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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /kernel/freezer.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--kernel/freezer.c235
1 files changed, 235 insertions, 0 deletions
diff --git a/kernel/freezer.c b/kernel/freezer.c
new file mode 100644
index 0000000000..4fad0e6fca
--- /dev/null
+++ b/kernel/freezer.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kernel/freezer.c - Function to freeze a process
+ *
+ * Originally from kernel/power/process.c
+ */
+
+#include <linux/interrupt.h>
+#include <linux/suspend.h>
+#include <linux/export.h>
+#include <linux/syscalls.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+
+/* total number of freezing conditions in effect */
+DEFINE_STATIC_KEY_FALSE(freezer_active);
+EXPORT_SYMBOL(freezer_active);
+
+/*
+ * 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 freezer_active 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);
+
+bool frozen(struct task_struct *p)
+{
+ return READ_ONCE(p->__state) & TASK_FROZEN;
+}
+
+/* Refrigerator is place where frozen processes are stored :-). */
+bool __refrigerator(bool check_kthr_stop)
+{
+ unsigned int state = get_current_state();
+ bool was_frozen = false;
+
+ pr_debug("%s entered refrigerator\n", current->comm);
+
+ WARN_ON_ONCE(state && !(state & TASK_NORMAL));
+
+ for (;;) {
+ bool freeze;
+
+ set_current_state(TASK_FROZEN);
+
+ spin_lock_irq(&freezer_lock);
+ freeze = freezing(current) && !(check_kthr_stop && kthread_should_stop());
+ spin_unlock_irq(&freezer_lock);
+
+ if (!freeze)
+ break;
+
+ was_frozen = true;
+ schedule();
+ }
+ __set_current_state(TASK_RUNNING);
+
+ pr_debug("%s left refrigerator\n", current->comm);
+
+ 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);
+ }
+}
+
+static int __set_task_frozen(struct task_struct *p, void *arg)
+{
+ unsigned int state = READ_ONCE(p->__state);
+
+ if (p->on_rq)
+ return 0;
+
+ if (p != current && task_curr(p))
+ return 0;
+
+ if (!(state & (TASK_FREEZABLE | __TASK_STOPPED | __TASK_TRACED)))
+ return 0;
+
+ /*
+ * Only TASK_NORMAL can be augmented with TASK_FREEZABLE, since they
+ * can suffer spurious wakeups.
+ */
+ if (state & TASK_FREEZABLE)
+ WARN_ON_ONCE(!(state & TASK_NORMAL));
+
+#ifdef CONFIG_LOCKDEP
+ /*
+ * It's dangerous to freeze with locks held; there be dragons there.
+ */
+ if (!(state & __TASK_FREEZABLE_UNSAFE))
+ WARN_ON_ONCE(debug_locks && p->lockdep_depth);
+#endif
+
+ WRITE_ONCE(p->__state, TASK_FROZEN);
+ return TASK_FROZEN;
+}
+
+static bool __freeze_task(struct task_struct *p)
+{
+ /* TASK_FREEZABLE|TASK_STOPPED|TASK_TRACED -> TASK_FROZEN */
+ return task_call_func(p, __set_task_frozen, NULL);
+}
+
+/**
+ * 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;
+
+ spin_lock_irqsave(&freezer_lock, flags);
+ if (!freezing(p) || frozen(p) || __freeze_task(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_NORMAL);
+
+ spin_unlock_irqrestore(&freezer_lock, flags);
+ return true;
+}
+
+/*
+ * The special task states (TASK_STOPPED, TASK_TRACED) keep their canonical
+ * state in p->jobctl. If either of them got a wakeup that was missed because
+ * TASK_FROZEN, then their canonical state reflects that and the below will
+ * refuse to restore the special state and instead issue the wakeup.
+ */
+static int __set_task_special(struct task_struct *p, void *arg)
+{
+ unsigned int state = 0;
+
+ if (p->jobctl & JOBCTL_TRACED)
+ state = TASK_TRACED;
+
+ else if (p->jobctl & JOBCTL_STOPPED)
+ state = TASK_STOPPED;
+
+ if (state)
+ WRITE_ONCE(p->__state, state);
+
+ return state;
+}
+
+void __thaw_task(struct task_struct *p)
+{
+ unsigned long flags, flags2;
+
+ spin_lock_irqsave(&freezer_lock, flags);
+ if (WARN_ON_ONCE(freezing(p)))
+ goto unlock;
+
+ if (lock_task_sighand(p, &flags2)) {
+ /* TASK_FROZEN -> TASK_{STOPPED,TRACED} */
+ bool ret = task_call_func(p, __set_task_special, NULL);
+ unlock_task_sighand(p, &flags2);
+ if (ret)
+ goto unlock;
+ }
+
+ wake_up_state(p, TASK_FROZEN);
+unlock:
+ 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);