
 EXPORT_SYMBOL_GPL(hibernation_set_ops);
 
 static bool entering_platform_hibernation;
 
 bool system_entering_hibernation(void)
 {
     return entering_platform_hibernation;
 }
 EXPORT_SYMBOL(system_entering_hibernation);
 
 #ifdef CONFIG_PM_DEBUG
 static void hibernation_debug_sleep(void)
 {
     pr_info("debug: Waiting for 5 seconds.\n");
     mdelay(5000);
 }
 
 static int hibernation_test(int level)
 {
     if (pm_test_level == level) {
         hibernation_debug_sleep();
         return 1;
     }
     return 0;
 }
 #else /* !CONFIG_PM_DEBUG */
 static int hibernation_test(int level) { return 0; }
 #endif /* !CONFIG_PM_DEBUG */
 
 /**
  * platform_begin - Call platform to start hibernation.
  * @platform_mode: Whether or not to use the platform driver.
  */
 static int platform_begin(int platform_mode)
 {
     return (platform_mode && hibernation_ops) ?
         hibernation_ops->begin(PMSG_FREEZE) : 0;
 }
 
 /**
  * platform_end - Call platform to finish transition to the working state.
  * @platform_mode: Whether or not to use the platform driver.
  */
 static void platform_end(int platform_mode)
 {
     if (platform_mode && hibernation_ops)
         hibernation_ops->end();
 }
 
 /**
  * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Use the platform driver to prepare the system for creating a hibernate image,
  * if so configured, and return an error code if that fails.
  */
 
 static int platform_pre_snapshot(int platform_mode)
 {
     return (platform_mode && hibernation_ops) ?
         hibernation_ops->pre_snapshot() : 0;
 }
 
 /**
  * platform_leave - Call platform to prepare a transition to the working state.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Use the platform driver prepare to prepare the machine for switching to the
  * normal mode of operation.
  *
  * This routine is called on one CPU with interrupts disabled.
  */
 static void platform_leave(int platform_mode)
 {
     if (platform_mode && hibernation_ops)
         hibernation_ops->leave();
 }
 
 /**
  * platform_finish - Call platform to switch the system to the working state.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Use the platform driver to switch the machine to the normal mode of
  * operation.
  *
  * This routine must be called after platform_prepare().
  */
 static void platform_finish(int platform_mode)
 {
     if (platform_mode && hibernation_ops)
         hibernation_ops->finish();
 }
 
 /**
  * platform_pre_restore - Prepare for hibernate image restoration.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Use the platform driver to prepare the system for resume from a hibernation
  * image.
  *
  * If the restore fails after this function has been called,
  * platform_restore_cleanup() must be called.
  */
 static int platform_pre_restore(int platform_mode)
 {
     return (platform_mode && hibernation_ops) ?
         hibernation_ops->pre_restore() : 0;
 }
 
 /**
  * platform_restore_cleanup - Switch to the working state after failing restore.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Use the platform driver to switch the system to the normal mode of operation
  * after a failing restore.
  *
  * If platform_pre_restore() has been called before the failing restore, this
  * function must be called too, regardless of the result of
  * platform_pre_restore().
  */
 static void platform_restore_cleanup(int platform_mode)
 {
     if (platform_mode && hibernation_ops)
         hibernation_ops->restore_cleanup();
 }
 
 /**
  * platform_recover - Recover from a failure to suspend devices.
  * @platform_mode: Whether or not to use the platform driver.
  */
 static void platform_recover(int platform_mode)
 {
     if (platform_mode && hibernation_ops && hibernation_ops->recover)
         hibernation_ops->recover();
 }
 
 /**
  * swsusp_show_speed - Print time elapsed between two events during hibernation.
  * @start: Starting event.
  * @stop: Final event.
  * @nr_pages: Number of memory pages processed between @start and @stop.
  * @msg: Additional diagnostic message to print.
  */
 void swsusp_show_speed(ktime_t start, ktime_t stop,
               unsigned nr_pages, char *msg)
 {
     ktime_t diff;
     u64 elapsed_centisecs64;
     unsigned int centisecs;
     unsigned int k;
     unsigned int kps;
 
     diff = ktime_sub(stop, start);
     elapsed_centisecs64 = ktime_divns(diff, 10*NSEC_PER_MSEC);
     centisecs = elapsed_centisecs64;
     if (centisecs == 0)
         centisecs = 1;  /* avoid div-by-zero */
     k = nr_pages * (PAGE_SIZE / 1024);
     kps = (k * 100) / centisecs;
     pr_info("%s %u kbytes in %u.%02u seconds (%u.%02u MB/s)\n",
         msg, k, centisecs / 100, centisecs % 100, kps / 1000,
         (kps % 1000) / 10);
 }
 
 __weak int arch_resume_nosmt(void)
 {
     return 0;
 }
 
 /**
  * create_image - Create a hibernation image.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Execute device drivers' "late" and "noirq" freeze callbacks, create a
  * hibernation image and run the drivers' "noirq" and "early" thaw callbacks.
  *
  * Control reappears in this routine after the subsequent restore.
  */
 static int create_image(int platform_mode)
 {
     int error;
 
     error = dpm_suspend_end(PMSG_FREEZE);
     if (error) {
         pr_err("Some devices failed to power down, aborting\n");
         return error;
     }
 
     error = platform_pre_snapshot(platform_mode);
     if (error || hibernation_test(TEST_PLATFORM))
         goto Platform_finish;
 
     error = pm_sleep_disable_secondary_cpus();
     if (error || hibernation_test(TEST_CPUS))
         goto Enable_cpus;
 
     local_irq_disable();
 
     system_state = SYSTEM_SUSPEND;
 
     error = syscore_suspend();
     if (error) {
         pr_err("Some system devices failed to power down, aborting\n");
         goto Enable_irqs;
     }
 
     if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
         goto Power_up;
 
     in_suspend = 1;
     save_processor_state();
     trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
     error = swsusp_arch_suspend();
     /* Restore control flow magically appears here */
     restore_processor_state();
     trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
     if (error)
         pr_err("Error %d creating image\n", error);
 
     if (!in_suspend) {
         events_check_enabled = false;
         clear_or_poison_free_pages();
     }
 
     platform_leave(platform_mode);
 
  Power_up:
     syscore_resume();
 
  Enable_irqs:
     system_state = SYSTEM_RUNNING;
     local_irq_enable();
 
  Enable_cpus:
     pm_sleep_enable_secondary_cpus();
 
     /* Allow architectures to do nosmt-specific post-resume dances */
     if (!in_suspend)
         error = arch_resume_nosmt();
 
  Platform_finish:
     platform_finish(platform_mode);
 
     dpm_resume_start(in_suspend ?
         (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
 
     return error;
 }
 
 /**
  * hibernation_snapshot - Quiesce devices and create a hibernation image.
  * @platform_mode: If set, use platform driver to prepare for the transition.
  *
  * This routine must be called with system_transition_mutex held.
  */
 int hibernation_snapshot(int platform_mode)
 {
     pm_message_t msg;
     int error;
 
     pm_suspend_clear_flags();
     error = platform_begin(platform_mode);
     if (error)
         goto Close;
 
     /* Preallocate image memory before shutting down devices. */
     error = hibernate_preallocate_memory();
     if (error)
         goto Close;
 
     error = freeze_kernel_threads();
     if (error)
         goto Cleanup;
 
     if (hibernation_test(TEST_FREEZER)) {
 
         /*
          * Indicate to the caller that we are returning due to a
          * successful freezer test.
          */
         freezer_test_done = true;
         goto Thaw;
     }
 
     error = dpm_prepare(PMSG_FREEZE);
     if (error) {
         dpm_complete(PMSG_RECOVER);
         goto Thaw;
     }
 
     suspend_console();
     pm_restrict_gfp_mask();
 
     error = dpm_suspend(PMSG_FREEZE);
 
     if (error || hibernation_test(TEST_DEVICES))
         platform_recover(platform_mode);
     else
         error = create_image(platform_mode);
 
     /*
      * In the case that we call create_image() above, the control
      * returns here (1) after the image has been created or the
      * image creation has failed and (2) after a successful restore.
      */
 
     /* We may need to release the preallocated image pages here. */
     if (error || !in_suspend)
         swsusp_free();
 
     msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
     dpm_resume(msg);
 
     if (error || !in_suspend)
         pm_restore_gfp_mask();
 
     resume_console();
     dpm_complete(msg);
 
  Close:
     platform_end(platform_mode);
     return error;
 
  Thaw:
     thaw_kernel_threads();
  Cleanup:
     swsusp_free();
     goto Close;
 }
 
 int __weak hibernate_resume_nonboot_cpu_disable(void)
 {
     return suspend_disable_secondary_cpus();
 }
 
 /**
  * resume_target_kernel - Restore system state from a hibernation image.
  * @platform_mode: Whether or not to use the platform driver.
  *
  * Execute device drivers' "noirq" and "late" freeze callbacks, restore the
  * contents of highmem that have not been restored yet from the image and run
  * the low-level code that will restore the remaining contents of memory and
  * switch to the just restored target kernel.
  */
 static int resume_target_kernel(bool platform_mode)
 {
     int error;
 
     error = dpm_suspend_end(PMSG_QUIESCE);
     if (error) {
         pr_err("Some devices failed to power down, aborting resume\n");
         return error;
     }
 
     error = platform_pre_restore(platform_mode);
     if (error)
         goto Cleanup;
 
     cpuidle_pause();
 
     error = hibernate_resume_nonboot_cpu_disable();
     if (error)
         goto Enable_cpus;
 
     local_irq_disable();
     system_state = SYSTEM_SUSPEND;
 
     error = syscore_suspend();
     if (error)
         goto Enable_irqs;
 
     save_processor_state();
     error = restore_highmem();
     if (!error) {
         error = swsusp_arch_resume();
         /*
          * The code below is only ever reached in case of a failure.
          * Otherwise, execution continues at the place where
          * swsusp_arch_suspend() was called.
          */
         BUG_ON(!error);
         /*
          * This call to restore_highmem() reverts the changes made by
          * the previous one.
          */
         restore_highmem();
     }
     /*
      * The only reason why swsusp_arch_resume() can fail is memory being
      * very tight, so we have to free it as soon as we can to avoid
      * subsequent failures.
      */
     swsusp_free();
     restore_processor_state();
     touch_softlockup_watchdog();
 
     syscore_resume();
 
  Enable_irqs:
     system_state = SYSTEM_RUNNING;
     local_irq_enable();
 
  Enable_cpus:
     pm_sleep_enable_secondary_cpus();
 
  Cleanup:
     platform_restore_cleanup(platform_mode);
 
     dpm_resume_start(PMSG_RECOVER);
 
     return error;
 }
 
 /**
  * hibernation_restore - Quiesce devices and restore from a hibernation image.
  * @platform_mode: If set, use platform driver to prepare for the transition.
  *
  * This routine must be called with system_transition_mutex held.  If it is
  * successful, control reappears in the restored target kernel in
  * hibernation_snapshot().
  */
 int hibernation_restore(int platform_mode)
 {
     int error;
 
     pm_prepare_console();
     suspend_console();
     pm_restrict_gfp_mask();
     error = dpm_suspend_start(PMSG_QUIESCE);
     if (!error) {
         error = resume_target_kernel(platform_mode);
         /*
          * The above should either succeed and jump to the new kernel,
          * or return with an error. Otherwise things are just
          * undefined, so let's be paranoid.
          */
         BUG_ON(!error);
     }
     dpm_resume_end(PMSG_RECOVER);
     pm_restore_gfp_mask();
     resume_console();
     pm_restore_console();
     return error;
 }
 
 /**
  * hibernation_platform_enter - Power off the system using the platform driver.
  */
 int hibernation_platform_enter(void)
 {
     int error;
 
     if (!hibernation_ops)
         return -ENOSYS;
 
     /*
      * We have cancelled the power transition by running
      * hibernation_ops->finish() before saving the image, so we should let
      * the firmware know that we're going to enter the sleep state after all
      */
     error = hibernation_ops->begin(PMSG_HIBERNATE);
     if (error)
         goto Close;
 
     entering_platform_hibernation = true;
     suspend_console();
     error = dpm_suspend_start(PMSG_HIBERNATE);
     if (error) {
         if (hibernation_ops->recover)
             hibernation_ops->recover();
         goto Resume_devices;
     }
 
     error = dpm_suspend_end(PMSG_HIBERNATE);
     if (error)
         goto Resume_devices;
 
     error = hibernation_ops->prepare();
     if (error)
         goto Platform_finish;
 
     error = pm_sleep_disable_secondary_cpus();
     if (error)
         goto Enable_cpus;
 
     local_irq_disable();
     system_state = SYSTEM_SUSPEND;
     syscore_suspend();
     if (pm_wakeup_pending()) {
         error = -EAGAIN;
         goto Power_up;
     }
 
     hibernation_ops->enter();
     /* We should never get here */
     while (1);
 
  Power_up:
     syscore_resume();
     system_state = SYSTEM_RUNNING;
     local_irq_enable();
 
  Enable_cpus:
     pm_sleep_enable_secondary_cpus();
 
  Platform_finish:
     hibernation_ops->finish();
 
     dpm_resume_start(PMSG_RESTORE);
 
  Resume_devices:
     entering_platform_hibernation = false;
     dpm_resume_end(PMSG_RESTORE);
     resume_console();
 
  Close:
     hibernation_ops->end();
 
     return error;
 }
 
 /**
  * power_down - Shut the machine down for hibernation.
  *
  * Use the platform driver, if configured, to put the system into the sleep
  * state corresponding to hibernation, or try to power it off or reboot,
  * depending on the value of hibernation_mode.
  */
 static void power_down(void)
 {
 #ifdef CONFIG_SUSPEND
     int error;
 
     if (hibernation_mode == HIBERNATION_SUSPEND) {
         error = suspend_devices_and_enter(PM_SUSPEND_MEM);
         if (error) {
             hibernation_mode = hibernation_ops ?
                         HIBERNATION_PLATFORM :
                         HIBERNATION_SHUTDOWN;
         } else {
             /* Restore swap signature. */
             error = swsusp_unmark();
             if (error)
                 pr_err("Swap will be unusable! Try swapon -a.\n");
 
             return;
         }
     }
 #endif
 
     switch (hibernation_mode) {
     case HIBERNATION_REBOOT:
         kernel_restart(NULL);
         break;
     case HIBERNATION_PLATFORM:
         hibernation_platform_enter();
         fallthrough;
     case HIBERNATION_SHUTDOWN:
         if (kernel_can_power_off())
             kernel_power_off();
         break;
     }
     kernel_halt();
     /*
      * Valid image is on the disk, if we continue we risk serious data
      * corruption after resume.
      */
     pr_crit("Power down manually\n");
     while (1)
         cpu_relax();
 }
 
 static int load_image_and_restore(void)
 {
     int error;
     unsigned int flags;
 
     pm_pr_dbg("Loading hibernation image.\n");
 
     lock_device_hotplug();
     error = create_basic_memory_bitmaps();
     if (error) {
         swsusp_close(FMODE_READ | FMODE_EXCL);
         goto Unlock;
     }
 
     error = swsusp_read(&flags);
     swsusp_close(FMODE_READ | FMODE_EXCL);
     if (!error)
         error = hibernation_restore(flags & SF_PLATFORM_MODE);
 
     pr_err("Failed to load image, recovering.\n");
     swsusp_free();
     free_basic_memory_bitmaps();
  Unlock:
     unlock_device_hotplug();
 
     return error;
 }
 
 /**
  * hibernate - Carry out system hibernation, including saving the image.
  */
 int hibernate(void)
 {
     bool snapshot_test = false;
     int error;
 
     if (!hibernation_available()) {
         pm_pr_dbg("Hibernation not available.\n");
         return -EPERM;
     }
 
     lock_system_sleep();
     /* The snapshot device should not be opened while we're running */
     if (!hibernate_acquire()) {
         error = -EBUSY;
         goto Unlock;
     }
 
     pr_info("hibernation entry\n");
     pm_prepare_console();
     error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
     if (error)
         goto Restore;
 
     ksys_sync_helper();
 
     error = freeze_processes();
     if (error)
         goto Exit;
 
     lock_device_hotplug();
     /* Allocate memory management structures */
     error = create_basic_memory_bitmaps();
     if (error)
         goto Thaw;
 
     error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
     if (error || freezer_test_done)
         goto Free_bitmaps;
 
     if (in_suspend) {
         unsigned int flags = 0;
 
         if (hibernation_mode == HIBERNATION_PLATFORM)
             flags |= SF_PLATFORM_MODE;
         if (nocompress)
             flags |= SF_NOCOMPRESS_MODE;
         else
                 flags |= SF_CRC32_MODE;
 
         pm_pr_dbg("Writing hibernation image.\n");
         error = swsusp_write(flags);
         swsusp_free();
         if (!error) {
             if (hibernation_mode == HIBERNATION_TEST_RESUME)
                 snapshot_test = true;
             else
                 power_down();
         }
         in_suspend = 0;
         pm_restore_gfp_mask();
     } else {
         pm_pr_dbg("Hibernation image restored successfully.\n");
     }
 
  Free_bitmaps:
     free_basic_memory_bitmaps();
  Thaw:
     unlock_device_hotplug();
     if (snapshot_test) {
         pm_pr_dbg("Checking hibernation image\n");
         error = swsusp_check();
         if (!error)
             error = load_image_and_restore();
     }
     thaw_processes();
 
     /* Don't bother checking whether freezer_test_done is true */
     freezer_test_done = false;
  Exit:
     pm_notifier_call_chain(PM_POST_HIBERNATION);
  Restore:
     pm_restore_console();
     hibernate_release();
  Unlock:
     unlock_system_sleep();
     pr_info("hibernation exit\n");
 
     return error;
 }
 
 /**
  * hibernate_quiet_exec - Execute a function with all devices frozen.
  * @func: Function to execute.
  * @data: Data pointer to pass to @func.
  *
  * Return the @func return value or an error code if it cannot be executed.
  */
 int hibernate_quiet_exec(int (*func)(void *data), void *data)
 {
     int error;
 
     lock_system_sleep();
 
     if (!hibernate_acquire()) {
         error = -EBUSY;
         goto unlock;
     }
 
     pm_prepare_console();
 
     error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
     if (error)
         goto restore;
 
     error = freeze_processes();
     if (error)
         goto exit;
 
     lock_device_hotplug();
 
     pm_suspend_clear_flags();
 
     error = platform_begin(true);
     if (error)
         goto thaw;
 
     error = freeze_kernel_threads();
     if (error)
         goto thaw;
 
     error = dpm_prepare(PMSG_FREEZE);
     if (error)
         goto dpm_complete;
 
     suspend_console();
 
     error = dpm_suspend(PMSG_FREEZE);
     if (error)
         goto dpm_resume;
 
     error = dpm_suspend_end(PMSG_FREEZE);
     if (error)
         goto dpm_resume;
 
     error = platform_pre_snapshot(true);
     if (error)
         goto skip;
 
     error = func(data);
 
 skip:
     platform_finish(true);
 
     dpm_resume_start(PMSG_THAW);
 
 dpm_resume:
     dpm_resume(PMSG_THAW);
 
     resume_console();
 
 dpm_complete:
     dpm_complete(PMSG_THAW);
 
     thaw_kernel_threads();
 
 thaw:
     platform_end(true);
 
     unlock_device_hotplug();
 
     thaw_processes();
 
 exit:
     pm_notifier_call_chain(PM_POST_HIBERNATION);
 
 restore:
     pm_restore_console();
 
     hibernate_release();
 
 unlock:
     unlock_system_sleep();
 
     return error;
 }
 EXPORT_SYMBOL_GPL(hibernate_quiet_exec);
 
 /**
  * software_resume - Resume from a saved hibernation image.
  *
  * This routine is called as a late initcall, when all devices have been
  * discovered and initialized already.
  *
  * The image reading code is called to see if there is a hibernation image
  * available for reading.  If that is the case, devices are quiesced and the
  * contents of memory is restored from the saved image.
  *
  * If this is successful, control reappears in the restored target kernel in
  * hibernation_snapshot() which returns to hibernate().  Otherwise, the routine
  * attempts to recover gracefully and make the kernel return to the normal mode
  * of operation.
  */
 static int software_resume(void)
 {
     int error;
 
     /*
      * If the user said "noresume".. bail out early.
      */
     if (noresume || !hibernation_available())
         return 0;
 
     /*
      * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
      * is configured into the kernel. Since the regular hibernate
      * trigger path is via sysfs which takes a buffer mutex before
      * calling hibernate functions (which take system_transition_mutex)
      * this can cause lockdep to complain about a possible ABBA deadlock
      * which cannot happen since we're in the boot code here and
      * sysfs can't be invoked yet. Therefore, we use a subclass
      * here to avoid lockdep complaining.
      */
     mutex_lock_nested(&system_transition_mutex, SINGLE_DEPTH_NESTING);
 
     if (swsusp_resume_device)
         goto Check_image;
 
     if (!strlen(resume_file)) {
         error = -ENOENT;
         goto Unlock;
     }
 
     pm_pr_dbg("Checking hibernation image partition %s\n", resume_file);
 
     if (resume_delay) {
         pr_info("Waiting %dsec before reading resume device ...\n",
             resume_delay);
         ssleep(resume_delay);
     }
 
     /* Check if the device is there */
     swsusp_resume_device = name_to_dev_t(resume_file);
     if (!swsusp_resume_device) {
         /*
          * Some device discovery might still be in progress; we need
          * to wait for this to finish.
          */
         wait_for_device_probe();
 
         if (resume_wait) {
             while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
                 msleep(10);
             async_synchronize_full();
         }
 
         swsusp_resume_device = name_to_dev_t(resume_file);
         if (!swsusp_resume_device) {
             error = -ENODEV;
             goto Unlock;
         }
     }
 
  Check_image:
     pm_pr_dbg("Hibernation image partition %d:%d present\n",
         MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
 
     pm_pr_dbg("Looking for hibernation image.\n");
     error = swsusp_check();
     if (error)
         goto Unlock;
 
     /* The snapshot device should not be opened while we're running */
     if (!hibernate_acquire()) {
         error = -EBUSY;
         swsusp_close(FMODE_READ | FMODE_EXCL);
         goto Unlock;
     }
 
     pr_info("resume from hibernation\n");
     pm_prepare_console();
     error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
     if (error)
         goto Restore;
 
     pm_pr_dbg("Preparing processes for hibernation restore.\n");
     error = freeze_processes();
     if (error)
         goto Close_Finish;
 
     error = freeze_kernel_threads();
     if (error) {
         thaw_processes();
         goto Close_Finish;
     }
 
     error = load_image_and_restore();
     thaw_processes();
  Finish:
     pm_notifier_call_chain(PM_POST_RESTORE);
  Restore:
     pm_restore_console();
     pr_info("resume failed (%d)\n", error);
     hibernate_release();
     /* For success case, the suspend path will release the lock */
  Unlock:
     mutex_unlock(&system_transition_mutex);
     pm_pr_dbg("Hibernation image not present or could not be loaded.\n");
     return error;
  Close_Finish:
     swsusp_close(FMODE_READ | FMODE_EXCL);
     goto Finish;
 }
 
 late_initcall_sync(software_resume);
 
 
 static const char * const hibernation_modes[] = {
     [HIBERNATION_PLATFORM]  = "platform",
     [HIBERNATION_SHUTDOWN]  = "shutdown",
     [HIBERNATION_REBOOT]    = "reboot",
 #ifdef CONFIG_SUSPEND
     [HIBERNATION_SUSPEND]   = "suspend",
 #endif
     [HIBERNATION_TEST_RESUME]   = "test_resume",
 };
 
 /*
  * /sys/power/disk - Control hibernation mode.
  *
  * Hibernation can be handled in several ways.  There are a few different ways
  * to put the system into the sleep state: using the platform driver (e.g. ACPI
  * or other hibernation_ops), powering it off or rebooting it (for testing
  * mostly).
  *
  * The sysfs file /sys/power/disk provides an interface for selecting the
  * hibernation mode to use.  Reading from this file causes the available modes
  * to be printed.  There are 3 modes that can be supported:
  *
  *  'platform'
  *  'shutdown'
  *  'reboot'
  *
  * If a platform hibernation driver is in use, 'platform' will be supported
  * and will be used by default.  Otherwise, 'shutdown' will be used by default.
  * The selected option (i.e. the one corresponding to the current value of
  * hibernation_mode) is enclosed by a square bracket.
  *
  * To select a given hibernation mode it is necessary to write the mode's
  * string representation (as returned by reading from /sys/power/disk) back
  * into /sys/power/disk.
  */
 
 static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
              char *buf)
 {
     int i;
     char *start = buf;
 
     if (!hibernation_available())
         return sprintf(buf, "[disabled]\n");
 
     for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
         if (!hibernation_modes[i])
             continue;
         switch (i) {
         case HIBERNATION_SHUTDOWN:
         case HIBERNATION_REBOOT:
 #ifdef CONFIG_SUSPEND
         case HIBERNATION_SUSPEND:
 #endif
         case HIBERNATION_TEST_RESUME:
             break;
         case HIBERNATION_PLATFORM:
             if (hibernation_ops)
                 break;
             /* not a valid mode, continue with loop */
             continue;
         }
         if (i == hibernation_mode)
             buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
         else
             buf += sprintf(buf, "%s ", hibernation_modes[i]);
     }
     buf += sprintf(buf, "\n");
     return buf-start;
 }
 
 static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
               const char *buf, size_t n)
 {
     int error = 0;
     int i;
     int len;
     char *p;
     int mode = HIBERNATION_INVALID;
 
     if (!hibernation_available())
         return -EPERM;
 
     p = memchr(buf, '\n', n);
     len = p ? p - buf : n;
 
     lock_system_sleep();
     for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
         if (len == strlen(hibernation_modes[i])
             && !strncmp(buf, hibernation_modes[i], len)) {
             mode = i;
             break;
         }
     }
     if (mode != HIBERNATION_INVALID) {
         switch (mode) {
         case HIBERNATION_SHUTDOWN:
         case HIBERNATION_REBOOT:
 #ifdef CONFIG_SUSPEND
         case HIBERNATION_SUSPEND:
 #endif
         case HIBERNATION_TEST_RESUME:
             hibernation_mode = mode;
             break;
         case HIBERNATION_PLATFORM:
             if (hibernation_ops)
                 hibernation_mode = mode;
             else
                 error = -EINVAL;
         }
     } else
         error = -EINVAL;
 
     if (!error)
         pm_pr_dbg("Hibernation mode set to '%s'\n",
                    hibernation_modes[mode]);
     unlock_system_sleep();
     return error ? error : n;
 }
 
 power_attr(disk);
 
 static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
                char *buf)
 {
     return sprintf(buf, "%d:%d\n", MAJOR(swsusp_resume_device),
                MINOR(swsusp_resume_device));
 }
 
 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
                 const char *buf, size_t n)
 {
     dev_t res;
     int len = n;
     char *name;
 
     if (len && buf[len-1] == '\n')
         len--;
     name = kstrndup(buf, len, GFP_KERNEL);
     if (!name)
         return -ENOMEM;
 
     res = name_to_dev_t(name);
     kfree(name);
     if (!res)
         return -EINVAL;
 
     lock_system_sleep();
     swsusp_resume_device = res;
     unlock_system_sleep();
     pm_pr_dbg("Configured hibernation resume from disk to %u\n",
           swsusp_resume_device);
     noresume = 0;
     software_resume();
     return n;
 }
 
 power_attr(resume);
 
 static ssize_t resume_offset_show(struct kobject *kobj,
                   struct kobj_attribute *attr, char *buf)
 {
     return sprintf(buf, "%llu\n", (unsigned long long)swsusp_resume_block);
 }
 
 static ssize_t resume_offset_store(struct kobject *kobj,
                    struct kobj_attribute *attr, const char *buf,
                    size_t n)
 {
     unsigned long long offset;
     int rc;
 
     rc = kstrtoull(buf, 0, &offset);
     if (rc)
         return rc;
     swsusp_resume_block = offset;
 
     return n;
 }
 
 power_attr(resume_offset);
 
 static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
                    char *buf)
 {
     return sprintf(buf, "%lu\n", image_size);
 }
 
 static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
                 const char *buf, size_t n)
 {
     unsigned long size;
 
     if (sscanf(buf, "%lu", &size) == 1) {
         image_size = size;
         return n;
     }
 
     return -EINVAL;
 }
 
 power_attr(image_size);
 
 static ssize_t reserved_size_show(struct kobject *kobj,
                   struct kobj_attribute *attr, char *buf)
 {
     return sprintf(buf, "%lu\n", reserved_size);
 }
 
 static ssize_t reserved_size_store(struct kobject *kobj,
                    struct kobj_attribute *attr,
                    const char *buf, size_t n)
 {
     unsigned long size;
 
     if (sscanf(buf, "%lu", &size) == 1) {
         reserved_size = size;
         return n;
     }
 
     return -EINVAL;
 }
 
 power_attr(reserved_size);
 
 static struct attribute *g[] = {
     &disk_attr.attr,
     &resume_offset_attr.attr,
     &resume_attr.attr,
     &image_size_attr.attr,
     &reserved_size_attr.attr,
     NULL,
 };
 
 
 static const struct attribute_group attr_group = {
     .attrs = g,
 };
 
 
 static int __init pm_disk_init(void)
 {
     return sysfs_create_group(power_kobj, &attr_group);
 }
 
 core_initcall(pm_disk_init);
 
 
 static int __init resume_setup(char *str)
 {
     if (noresume)
         return 1;
 
     strncpy(resume_file, str, 255);
     return 1;
 }
 
 static int __init resume_offset_setup(char *str)
 {
     unsigned long long offset;
 
     if (noresume)
         return 1;
 
     if (sscanf(str, "%llu", &offset) == 1)
         swsusp_resume_block = offset;
 
     return 1;
 }
 
 static int __init hibernate_setup(char *str)
 {
     if (!strncmp(str, "noresume", 8)) {
         noresume = 1;
     } else if (!strncmp(str, "nocompress", 10)) {
         nocompress = 1;
     } else if (!strncmp(str, "no", 2)) {
         noresume = 1;
         nohibernate = 1;
     } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
            && !strncmp(str, "protect_image", 13)) {
         enable_restore_image_protection();
     }
     return 1;
 }
 
 static int __init noresume_setup(char *str)
 {
     noresume = 1;
     return 1;
 }
 
 static int __init resumewait_setup(char *str)
 {
     resume_wait = 1;
     return 1;
 }
 
 static int __init resumedelay_setup(char *str)
 {
     int rc = kstrtouint(str, 0, &resume_delay);
 
     if (rc)
         pr_warn("resumedelay: bad option string '%s'\n", str);
     return 1;
 }
 
 static int __init nohibernate_setup(char *str)
 {
     noresume = 1;
     nohibernate = 1;
     return 1;
 }
 
 __setup("noresume", noresume_setup);
 __setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
 __setup("hibernate=", hibernate_setup);
 __setup("resumewait", resumewait_setup);
 __setup("resumedelay=", resumedelay_setup);
 __setup("nohibernate", nohibernate_setup);

This page was automatically generated by the 2.1.0 LXR engine. The LXR team