From 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 12:05:51 +0200 Subject: Adding upstream version 5.10.209. Signed-off-by: Daniel Baumann --- kernel/freezer.c | 176 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 176 insertions(+) create mode 100644 kernel/freezer.c (limited to 'kernel/freezer.c') diff --git a/kernel/freezer.c b/kernel/freezer.c new file mode 100644 index 000000000..dc520f01f --- /dev/null +++ b/kernel/freezer.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kernel/freezer.c - Function to freeze a process + * + * Originally from kernel/power/process.c + */ + +#include +#include +#include +#include +#include +#include + +/* total number of freezing conditions in effect */ +atomic_t system_freezing_cnt = ATOMIC_INIT(0); +EXPORT_SYMBOL(system_freezing_cnt); + +/* indicate whether PM freezing is in effect, protected by + * system_transition_mutex + */ +bool pm_freezing; +bool pm_nosig_freezing; + +/* protects freezing and frozen transitions */ +static DEFINE_SPINLOCK(freezer_lock); + +/** + * freezing_slow_path - slow path for testing whether a task needs to be frozen + * @p: task to be tested + * + * This function is called by freezing() if system_freezing_cnt isn't zero + * and tests whether @p needs to enter and stay in frozen state. Can be + * called under any context. The freezers are responsible for ensuring the + * target tasks see the updated state. + */ +bool freezing_slow_path(struct task_struct *p) +{ + if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK)) + return false; + + if (test_tsk_thread_flag(p, TIF_MEMDIE)) + return false; + + if (pm_nosig_freezing || cgroup_freezing(p)) + return true; + + if (pm_freezing && !(p->flags & PF_KTHREAD)) + return true; + + return false; +} +EXPORT_SYMBOL(freezing_slow_path); + +/* Refrigerator is place where frozen processes are stored :-). */ +bool __refrigerator(bool check_kthr_stop) +{ + /* Hmm, should we be allowed to suspend when there are realtime + processes around? */ + bool was_frozen = false; + long save = current->state; + + pr_debug("%s entered refrigerator\n", current->comm); + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + + spin_lock_irq(&freezer_lock); + current->flags |= PF_FROZEN; + if (!freezing(current) || + (check_kthr_stop && kthread_should_stop())) + current->flags &= ~PF_FROZEN; + spin_unlock_irq(&freezer_lock); + + if (!(current->flags & PF_FROZEN)) + break; + was_frozen = true; + schedule(); + } + + pr_debug("%s left refrigerator\n", current->comm); + + /* + * Restore saved task state before returning. The mb'd version + * needs to be used; otherwise, it might silently break + * synchronization which depends on ordered task state change. + */ + set_current_state(save); + + return was_frozen; +} +EXPORT_SYMBOL(__refrigerator); + +static void fake_signal_wake_up(struct task_struct *p) +{ + unsigned long flags; + + if (lock_task_sighand(p, &flags)) { + signal_wake_up(p, 0); + unlock_task_sighand(p, &flags); + } +} + +/** + * freeze_task - send a freeze request to given task + * @p: task to send the request to + * + * If @p is freezing, the freeze request is sent either by sending a fake + * signal (if it's not a kernel thread) or waking it up (if it's a kernel + * thread). + * + * RETURNS: + * %false, if @p is not freezing or already frozen; %true, otherwise + */ +bool freeze_task(struct task_struct *p) +{ + unsigned long flags; + + /* + * This check can race with freezer_do_not_count, but worst case that + * will result in an extra wakeup being sent to the task. It does not + * race with freezer_count(), the barriers in freezer_count() and + * freezer_should_skip() ensure that either freezer_count() sees + * freezing == true in try_to_freeze() and freezes, or + * freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task + * normally. + */ + if (freezer_should_skip(p)) + return false; + + spin_lock_irqsave(&freezer_lock, flags); + if (!freezing(p) || frozen(p)) { + spin_unlock_irqrestore(&freezer_lock, flags); + return false; + } + + if (!(p->flags & PF_KTHREAD)) + fake_signal_wake_up(p); + else + wake_up_state(p, TASK_INTERRUPTIBLE); + + spin_unlock_irqrestore(&freezer_lock, flags); + return true; +} + +void __thaw_task(struct task_struct *p) +{ + unsigned long flags; + + spin_lock_irqsave(&freezer_lock, flags); + if (frozen(p)) + wake_up_process(p); + spin_unlock_irqrestore(&freezer_lock, flags); +} + +/** + * set_freezable - make %current freezable + * + * Mark %current freezable and enter refrigerator if necessary. + */ +bool set_freezable(void) +{ + might_sleep(); + + /* + * Modify flags while holding freezer_lock. This ensures the + * freezer notices that we aren't frozen yet or the freezing + * condition is visible to try_to_freeze() below. + */ + spin_lock_irq(&freezer_lock); + current->flags &= ~PF_NOFREEZE; + spin_unlock_irq(&freezer_lock); + + return try_to_freeze(); +} +EXPORT_SYMBOL(set_freezable); -- cgit v1.2.3