From: Samuel Wu Date: Wed, 19 Nov 2025 17:14:24 +0000 (-0800) Subject: PM: sleep: Add support for wakeup during filesystem sync X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bf8867eae17fde94d7081545cf90ca8d5aba690a;p=thirdparty%2Flinux.git PM: sleep: Add support for wakeup during filesystem sync Add helper function pm_sleep_fs_sync() and related data structures as a preparation for allowing system suspend and hibernation to be aborted by wakeup events while syncing file systems. The new function, to be called by the suspend process in order to sync file systems, uses a dedicated ordered workqueue to run ksys_sync_helper() in parallel with the calling process. Next, it waits for the completion of the filesystem sync and periodically checks if any system wakeup events are pending, in which case it will return an error. If that happens while the filesystem sync is still in progress, it will continue, possibly after pm_sleep_fs_sync() has returned, and if that function is called again before the sync is complete, a new work item to run ksys_sync_helper() again will be queued (and waited for) to increase the likelihood of writing all of the dirty pages in memory back to persistent storage. Suggested-by: Saravana Kannan Signed-off-by: Samuel Wu Co-developed-by: Rafael J. Wysocki [ rjw: Subject and changelog rewrite, tags adjustment ] Link: https://patch.msgid.link/20251119171426.4086783-2-wusamuel@google.com Signed-off-by: Rafael J. Wysocki --- diff --git a/kernel/power/main.c b/kernel/power/main.c index 549f51ca3a1e6..e76a55583ec6f 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -18,6 +18,8 @@ #include #include #include +#include +#include #include "power.h" @@ -92,6 +94,61 @@ void ksys_sync_helper(void) } EXPORT_SYMBOL_GPL(ksys_sync_helper); +#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION) +/* Wakeup events handling resolution while syncing file systems in jiffies */ +#define PM_FS_SYNC_WAKEUP_RESOLUTION 5 + +static atomic_t pm_fs_sync_count = ATOMIC_INIT(0); +static struct workqueue_struct *pm_fs_sync_wq; +static DECLARE_WAIT_QUEUE_HEAD(pm_fs_sync_wait); + +static bool pm_fs_sync_completed(void) +{ + return atomic_read(&pm_fs_sync_count) == 0; +} + +static void pm_fs_sync_work_fn(struct work_struct *work) +{ + ksys_sync_helper(); + + if (atomic_dec_and_test(&pm_fs_sync_count)) + wake_up(&pm_fs_sync_wait); +} +static DECLARE_WORK(pm_fs_sync_work, pm_fs_sync_work_fn); + +/** + * pm_sleep_fs_sync() - Sync file systems in an interruptible way + * + * Return: 0 on successful file system sync, or -EBUSY if the file system sync + * was aborted. + */ +int pm_sleep_fs_sync(void) +{ + pm_wakeup_clear(0); + + /* + * Take back-to-back sleeps into account by queuing a subsequent fs sync + * only if the previous fs sync is running or is not queued. Multiple fs + * syncs increase the likelihood of saving the latest files immediately + * before sleep. + */ + if (!work_pending(&pm_fs_sync_work)) { + atomic_inc(&pm_fs_sync_count); + queue_work(pm_fs_sync_wq, &pm_fs_sync_work); + } + + while (!pm_fs_sync_completed()) { + if (pm_wakeup_pending()) + return -EBUSY; + + wait_event_timeout(pm_fs_sync_wait, pm_fs_sync_completed(), + PM_FS_SYNC_WAKEUP_RESOLUTION); + } + + return 0; +} +#endif /* CONFIG_SUSPEND || CONFIG_HIBERNATION */ + /* Routines for PM-transition notifications */ static BLOCKING_NOTIFIER_HEAD(pm_chain_head); @@ -231,10 +288,10 @@ static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr power_attr(mem_sleep); /* - * sync_on_suspend: invoke ksys_sync_helper() before suspend. + * sync_on_suspend: Sync file systems before suspend. * - * show() returns whether ksys_sync_helper() is invoked before suspend. - * store() accepts 0 or 1. 0 disables ksys_sync_helper() and 1 enables it. + * show() returns whether file systems sync before suspend is enabled. + * store() accepts 0 or 1. 0 disables file systems sync and 1 enables it. */ bool sync_on_suspend_enabled = !IS_ENABLED(CONFIG_SUSPEND_SKIP_SYNC); @@ -1066,16 +1123,26 @@ static const struct attribute_group *attr_groups[] = { struct workqueue_struct *pm_wq; EXPORT_SYMBOL_GPL(pm_wq); -static int __init pm_start_workqueue(void) +static int __init pm_start_workqueues(void) { pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0); + if (!pm_wq) + return -ENOMEM; - return pm_wq ? 0 : -ENOMEM; +#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION) + pm_fs_sync_wq = alloc_ordered_workqueue("pm_fs_sync", 0); + if (!pm_fs_sync_wq) { + destroy_workqueue(pm_wq); + return -ENOMEM; + } +#endif + + return 0; } static int __init pm_init(void) { - int error = pm_start_workqueue(); + int error = pm_start_workqueues(); if (error) return error; hibernate_image_size_init(); diff --git a/kernel/power/power.h b/kernel/power/power.h index 7ccd709af93f5..75b63843886ee 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -19,6 +19,7 @@ struct swsusp_info { } __aligned(PAGE_SIZE); #if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION) +extern int pm_sleep_fs_sync(void); extern bool filesystem_freeze_enabled; #endif